PRE-FEASIBILITY REPORT FOR DRILLING TWO EXPLORATORY WELLS CHAR & CHAQ

Transcription

1 PRE-FEASIBILITY REPORT FOR DRILLING TWO EXPLORATORY WELLS CHAR & CHAQ IN CHARALI MINING LEASE SIVASAGAR DISTRICT, ASSAM NORTH ASSAM SHELF A&AA BASIN ONGC, JORHAT 1

2 Pre-feasibility Report of Drilling of Two Exploratory Wells in CHARALI ML, Sivasagar District, Assam 1. Introduction Charali Mining Lease (ML) is one of the important oil producing fields of ONGC situated in Sivasagar District of Assam. The area of this lease is square kilometers. This ML area forms the part of rth Assam shelf and had been producing hydrocarbons for more than three decades from Barails and Tipams. A 20 years ML was obtained with effect from (Ref: MOPNG, Govt. of India, Letter. O-12012/94/2002-ONG/D-IV, dated 29 th April-2002) and is valid upto So far, 46 numbers of wells (including exploratory wells and development wells) have been drilled in this field with depths ranging from 2400m to as deep as 4000m. Geological Setting of the ML; The general geology of the area is well known from subsurface and outcrop data. The stratigraphic column consists of Archean metamorphic Basement overlain by Jaintia Group of Paleocene to Eocene age consisting of Tura, Sylhet and Kopili formations. The Jaintia Group is overlain by the Barail Group of sediments consisting of Disangmukh, Demulgaon and Rudrasagar formations of Eocene to Oligocene age and underlain by Tipam Group of Miocene to Pliocene age consisting of Geleki sandstone, Lakwa Sandstone, Girujan clay and Nazira Sandstone. Moran Group of younger sediments of Plio-Pleistocene to Recent age, comprising of Namsang, Dhekiajuli formations and Alluvium overlies the Tipam Group. The Charali structure can be described as an anticlinal fault closure developed on a predominantly NNE-SSW trending fault, termed the Charali Western Bounding Fault that extends from the north of Changmaigaon field and northward upto the Rudrasagar Field. Reservoirs in different stratigraphic levels starting from various sand units of Barail Group (BMS, BCS-I, BCS-V, BCS-VA) to sands within Tipam Group (TS-5, TS-4, TS-2 & TS-1) have been charged in different part of the ML depending on favorable entrapment conditions. Shales/Claystones of within these formations and clays in Girujan & Namsang have acted as cap rock facies. Based on evaluation of G & G data of the ML the following locations have been identified for drilling exploratory wells. 1.) CHAR and 2.) CHAQ 1.2 Technical Justification for Released Locations for Exploratory Drilling 1.) CHAR: The location CHAR is mapped as a fault closure at LCM and Tipam (TS-5) and BMS levels. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4, TS-5 & BMS pays) & Barail Group. The location is to be drilled to a depth of 3550 m (Measured depth) and is techno-economically viable. The details of the location are given below. 2

3 Sl Prospect Proposed PEL-ML Category TD (m) Loc. Reference Objective Well MD Latitude / Longitude Location 1 CHARALI CHAR CHARALI -ML Expl. B-cat Lat: N Long: E TS-4,TS-5 & BMS Pays Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel 2.) CHAQ: The location CHAQ is mapped as a fault closure at LCM and Tipam (TS-5) levels. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4 & TS-5 pays) & Barail Group. The location is to be drilled to a depth of 3150 m (Measured depth) and is techno-economically viable. The details of the location are given below. Sl Prospect Proposed PEL-ML Category TD (m) Loc. Reference Objective Well MD Latitude / Longitude Location 2 CHARALI CHAQ CHARALI -ML Expl. B-cat Lat: N Long: E TS-4 & TS-5 Pays Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel The locations CHAR and CHAQ have been firmed up to oil exploration and are likely to accrete inplace hydrocarbons to the tune of about 2.53 MMT. This will result in increase of hydrocarbon production and further improvement of the country s economy. The locations are techno-economically viable. 2.0 Details of proposed Drilling Activity ONGC owned electrical type E-2000 series Rigs (BHEL Rig), which has a capacity to drill to the depth of 6000m is likely to be deployed for undertaking drilling in the block. The technical details of the proposed drilling activities are given below: 3

4 Well location / Depth CHAR (TargetDepth:3550 meter MD) of wells to be drilled One One Duration of drilling 6-7 months 6-7 months Qty of drilling fluid cu.m 900 m m 3 Qty. of cuttings, cu.m Appox m 3 Appox m 3 CHAQ (Target Depth: 3150meter MD) Qty. of drlg. Waste water, cu.m Location details 1400 m m 3 Latitude: N Longitude: E Latitude: N Longitude: E Distance of block boundary coastline Development plan in case of strike Onland location To be chalked out after hydrocarbon strike Onland location To be chalked out after hydrocarbon strike HC reserve (initially in place) 1.41 MMT 1.12 MMT Formation pressure Hydrostatic Hydrostatic Test flaring, duration 2 to 3 days, Flare details: Confined to the oil pit. 2 to 3 days, Flare details: Confined to the o 4

5 2.1 Details of the drilling rig proposed to be deployed Type of rig Drilling mud composition Power generator type and no s Diesel consumption Qty. of fresh water requirement & source Manpower on rig Material requirement & Mobilization Details of solids handling system Details of sewage treatment facility, if any Waste pit availability & size 30m X 20m X 1.5m 30m X 20m X 1.5m 40m X 30m X 1.5m Oil pit availability & size Electrical rig Water based drilling fluid AC-SCR type. Four numbers. 200 litres/hour 2000m3. Transported from nearby source Through contractor. 30 person / 12 hrs shift From ONGC base, Sivsagar Shale shakers GPM capacity Desander GPM capacity Desilter-1200 GPM capacity t applicable 25m x 10m x 1m 2.2 Drilling Operations Only water based drilling mud will be used. The quantity of drill cuttings generated will be around m3. The quantity of wastewater produced will be about 15 m3/day. The rig will be provided with solids handling system comprising Shale shakers (1200 GPM), desander (1200 GPM) and de-silter (1200 GPM) and Degasser with vacuum pump. Drilling operations will be carried out using an electrical type drilling unit (Drilling Rig) for drilling of oil and gas wells. It consists of a derrick, at the top of which there is a crown block and a hoisting block fitted with a hook. From the hook a swivel a Kelly stem is suspended passing through a square or hexagonal Kelly bush which fits into the rotary table. The rotary table receives the power from an electric motor. The electric motor rotates the rotary table which passes through the Kelly bush and the rotations are transmitted to the bit as the drilling progresses, the drill pipe in singles are added to continue the drilling process. At the end of the bit life, the drill pipes are pulled out in stands and stacked on the derrick platform. A stand normally has 3 single drill pipes. After changing the bit, the drill string is run back into the hole and further drilling is continued. This process continues till the target depth is reached. During the course of drilling, cuttings are generated due to crushing action of the bit. These cuttings are removed by flushing the well with duplex/triplex mud pumps. The mud from the pump discharge through the rotary hose connected to stationary part of the swivel, the drill string and bit nozzles. The mud coming out of the bit nozzles pushes the cuttings up hole and transports them to the surface through the annular space between the drill string and the hole. The mud not only carries away crushed rock from the bottom of the hole but it also cools the bit as it gets heated due to friction with formation while rotating. The mud also helps in balancing subsurface formation pressures and by forming a cake on the walls of the well diminishes the possibility of crumbling or caving of the well bore. At the surface, the mud coming out from well along with the cuttings falls in a trough, passes through the solids control equipments i.e. shale shaker, de-sander and de-silter. These 5

6 equipments remove the solids of different sizes which get mixed with the mud during the course of drilling. The cleaned mud flows back to the suction tanks to be again pumped into the well. The drilling mud/fluid circulation is thus a continuous cyclic operation. The most suitable clay for mud preparation is bentonite which is capable of forming highly dispersed colloidal solutions. Various other chemicals are also used in mud preparation as per requirements dictated by the temperature/pressure conditions of the wells. The mud is continuously tested for its density, viscosity, yield point, water loss, ph value etc. to ensure that the drilling operations can be sustained without any down hole complications. 2.3 Drilling Facilities Drilling is a temporary activity which will continue for about 6-7 months for each well in the block. The rigs are self-contained for all routine jobs. Once the drilling operations are completed, and if sufficient indications of hydrocarbons are noticed while drilling, the well is tested by perforation in the production casing. This normally takes 2-3 days. If the well is found to be successful hydrocarbon bearing, it is sealed off for future development. If no commercial hydrocarbon is struck, the well is abandoned according to existing safety norms. 2.4 General Requirements of Drilling Exploratory drilling programme requires the following common facilities: a. Drilling muds Drilling of wells requires specially formulated muds which basically comprise inert earth materials like bentonite, barite in water with several additives to give mud weight, fluidity and filter cake characteristics while drilling. The drilling muds have several functions like lubrication and cooling of the drill bit, balancing subsurface formation, bringing out the drill cuttings from the well bore, thixotropic property to hold cuttings during non-operations, formation of thin cake to prevent liquid loss along well bore etc. Several additives are mixed into the mud system to give the required properties. Water based mud will be used to the possible extent in exploratory drilling but use of synthetic based mud may require due to complexities associated with the geological formations and associated hole stability problems. The constituents of water based mud (WBM) are given in Table 1.2. The special additives and their functions in WBM are shown in Table 1.3. b. Power Generation The drilling process requires rotation of drill bit through the draw works which require power. The power requirement of the drilling rig will be met by using the four diesel generator sets with a diesel consumption of about 4.8 Kl / day. The exhaust stacks of the DG sets are likely to vent the emissions. c. Water requirements The water requirement in a drilling rig is mainly meant for preparation of drilling mud apart from washings and domestic use. While the former consumes the majority of water requirement, the water requirement for domestic and wash use is very less. The daily water 6

7 consumption will be 25 m3/d of which 15m3/d will be used for mud preparation and 10m3/d will be used for domestic purposes including drinking. d. Domestic wastewater The operating personnel in the drilling rigs will operate mostly from nearby ONGC colonies. However suitable soak pits will be available at the drilling site. e. Solids removal The rock cuttings and fragments of shale, sand and silt associated with the return drilling fluid during well drilling will be separated using shale shakers and other solids removal equipment like de-sanders and de-silters. The recovered mud will be reused while the rejected solids will be collected and discharged into the waste pit. f. Drill cuttings and waste residual muds During drilling operations, approx m3 per well of wet drill cuttings are expected to be generated from each well depending on the type of formation and depth of drilling. In addition to the cuttings m3/day of wastewater is likely to be generated during well drilling. The waste residual muds and drill cuttings which contain clay, sand etc. will be disposed into the waste pit. g. Testing Testing facilities will be available at drilling rig for separation of liquid phase and burning of all hydrocarbons during testing. The test flare boom will be located at a distance from the drilling rig. h. Chemical storage The drilling rig will have normal storage facilities for fuel oil, required chemicals and the necessary tubulars and equipment. The storage places will be clearly marked with safe operating facilities and practices. i. Manpower The drilling rig will be operated by approx. 30 persons on the rig at anytime. The manpower will operate in two shifts with continuous operations on the rig. j. Logistics Crew transfers to and from the drilling rig, materials, diesel and chemicals will be through light vehicles, trucks and trailers. 3.0 Investment anticipated The anticipated cost of drilling of wells (which includes the PEL fees, EIA study, stacking of the location, land acquisition, site preparation and drilling activity has been tabulated below. 7

8 S. Name of the locations Investment anticipated 1 CHAR Rs. 40 crores 2 CHAQ Rs. 40 crores 3.1 Justification for Environmental Clearance Charali ML is highly prospective where oil and gas have been discovered and produced from a large stratigraphic column ranging from Barail Group to Girujan Formation. However there are areas within the ML which still have untapped hydrocarbons. These locations are proposed for these exploiting these pools. In view of the above it is proposed to grant the environmental clearance at the earliest so that the drilling commitments as well post drilling evaluations could be carried out. The total area proposed for environmental clearance amounting to Sq Km is shown in the map enclosed at Fig 1.1 SL. NO. 1 The coordinates of the area proposed for environmental clearance are as follows: ML NAME (AREA ) CHARALI ML (Area: Sq. Km.) BOUNDARY LATITUDE LONGITUDE POINTS DEG. MIN. SEC. DEG. MIN. SEC. A B C D E F G Table 1.2: Ingredients of water based drilling fluid Sl. Chemicals 1. Barite 2. Bentonite 3. Carboxyl Methyl Cellulose 4. Mud thinner / Conditioner 5. Resinated Lignite 6. n weighted spotting fluid 8

9 7. Weighted spotting fluid 8. EP lube 9. Drilling detergent 10. Caustic soda 11. Potassium Chloride 12. Soda ash Table 1.3: Special Additives and Their Functions in Water Based Drilling Fluids Sl. Discharge Category Exploration 1. Sodium Bicarbonate Eliminates excess calcium ions due to cement contamination 2. Sodium chloride Minimize borehole washout in salt zone 3. Groundnut shells, mica of Minimize the loss of drilling mud to formation cellophane 4. Cellulose polymers or starch Counter thick, sticky filter cake, control filtration loss to formation 5. Aluminum stearate Minimize foaming. 6. Vegetable oil lubricant Reduce torque and drag on drill string. 7. Pill of oil based mud spotting fluid Counter differential pressure sticking of string. placed down hole opposite contact zone to free pipe. 9

10 APPENDIX-I (See paragraph 6) FORM 1 I Basic Information: Serial. Item Detail 1. Name of the project/s Drilling of two exploratory wells in Charali ML area, Sivasagar District, Assam. 2. S. in the Schedule MOPNG, Govt of India, Award of ML Letter. O-12012/94/2002- ONG/D-IV, dated 29 th April Proposed Capacity/ area/length/ tonnage to be handled/ command area/ lease area/ number of wells to be drilled Sl. no. Name of location Target Depth (meters) District 1. CHAQ 3150m Sivasagar 2. CHAR 3550m Sivasagar 4. New/Expansion/ Modernization New 5. Existing capacity/area etc. yet to be acquired 6. Category of Project i.e. A or B A 10

11 7. Does it attract the general condition? If yes, please specify. 8. Does it attract the specific condition? If yes, please specify. 9. Location 1.) CHAQ Plot/Survey/Khasra Village/Area Surface Co-ordinates: Latitude: N Longitude: E Mothiasiga, Mouza - Juktoli, Sivasagar. Tehsil Revenue Circle:- Nazira District Sivasagar State Assam Nearest railway station/airport along with distance in kms. Nearest Town, city, District Headquarters along with distance in kms. Village Panchayats, Zilla Parishad, Municipal Corporation, Local body (Complete postal addresses with telephone nos. to be given Location Sivasagar Town railway station in Assam approximately 5.5 km, Jorhat Airport (Assam) is at a distance of approximately 65km. Sivasagar Town, District: Sivasagar, Assam, Approximately 5.5km. Village Panchayat Juktoli, ZP Juktoli, P.O.-Rajmao PIN Ph. : ) CHAR 11

12 Plot/Survey/Khasra Village/Area Surface Co-ordinates: Latitude: N Longitude: E Village Kurulakatia Mouza Meteka, Bongaon,Sivasagar, Assam Tehsil Revenue Circle Sivasagar District Sivasagar. State Assam Nearest railway station/airport along with distance in kms. Nearest Town, city, District Headquarters along with distance in kms. Village Panchayats, Zilla Parishad, Municipal Corporation, Local body (Complete postal addresses with telephone nos. to be given) Sivasagar Town railway station in Assam approximately 7 km, Jorhat Airport (Assam) is at a distance of approximately 65km. Sivasagar Town, District: Sivasagar, Assam, Approximately 7 km. Village Panchayat Rongpur, ZP Rongpur, P.O. Sivasagar, Pin Ph Name of the applicant ONGC LTD 11. Registered Address ONGC LTD, Jeevan Bharti, Tower-II, 124-Indira Chowk, New Delhi Address for correspondence Office of The Basin Manager, Luit Bhawan, ONGC, Cinnamara Complex, Cinnamara, Jorhat , Assam 12

13 Name C. Mahapatra Designation Basin Manager Address Luit Bhavan, ONGC, Cinnamara Complex, Cinnamara, Jorhat , Assam Pin Code Telephone Fax Details of Alternative Sites Examined, if any location of these sites should be shown on topo sheet. N/A 14. Interlinked Project 15. Whether separate application for interlinked project has been submitted? N/A 16. If yes, date of submission N/A 17. If no, reason N/A 18. Whether the proposal involves approval/ clearance under: if yes, details of same and their status to be given. (a) The Forest(Conservation) Act, 1980 (b) The Wildlife (Protection) Act,1972. The Forest clearance (Conservation) Act, 1980 will be taken as per norms. 13

14 (c) The C.R.Z tification 19. Whether there is any Government Order/Policy relevant/relating to the site 20. Forest land involved 21. Whether there is any litigation pending against the project and/or land in which the project is proposed to set up? (a) Name of the Court (b) Case (c) Orders/ directions of the Court, if any and its relevance with the project ne II Activity 1. Construction, operation or decommissioning of the Project involving actions, which will cause physical changes in the locality (topography, land use, changes in water bodies, etc.) Sl.. Information/Checklist confirmation / Details thereof (with approximate quantities / rates, wherever possible) with source of information data 1.1 Permanent or temporary change in Temporary Temporary change in land use land use, land cover or topography including increase in intensity of land use (with respect to local land use plan) 1.2 Clearance of existing land, vegetation Site leveling and fencing and buildings? 1.3 Creation of new land uses? n.a 1.4 Pre-construction investigations e.g. bore houses, soil testing? Hard field area. rmally soil testing not essential for shallow / temporary foundation for deployment of rig. 14

15 1.5 Construction works? Foundation for drilling rig deployment. Surface hardening and chemical shed. 1.6 Demolition works? n.a 1.7 Temporary sites used for construction works or housing of construction workers? 1.8 Above ground buildings, structures or earthworks including linear structures, cut and fill or excavations 1.9 Underground works including mining or tunneling? Temporary sheds will be constructed Temporary sheds of working staff during shift duties. Drilling will ranges from 3000 m up to 4000 m depth (Tentative) Reclamation works? Site will be restored after completion of well 1.11 Dredging? Onland project 1.12 Offshore structures? Onland project 1.13 Production and manufacturing processes? 1.14 Facilities for storage of goods or materials? 1.15 Facilities for treatment or disposal of solid waste or liquid effluents? 1.16 Facilities for long term housing of operational workers? n.a Mechanical and drilling spares and drilling chemicals in temporary sheds. Solid waste / drilled rock cuttings and liquid waste will be confined within the waste pit lined with impervious HDPE lining Rig workers are operating on daily or 14 days on/off pattern from their respective hometowns New road, rail or sea traffic during construction or operation? n.a 15

16 1.18 New road, rail, air waterborne or other transport infrastructure including new or altered routes and stations, ports, airports etc? 1.19 Closure or diversion of existing transport routes or infrastructure leading to changes in traffic movements? 1.20 New or diverted transmission lines or pipelines? Approach road envisaged be approx. 1 km from the existing public road network. n.a n.a 1.21 Impoundment, damming, culverting, realignment or other changes to the n.a hydrology of watercourses or aquifers? 1.22 Stream crossings? n.a Abstraction or transfers of water form ground or surface waters? Changes in water bodies or the land surface affecting drainage or run-off? Transport of personnel or materials for construction, operation or decommissioning? 1.26 Long-term dismantling or decommissioning or restoration works? 1.27 Ongoing activity during decommissioning which could have an impact on the environment? 1.28 Influx of people to an area in either temporarily or permanently? Surface water / Bore wells as per requirement. n.a Rig personnel to operate from the temporary drill site accommodation (bunk houses). n.a n.a n.a 16

17 1.29 Introduction of alien species? n.a 1.30 Loss of native species or genetic diversity? n.a 1.31 Any other actions? Nil n.a 2. Use of Natural resources for construction or operation of the Project (such as land, water, materials or energy, especially any resources which are non-renewable or in short supply): Sl.. Information / checklist confirmation / Details thereof (with approximate quantities /rates, wherever possible) with source of information data 2.1 Land especially undeveloped or agricultural land (ha) 2.2 Water (expected source & competing users) unit: KLD yes 100m x100m, agricultural land M3 / day for Drilling and domestic purpose 2.3 Minerals (MT) Nil n.a 2.4 Construction material stone, aggregates, and / soil (expected source MT) 2.5 Forests and timber (source MT) 2.6 Energy including electricity and fuels (source, competing users) Unit: fuel (MT), energy (MW) 2.7 Any other natural resources (use appropriate standard units) Sand / Stone / Cement 100 Tonnes from nearby dealers n.a 6 KL./day (Diesel for running captive Gensets) - Drilling rigs n.a 3. Use, storage, transport, handling or production of substances or materials, which could be harmful to human health or the environment or raise concerns about actual or perceived risks to human health. Sl.. Information/Checklist confirmation / Details thereof (with approximate quantities/rates, wherever possible) with source of information data 17

18 3.1 Use of substances or materials, which are hazardous (as per MSIHC rules) to human health or the environment (flora, fauna, and water supplies) Only water based mud will be used, which contains no hazardous raw material, however drilling will produce- 1. Drilling cuttings of m 3 2. Effluent/ waste water 900m 3 3. ETP/ only sludge ton 3.2 Changes in occurrence of disease or affect n.a disease vectors (e.g. insect or water borne diseases) 3.3 Affect the welfare of people e.g. by changing n.a living conditions? 3.4 Vulnerable groups of people who could be n.a affected by the project e.g. hospital patients, children, the elderly etc., 3.5 Any other causes Nil n.a 4. Production of solid wastes during construction or operation or decommissioning (MT/month) Sl.. Information/Checklist confirmation / Details thereof (with approximate quantities/rates, wherever possible) with source of information data 4.1 Spoil, overburden or mine wastes Drilled cuttings generated will be about m 3 during the drilling over a period of 4-5 months. 4.2 Municipal waste (domestic and or commercial wastes) 4.3 Hazardous wastes (as per Hazardous Waste Management Rules) 4.4 Other industrial process wastes Nil 4.5 Surplus product Nil Septic tank will be provided for toilets in the drill site (Sewage about 10 m3/day) 1. Spent oil (Sent to base for disposal) through SPCB approved agencies Spent oil generated will be around lts/month. 2. Drill cuttings are nontoxic & nonhazardous as per lab test reports. Drill cutting will be confined to waste pit (impervious HDPE lined). 18

19 4.6 Sewage sludge or other sludge from effluent treatment 4.7 Construction or demolition wastes Will be disposed of for in surface hardening within drill site area. 4.8 Redundant machinery or equipment Nil 4.9 Contaminated soils or other materials Nil Will be confined in impermeable waste pit within the drill site area Agricultural wastes Nil 4.11 Other solid wastes Nil 5. Release of pollutants or any hazardous, toxic or noxious substances to air (Kg/hr) Sl.. Information/Checklist confirmation / Details thereof (with approximate quantities/rates, wherever possible) with source of information data 5.1 Emissions from combustion of fossil fuels from stationary or mobile sources 5.2 Emissions from production processes 5.3 Emissions from materials handling including storage or transport 5.4 Emissions from construction activities including plant and equipment Nil Emissions from Captive Gensets (Rating: 6 x 750 KW) only 3 units will be normally operated for drilling rig. This is as per world over industrial practice. The emission of RSPM, SPM, SO 2, NO x, HC & HOC from G set and flare stack. Emission will be kept under control within the permissible limit as per CPCB guide line. Regular monitoring of ambient air will be carried out during operation. If the well is hydrocarbon bearing during production testing flaring of well fluids. This process will be for one/two days only. emission from storage and material handling equipment except emission from generator set. rmal emission from working JCB, trucks and trailers during the construction activities only. 19

20 5.5 Dust or odors from handling of materials including construction materials, sewage and waste 5.6 Emissions from incineration of waste Nil Nil 5.7 Emissions from burning of waste in Nil open air (e.g. slash materials, construction debris) 5.8 Emissions from any other sources Nil n.a 6. Generation of ise and Vibration, and Emissions of Light and Heat: Sl.. Information/Checklist confirmation From operation of equipment e.g. engines, ventilation plant, crushers / Details thereof (with approximate quantities/rates, wherever possible) with source of information data with source of information data ise levels within permissible limits (Personal Protective Equipment will be provided if required) 6.2 From industrial or similar Nil processes 6.3 From construction or demolition Nil 6.4 From blasting or piling Nil 6.5 From construction or operational Nil traffic 6.6 From lighting or cooling systems Nil 6.7 From any other sources Nil 7. Risks of contamination of land or water from releases of pollutants into the ground or into sewers, surface waters, groundwater, coastal waters or the sea: 20

21 Sl.. Information/Checklist confirmation / 7.1 From handling, storage, use or spillage of hazardous materials 7.2 From discharge of sewage or other effluents to water or the land (expected mode and place of discharge) 7.3 By deposition of pollutants emitted to air into the land or into water Details thereof (with approximate quantities/rates, wherever possible) with source of information data All effluents will be confined within impermeable waste pits Sewage waste is disposed of through Septic Tank. 7.4 From any other sources 7.5 Is there a risk of long term build up of pollutants in the environment from these sources? Exploratory drilling is a temporary activity lasting 4 to 5 months. 8. Risk of accidents during construction or operation of the Project, which could affect human health or the environment Sl.. Information/Checklist confirmation / Details thereof (with approximate quantities/rates, wherever possible) with source of information data 8.1 From explosions, spillages, fires etc from Nil storage, handling, use or production of hazardous substances 8.2 From any other causes Any potential risk will be handled as per existing contingency plan. ** 8.3 Could the project be affected by natural disasters causing environmental damage (e.g. floods, earthquakes, landslides, cloudburst etc)? ** Contingency plan enclosed 21

22 9. Factors which should be considered (such as consequential development) which could lead to environmental effects or the potential for cumulative impacts with other existing or planned activities in the locality S.. Information/Checklist confirmation / 9.1 Lead to development of supporting facilities, ancillary development or development stimulated by the project which could have impact on the environment e.g.: Supporting infrastructure (roads, power supply, waste or waste water treatment, etc.) housing development extractive industries supply industries other Details thereof (with approximate quantities/rates, wherever possible) with source of information data The exploratory drilling will lead to development / improvement of infrastructure (road, power supply). 9.2 Lead to after-use of the site, which could have an impact on the environment 9.3 Set a precedent for later developments Nil 9.4 Have cumulative effects due to proximity to other existing or planned projects with similar effects Nil industries is nearby III. Environmental Sensitivity: Sl Areas Name/ Identity Aerial distance (within 15 km.) Proposed project location boundary 1 Areas protected under international conventions, national or local legislation for their ecological, landscape, cultural or other related value. Historical Monuments around Sivasagar Town. Distance km. 22

23 2 Areas which are important or sensitive for ecological reasons wetlands, watercourses or other water bodies, coastal zone, biospheres, mountains, forests. 3 Areas used by protected, important or sensitive species of flora or fauna for breeding, nesting, foraging, resting, over wintering, migration. ne ne 4 Inland, coastal, marine or underground waters. ne 5 State, National boundaries. ne 6 Routes or facilities used by the public for access to recreation or other tourist, pilgrim areas. ne 7 Defence installations. ne 8 Densely populated or built-up area. Sivasagar Town. Distance km. 9 Areas occupied by sensitive man-made land uses (hospitals, schools, places of worship, community facilities). 10 Areas containing important, high quality or scarce resources (ground water resources, surface resources, forestry, agriculture, fisheries, tourism, minerals). 11 Areas already subjected to pollution or environmental damage. (those where existing legal environmental standards are exceeded). 12 Areas susceptible to natural hazard which could cause the project to present environmental problems (earthquakes, subsidence, landslides, erosion, flooding or extreme or adverse climatic conditions). Hospitals, schools etc. in Sivasagar Town ne N/A Nil Distance km. IV Proposed Terms of Reference for EIA studies 1. Project techno-economic feasibility report. 23

24 2. Justification for locations considered for exploratory drilling 3. Baseline studies for Air / water quality in the proposed exploratory drilling locations. 4. Site specific data collection for air / water quality within the vicinity of the drill site (5 km. radius) 5. Socio-economic impact of exploratory drilling activity. 6. Identification of environmental impacts and mitigation measures 7. Environment management plan for the proposed drilling. I hereby give undertaking that the data and information given in the application and enclosures are true to the best of my knowledge and belief and I am aware that if any part of the data and information submitted is found to be misleading at any stage the project will be rejected and clearance give, if any to the project will be revoked at our risk and cost Date: Place: Jorhat (Dr. A. K. Srivastava) GM (Geophysics) Block Manager-NAS 24

25 WELL IS OUT OF CONTROL- BLOW OUT DECLARED BLOW OUT RESTRICT THE ENTRY OF OUTSIDERS ORGANISE SEARCH AND RESCUE ORGANISE COUNT TALLIED? FIRST AID HEAD EVACUATE THE SITE BLOWOUT WITH FIRE EVACUATE SITE WAIT FOR INSTRUCTIONS GAS SPRAY WATER WAIT FOR FURTHER PRIMARY RESPONSE BLOWOUT WITHOUT FIRE OIL TAKE POLLUTION CONTROL WAIT FOR INSTRUCTIONS BASE RADIO INCIDENT REPORTING ASSET MANAGER / BASIN MANAGER HEAD DRILLING SERVICES SURFACE MANAGER & HEAD WELL SERVICES NEAREST POLICE STATION FOR MINOR INJURIES MOBILISE THE PATIENT TO NEAREST HOSPITAL EVACUATE SURROUNDINGS IF H2S PRESENTS M.R.O. OFFICE STATE FIRE DEPT. TASK FORCE ASSESSMENT OF SITUATION ON SITE SECONDARY RESPONSE R.C.M.T. S.E.M. ENGINEERING ON SITE MEETING CIVIL, ADMN., POLICE, STATE FIRE, MEDICAL SECURITY RELIEF WELL TEAM NOMINATE PROJECT CO-ORDINATOR BLOW OUT CONTROL & FIRE FIGHTING EQUIPMENT O.N.G.C. OUT SIDE FIELD INTERVENTION TEAM WORK OUT THE CONTROL STRATEGY POLLUTION CONTROL EQUIPMENT O.N.G.C. SUPPORT SERVICES MOBILIZE THE RESOURCES EXPERTS OUT SIDE O.N.G.C. LOGISTICS, COMMUNICATION, WORK SHOP, S.E.M., FIRE, MEDICAL, ESTABLISH INFRASTRUCTURE EXECUTE CONTROL PLAN -- COMMUNICATION -- FIRST AID -- ON SITE CAMP OUT SIDE 25

26 PRE-FEASIBILITY REPORT FOR DRILLING FOUR EXPLORATORY WELLS GKBS, GKBT, MKAD & NGAB IN GELEKI, SE GELEKI & MEKEYPORE-SANTAK-NAZIRA MINING LEASE AREAS SIVASAGAR DISTRICT, ASSAM NORTH ASSAM SHELF A&AA BASIN ONGC, JORHAT 1

27 Pre-feasibility Report for Drilling Four Exploratory Wells in Geleki, SE-Geleki & 1. Introduction Mekeypore-Santak-Nazira ML Areas Geleki and its satellite fields Mekeypore, Santak & Nazira are some of the important oil producing fields of ONGC situated in Sivasagar District of Assam. These areas form the part of rth Assam shelf and had been producing hydrocarbons for more than three decades from Barails and Tipams. ONGC has received Mining Lease of these areas from MOPNG, Govt of India for exploring and producing hydrocarbons. The Mining Lease (ML) areas with their respective validity are given below, Geological Setting of the MLs; 1. Geleki ML (Area: sq km, with effect from to ) 2. SE Geleki ML (Area:20.5 sq.km, with effect from to ) 3. Mekeypore-Santak-Nazira ML (Area: 77.0 sq km, with effect from to ) Major tectonic elements of the basin are: Assam Shelf, Naga Schuppen belt and Assam- Arakan Fold belt. The basin is bounded on the north and west by the Brahmaputra River and on the south and east by the Indo-Burma Ranges. The Assam Shelf is being over thrust by the Himalayas on the northwest and by the Burma micro-plate on the southeast. Structurally, the Assam Arakan Basin consists of two primary, sub parallel features trending southwest to northeast, which developed just prior to, and as a result of plate collision. The northernmost structural feature is the Assam Shelf, which is presently being subducted beneath both the Eurasian plate to the north and northwest and the Burma plate to the southeast. The southernmost feature consists of en-echelon folds of the Naga Hills over-thrust belt and northernmost Indo-Burmese Range, which are continually developing as the shelf is subducted further. The general geology of the area is well known from subsurface and outcrop data. The stratigraphic column consists of Archean metamorphic Basement overlain by Jaintia Group of Paleocene to Eocene age consisting of Tura, Sylhet and Kopili formations. The Jaintia Group is overlain by the Barail Group of sediments consisting of Disangmukh, Demulgaon and Rudrasagar formations of Eocene to Oligocene age and underlain by Tipam Group of Miocene to Pliocene age consisting of Geleki sandstone, Lakwa Sandstone, Girujan clay and Nazira Sandstone. Moran Group of younger sediments of Plio-Pleistocene to Recent age, comprising of Namsang, Dhekiajuli formations and Alluvium overlies the Tipam Group. Reservoirs in different stratigraphic levels starting from various sand units of Barail Group (BMS, BCS sands) to sands within Tipam Group (TS-6, TS-5, TS-4, TS-3, TS-2 & TS-1) have been charged in different part of the MLs depending on favorable entrapment conditions. Shales/Claystones of within these formations and clays in Girujan & Namsang have acted as cap 2

28 rock facies. Based on evaluation of G & G data of the ML areas, the following locations have been identified for exploratory drilling: 1) GKBT, 2) GKBS, 3) MKAD & 4) NGAB. 1.2 Technical Justification for Released Locations 1 GKBT: The location GKBT falls in a separate fault block towards the southeast of the main Geleki field. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4, TS-5). The location is to be drilled to a depth of 2975m (MD) and is technically viable. The details of the location are given below. Sl N o Prospect Location Name PEL-ML Categ ory TD (m) MD Loc. Reference Latitude / Longitude of Surface position. Objective 1 SOUTH GELEKI GKBT GELEKI -ML Expl., B-cat 2975 Lat: N Long: E TS-4 & TS-5 Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel 2. GKBS: The location falls in the extreme south of the SE-Geleki ML. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4 & TS-5 pays). The location is to be drilled to a depth of 2900m (MSL) and is technically viable. The details of the location are given below. Sl N o 2 Prospect SOUTH GELEKI Location Name GKBS PEL-ML SE GELEKI -ML Categor y Expl., B-cat TD (m) MD 3000 Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel Loc. Reference Latitude / Longitude of Surface position. Lat: N Long: E Objective TS-4 & TS-5 3

29 3. MKAD: The location MKAD is mapped as a fault closure at LCM and Tipam (TS-5) levels. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4 & TS- 5 pays). The location is to be drilled to a depth of 3075 m (MSL) and is technically viable. The details of the location are given below. Sl N o 3 Prospect MEKEY- PORE Location Name MKAD PEL- ML Category Expl., B-cat TD (m) MD 3175 Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel Loc. Reference Latitude / Longitude of Surface position Lat: N Long: E Objective TS-4 & TS-5 4. NGAB: The location NGAB is mapped as a fault closure at LCM. G&G studies carried out suggests possible presence of hydrocarbons in Tipam Formations (TS-4). The location is to be drilled to a depth of 2925 m (MSL) and is technically viable. The details of the location are given below. Sl N o 4 Prospect NORTH GELEKI Location Name NGAB MK- SN- NZ- ML PEL- ML MK- SN- NZ- ML Category Expl., B-cat TD (m) MD 3025 Spheroid: WGS-84, Projection System: Lambert Conical Single Parallel Loc. Reference Latitude / Longitude of Surface position Lat: N Long: E Objective TS-4 The above locations have been firmed up to oil exploration and are likely to accrete inplace hydrocarbons to the tune of about 4.09MMT. This will result in increase of hydrocarbon production and further improvement of the country s economy. The locations are technoeconomically viable. 2.0 Details of proposed Drilling Activity ONGC owned electrical type E-2000 (BHEL Rig), which has a capacity to drill to the depth of 6000m is proposed to be deployed for undertaking drilling in the block. The technical details of the proposed drilling activities are given below: 4

30 Well location / Depth GKBS (Depth:2975m MD) GKBT ( Depth:3000m MD) MKAD (Depth:3175m MD) NGAB (Depth: 3025m MD) of wells to be drilled One One One One Duration of drilling 6-7 months 6-7 months 6-7 months 6-7 months Qty of drilling fluid cu.m 900m 3 900m 3 900m 3 900m 3 Qty. of cuttings, cu.m Appox m 3 Appox m 3 Appox m 3 Appox m 3 Qty. of drlg. Waste water, cu.m Location details (Surface position) Lat: 1400m m m m N Long: E Lat: N Long: E Lat: N Long: E Lat: N Long: E Distance of block boundary from coastline Onland location Onland location Onland location Onland location Development plan in case of strike HC reserve (initially in place) To be chalked out after hydrocarbon strike To be chalked out after hydrocarbon strike To be chalked out after hydrocarbon strike To be chalked out after hydrocarbon strike 1.07 MMT 0.96 MMT 1.19 MMT 0.87 MMT Formation pressure Hydrostatic Hydrostatic Hydrostatic Hydrostatic Test flaring, duration 2 to 3 days, Flare details: Confined to the oil pit. 2 to 3 days, Flare details: Confined to the oil pit. 2 to 3 days, Flare details: Confined to the oil pit. 2 to 3 days, Flare details: Confined to the oil pit. 5

31 2.1 Details of the drilling rig proposed to be deployed Type of rig Drilling mud composition Power generator type and no s Diesel consumption Qty. of fresh water requirement & source Manpower on rig Material requirement & Mobilization Details of solids handling system Details of sewage treatment facility, if any Waste pit availability & size 30m X 20m X 1.5m 30m X 20m X 1.5m 40m X 30m X 1.5m Oil pit availability & size Electrical rig Water based drilling fluid AC-SCR type. Four no s 200 litres/hour 2000m3. Transported from nearby source through contractor. 30 person / 12 hrs shift From ONGC base, Sivsagar Shale shakers GPM capacity Desander GPM capacity Desilter-1200 GPM capacity t applicable 25m x 10m x 1m 2.2 Drilling Operations Only water based drilling mud will be used. The quantity of drill cuttings generated will be around m3. The quantity of wastewater produced will be about 15 m3/day. The rig will be provided with solids handling system comprising Shale shakers (1200 GPM), de-sander (1200 GPM) and de-silter (1200 GPM) and Degasser with vacuum pump. Drilling operations will be carried out using an electrical type drilling unit (Drilling Rig) for drilling of oil and gas wells. It consists of a derrick, at the top of which there is a crown block and a hoisting block fitted with a hook. From the hook a swivel a Kelly stem is suspended passing through a square or hexagonal Kelly bush which fits into the rotary table. The rotary table receives the power from an electric motor. The electric motor rotates the rotary table which passes through the Kelly bush and the rotations are transmitted to the bit as the drilling progresses, the drill pipe in singles are added to continue the drilling process. At the end of the bit life, the drill pipes are pulled out in stands and stacked on the derrick platform. A stand normally has 3 single drill pipes. After changing the bit, the drill string is run back into the hole and further drilling is continued. This process continues till the target depth is reached. During the course of drilling, cuttings are generated due to crushing action of the bit. These cuttings are removed by flushing the well with duplex/triplex mud pumps. The mud from the pump discharge through the rotary hose connected to stationary part of the swivel, the drill string and bit nozzles. The mud coming out of the bit nozzles pushes the cuttings up hole and transports them to the surface through the annular space between the drill string and the hole. The mud not only carries away crushed rock from the bottom of the hole but it also cools the bit as it gets heated due to friction with formation while rotating. The mud also helps in balancing subsurface formation pressures and by forming a cake on the walls of the well diminishes the possibility of crumbling or caving of the well bore. At the surface, the mud coming out from well along with the cuttings falls in a trough, passes through the solids control equipments i.e. shale shaker, de-sander and de-silter. These equipments remove the solids of different sizes which get mixed with the mud during the course of drilling. The cleaned mud flows back to the suction tanks to be again pumped into the well. The drilling mud/fluid circulation is thus a continuous cyclic operation. The most suitable clay for mud preparation is bentonite which is capable of forming highly dispersed colloidal solutions. Various other chemicals are 6

32 also used in mud preparation as per requirements dictated by the temperature/pressure conditions of the wells. The mud is continuously tested for its density, viscosity, yield point, water loss, ph value etc. to ensure that the drilling operations can be sustained without any down hole complications. 2.3 Drilling Facilities Drilling is a temporary activity which will continue for about 6-7 months for each well in the block. The rigs are self-contained for all routine jobs. Once the drilling operations are completed, and if sufficient indications of hydrocarbons are noticed while drilling, the well is tested by perforation in the production casing. This normally takes 2-3 days. If the well is found to be successful hydrocarbon bearing, it is sealed off for future development. If no commercial hydrocarbon is struck, the well is abandoned according to existing safety norms. 2.4 General Requirements of Drilling a. Drilling muds Exploratory drilling programme requires the following common facilities: Drilling of wells requires specially formulated muds which basically comprise inert earth materials like bentonite, barite in water with several additives to give mud weight, fluidity and filter cake characteristics while drilling. The drilling muds have several functions like lubrication and cooling of the drill bit, balancing subsurface formation, bringing out the drill cuttings from the well bore, thixotropic property to hold cuttings during non-operations, formation of thin cake to prevent liquid loss along well bore etc. Several additives are mixed into the mud system to give the required properties. Water based mud will be used to the possible extent in exploratory drilling but use of synthetic based mud may require due to complexities associated with the geological formations and associated hole stability problems. The constituents of water based mud (WBM) are given in Table 1.2. The special additives and their functions in WBM are shown in Table 1.3. b. Power Generation The drilling process requires rotation of drill bit through the draw works which require power. The power requirement of the drilling rig will be met by using the four diesel generator sets with a diesel consumption of about 4.8 Kl / day. The exhaust stacks of the DG sets are likely to vent the emissions. c. Water requirements The water requirement in a drilling rig is mainly meant for preparation of drilling mud apart from washings and domestic use. While the former consumes the majority of water requirement, the water requirement for domestic and wash use is very less. The daily water consumption will be 25 m3/d of which 15m3/d will be used for mud preparation and 10m3/d will be used for domestic purposes including drinking. d. Domestic wastewater The operating personnel in the drilling rigs will operate mostly from nearby ONGC colonies. However suitable soak pits will be available at the drilling site. e. Solids removal 7

33 The rock cuttings and fragments of shale, sand and silt associated with the return drilling fluid during well drilling will be separated using shale shakers and other solids removal equipment like desanders and de-silters. The recovered mud will be reused while the rejected solids will be collected and discharged into the waste pit. f. Drill cuttings and waste residual muds During drilling operations, approx m3 per well of wet drill cuttings are expected to be generated from each well depending on the type of formation and depth of drilling. In addition to the cuttings m3/day of wastewater is likely to be generated during well drilling. The waste residual muds and drill cuttings which contain clay, sand etc. will be disposed into the waste pit. g. Testing Testing facilities will be available at drilling rig for separation of liquid phase and burning of all hydrocarbons during testing. The test flare boom will be located at a distance from the drilling rig. h. Chemical storage The drilling rig will have normal storage facilities for fuel oil, required chemicals and the necessary tubulars and equipment. The storage places will be clearly marked with safe operating facilities and practices. i. Manpower The drilling rig will be operated by approx. 30 persons on the rig at anytime. The manpower will operate in two shifts with continuous operations on the rig. j. Logistics Crew transfers to and from the drilling rig, materials, diesel and chemicals will be through light vehicles, trucks and trailers. 3.0 Investment anticipated The anticipated cost of drilling of wells (which includes the PEL fees, EIA study, stacking of the location, land acquisition, site preparation and drilling activity has been tabulated below. Sl. Name of the locations Investment anticipated 1 GKBS Approximately 40 Crores 2 GKBT Approximately 40 Crores 3 4 MKAD NGAB Approximately 40 Crores Approximately 40 Crores 3.1 Justification for Environmental Clearance Geleki ML is highly prospective where oil and gas have been discovered and produced from a large stratigraphic column ranging from Pre-Barails to Girujan Formation. However there are 8