Pre-Feasibility Report

Transcription

1 Pre-Feasibility Report On Development Drilling of 31 Wells and establishment of Early Production System (one) at Nagayalanka in the Onland NELP-V Block KG-ONN-2003/1, Andhra Pradesh 2014 Oil and Natural Gas Corporation Ltd. (A Govt. of India Enterprise), Rajahmundry Asset Rajahmundry

2 Pre-Feasibility Report On Development Drilling of 31 Wells and establishment of Early Production System (one) at Nagayalanka in the Onland NELP-V Block KG-ONN-2003/1, Andhra Pradesh 1.0 Introduction The onland Block KG-ONN-2003/1 was awarded to the Consortium of Oil and Natural Gas Corporation Limited (ONGC), Cairn Energy India PTY Limited (CEIL) and Cairn Exploration (No.4) Limited (CE4L) under NELP Round-V in Participating Interests (PI) were 51%, 24% and 25% respectively with CEIL being the Operator in the Block. PEL for the Block was granted on In 2008, CE4L assigned its entire PI to Cairn India Limited (CIL). Subsequently, CEIL also assigned its entire PI to CIL and also obtained approval for transfer of Operatorship in favor of CIL in Currently, the consortium partners in the Block are ONGC and CIL with PI of 51% and 49% respectively. ONGC is the Operator during Development and Production Phase w.e.f The Block area is geographically located in the southern part of Krishna-Godavari Basin, near the mouth of the Krishna River and falls mostly within the Krishna District and a small part within Guntur District in the State of Andhra Pradesh. The Minimum Work Programme (MWP) of the Block during Exploration Phase of 7 years (Phase-I of 3 years, Phase-II and III each of 2 years duration) entailed 2D and 3D seismic data acquisition, processing & interpretation, geochemical sampling & study and drilling of eight Exploratory Wells (5 in Phase-I, 1 in Phase-II and 2 in Phase-III). The MWP for the Exploration Phase has been completed and two commercial hydrocarbon pays viz. Raghavapuram Pay and Gollapalli Pay have discovered during Phase-I and Phase-II activity respectively. The commerciality of these discovered oil and gas reserves has been further substantiated through an appraisal work programme (Appraisal Phase) wherein drilling and testing/assessment of two appraisal wells were completed. In view of the discoveries made, the Block entered Appraisal Phase (without entering Phase-III of the Exploration Phase). The discoveries have been reported to DGH/MoPNG through Declaration of Commerciality (DoC) reports submitted on and respectively for the Raghavapuram and Gollapalli pays. The DoCs have been reviewed by GoI on and Field Development Plan (FDP) is under preparation. The two pays viz. Gollapalli and Raghavapuram, occurring within close temporal proximity and having similar spatial distribution of prospective areas, will be developed jointly, through an integrated approach, for robust techno-economic viability. Asset HSE, Rajahmundry Asset Page 2

3 Table 1: Project Summary Name of the Project Block Area Geographical Location No. of Wells Target Pay Horizons Hydrocarbon Reserves Total cost of the Project Details of the Locations and Location map Development drilling of 31 wells and establishment of Early Production System (one) at Nagayalanka in the onland NELP-V Block KG-ONN-2003/1, Andhra Pradesh 315 sq km (Discovery area) Nagayalanka area (falls mostly in Krishna District and small part in Guntur District of Andhra Pradesh) 31 Nos 2 (Gollapalli and Raghavapuram) In-place: OIIP: 292 MMbbl; GIIP: 524 BCF Rs Crores Coordinates of Discovery area at Table 3, (Location of individual wells to be finalized) 2.0 Details of the Block KG-ONN-2003/1 The awarded Block KG-ONN-2003/1 encompasses an area of 1697 sq km and located in the southern part of Krishna-Godavari Basin, near the mouth of the River Krishna. At the end of Phase-I activity, an area of 435 sq km was relinquished; on completion of Phase-II activity another 947 sq km was relinquished. The remaining area of 315 sq km (Discovery area) has been retained for development drilling and production activities. ONGC is the Operator for the Block w.e.f for the Development and Production Phase. Block Details: Block Name : KG-ONN-2003/1 NELP Round : V JV Partners : ONGC 51%, CIL 49% Operator for the Block : ONGC (Development & Production Phase) PSC signed on : Effective Date of PEL : Development Area : 315 sq km (Discovery area) 2.1 Geological Setting The Krishna-Godavari Basin is a NE-SW trending pericratonic basin situated on the eastern continental margin of India. The KG-ONN-2003/1 Block is located in the West Godavari sub-basin of this Krishna-Godavari Basin and geographically in close proximity to the mouth of the River Krishna. Structurally, the Block area contains a number of rotated fault blocks separated by half-grabens which are arranged in an en-echelon manner and offset by major cross-faults. Stratigraphically, the Gondwana sediments of Carboniferous-Permian-Triassic age rest unconformably on the Pre-Cambrian Archaean basement. The Late Jurassic-Early Cretaceous sequence began with the sand-dominated Gollapalli Formation in the West Godavari sub-basin. The Gollapalli Formation comprises of a series of stacked micaceous and gritty sandstones. The overlying Raghavapuram Shale represents the first significant marine transgression. This shale thins westwards and onto the structural Asset HSE, Rajahmundry Asset Page 3

4 highs in the basin, where significant sandstones, including the Raghavapuram Sandstone, have developed. Bantumilli and Tirupathi Sandstones are of Late Cretaceous age. These are overlain by the Tertiary sediments. 3.0 Exploration Activities and Data Acquisition During the pre-nelp Era, three wells were drilled by ONGC in Nagayalanka area. The wells, however, were all dry. Consequent to the award of the Block KG-ONN-2003/1 to ONGC-CIL consortium during NELP-V, Exploration Phase work is completed. 3.1 Work Done in Exploration Phase During the Exploration Phase, 2D and 3D seismic data acquisition, processing & interpretation, geochemical sampling & study and exploratory drilling were carried out. 5 wells were drilled during Phase-I, 1 well during Phase-II and 2 wells during the Appraisal Phase. Summary of work done is mentioned under Table 2. Table 2 Work done in the Block KG-ONN-2003/1 during each Phase Phase Actual Work Done Remarks Pre-NELP wells Phase-II Phase-I Drilled 3 wells Bubbarlanka-1, Bhavadevarapalli-1, Mantripalem-1 a) API of 523 LKM 2D seismic data b) Reprocessed 1697 LKM 2D seismic data c) API of 255 SKM 3D seismic data d) Collected 500 Geochemical samples and studied e) Drilled 5 Exploratory wells Nagaram-1, Daliparu-1, Lankapalle-1, Krishna-1, Nagayalanka-1/ Nagayalanka-1z a) Reprocessed 328 LKM 2D seismic data b) Reprocessed 255 SKM 3D PSDM data c) Drilled 1 Exploratory well Nagayalanka-SE-1 Wells dry and abandoned a) Nagayalanka-1z Raghavapuram Discovery b) Other 4 wells dry and abandoned c) Relinquished 435 sq km area a) Nagayalanka-SE-1 Gollapalli Discovery b) Identified and retained 315 sq km area as the Nagayalanka Discovery area. Relinquished remaining 947 sq km area Appraisal Phase a) Drilled 2 appraisal wells Nagayalanka-1z-ST, Nagayalanka-NW-1z a) Nagayalanka-1z-ST produced oil and gas from Gollapalli and Raghavapuram pay sands. Extended well testing (EWT) also carried out. b) Other well dry and abandoned Asset HSE, Rajahmundry Asset Page 4

5 Phase-III - Phase-III Not entered 4.0 Hydrocarbon Discoveries Raghavapuram Sandstone and Gollapalli Sandstone are the two discovered hydrocarbon bearing pay zones in the block which have been identified during Phase-I and Phase-II activity respectively. These two potential reservoirs occur within the Cretaceous sequence. Submission of Declaration of Commerciality (DoC) Report i) DoC for Nagyalanka-1z Discovery (Raghavapuram Pay) submitted on ; ii) DoC for Nagayalanka-SE-1 Discovery (Gollapalli Pay) submitted on The DoCs have been reviewed by GoI on and Field Development Plan (FDP) is under preparation. 5.0 Project Description 5.1 Description of Contract Area Project Region Block Title Block Area (sq km) Remarks Onland area mainly in Krishna District and small part in Guntur District of Andhra Pradesh KG-ONN-2003/1 315 Table 3 for coordinates of the Discovery area for development drilling Table 3 coordinates of the Discovery Area (315 sq km) Point UTM44N Projection GCS WGS1984 X Y Longitude Latitude E N E N E N E N E N E N E N E N Asset HSE, Rajahmundry Asset Page 5

6 5.2 Proposed Project Based on the Geological, Geophysical studies and results of production testing during the exploration and appraisal phases, the Block has been assessed to have distinct commercial prospects from two hydrocarbon pays viz. Gollapalli and Raghavapuram sandstones. Accordingly, the block is planned to be developed in a phase wise manner through drilling of 31 wells. Out of these 31 wells, 30 are horizontal and 1 is vertical wells. As the pays are tight in nature, hydraulic fracturing within these sands will play a pivotal role in bringing the wells on production. 3-4 shallow wells for effluent disposal are also planned. The wells are to be brought under production consequent to creation and connection to an Early Production System (EPS). Successful commercial exploitation of these two hydrocarbon pays will augment the production of oil and gas under the present scenario of ever growing demand of oil and gas in the country. 5.3 Project Investment The cost of drilling including rig hiring, daily drilling rates, consumables, well accessories, hydraulic fracturing, land acquisition with respect to drilling of 31 wells is envisaged to be Rs crores. Out of these 31 wells, cost of 30 horizontal wells is envisaged to be Rs and cost of 1 vertical well is envisaged to be crores. The cost for the establishment of the EPS is envisaged to be Rs crores. Therefore, the total project cost comes to Rs crores 5.4 Project Justification The Long term production profile envisages bringing 6 wells online annually and ramping up production to a peak of 13,200 STB/ Oil and 54.8 MMSCF/d Gas till year and thereafter declining gradually to 3550 bbl/d Oil and 6.3 MMscf/d Gas by March, It is estimated that cumulative 39.1 MMbbl Oil and 70.1 Bcf Gas will be recoverable. Techno-economic analysis of the proposed combined development strategy of the Raghavapuram and Gollapalli pays in Nagayalanka field, having a Project NPV of approximately Crores and IRR of 38%, indicates a healthy project and potentially justifiable for commerciality to deliver positive investment returns exceeding the cumulative contract costs given technically justifiable assumptions regarding reservoir performance, development cost, operating cost and oil price projection. 6.0 Development Strategy The Nagayalanka discovery is a deep, tight reservoir (depth >4000 m) having ambient reservoir conditions of Celsius temperature and psi formation pressure and classifies as a High-Pressure High-Temperature (HPHT) development. Exploiting such reservoirs are technically challenging - the best possible approach is to develop the field in a series of phases guided by acquired data from previous phases. The drilling of inclined wells or horizontal wells from few clusters targeting multiple pays, after examining their techno-commercial feasibility, are also envisaged to further Asset HSE, Rajahmundry Asset Page 6

7 improve the economics and mitigate LAQ issues. Hydraulic fracturing is essential to commercially flow these discoveries as both the reservoirs have very poor permeability. Considering both the pays are very close to each other vertically, commingled flow of the hydrocarbons is also envisaged. A common surface facility - Early Production System (EPS) will be established to cater to the extraction and delivery of the hydrocarbons. 7.0 Transportation of Oil and Gas for Marketing The produced Oil along with the associated Natural Gas are both marketable commodities. Purified condensate/oil will be transported by road tankers to unloading station of ONGC at S- Yanam for further transportation to M/s HPCL, Visakhapatnam. Gas will be compressed and its evacuation will be done by the marketing tie up. 8.0 Technological Aspects Technological aspects include operations related to drilling, cementing, logging, stimulation and testing. 8.1 General Aspects of Drilling Drilling operations will be carried out using an electrical type / VFD (Variable Frequency Drive) drilling rig. The rigs are self-contained for all routine jobs. Drilling is likely to continue for about 3-4 months for each well in the Block. Drilling unit for drilling of oil and gas wells consists of a derrick at the top of which is mounted a crown block and a hoisting block with a hook. From the swivel is suspended a kelly stem which passes through a square or hexagonal kelly bush. This kelly bush fits into the rotary table. The rotary table receives the power to drive it 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 the hole and transports it 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 cuttings falls in a trough, passes through the solids control equipment i.e. shale shaker, de-sander and de-silter. These Asset HSE, Rajahmundry Asset Page 7

8 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. Thus, drilling mud/fluid circulation is a continuous cyclic process. The most suitable clay for mud preparation is bentonite which is capable of forming highly dispersed colloidal solutions. Various other chemicals are also used as per requirements dictated by the subsurface temperature/pressure condition in wells. The mud is continuously tested for its density, viscosity, yield point, water loss, ph etc. to ensure that drilling operations can be sustained without any down hole complications. Once drilling operations are completed for each stage, casings are lowered and cemented. Well is tested after making holes (perforations) in the production casing. Production testing normally takes few days for each identified object. Finally, the well is connected to a production installation (EPS) and put on regular production. 8.2 Drilling Operations Salient features of the proposed drilling activity are given below under Table 4. Table 4 Information on Drilling Activity Well location / Depth Description No. of wells to be drilled 31 Duration of Drilling 3-4 months for each well Qty. of drilling fluid cu. m. About m3 for each well Qty. of drill cuttings, cu. m m3 for each well Qty. of drlg. Waste water, cu. m m3 for each well Location Details Locations to be finalized Distance of Block boundary from the coast Onland Locations line Formation pressure psi Formation Temperature Celsius Test flaring duration 1 to 3 days for each object Flare Details: Confined to the oil pit. Flare stack of sufficient height located at a safe distance from the well mouth Hired electrical type rigs with capacity to drill to ~5000 m are proposed to be deployed. It is envisaged that two such rigs will be under simultaneous deployment. Type of rig and associated requirement are mentioned under Table 5. Table 5 Drilling Rig Type and associated infrastructure requirement Description Type of rig Drilling mud composition Details 2000 HP/ Electrical Rig (Type-III) preferably VFD Rig with top drive Water based Drilling Fluid till ~450 m (26 hole); SOBM for the remaining section till TD (~4700 m). Asset HSE, Rajahmundry Asset Page 8

9 Power generator type & nos. Diesel consumption Quantity of fresh water requirement and source Manpower on rig Material requirement & Mobilization Solids handling system on rig Sewage treatment facility, if any Quantity of waste water produced Waste Pit availability & Size Oil Pit availability & Size AC SCR Type (6 3-4 kl / day per day per well 1000 m3. To be transported from nearby source through contractual services As per Contractor s Policy To be provided by the Contractor Shale Shakers 1200 GPM Capacity De-sander 1200 GPM Capacity De-silter 1200 GPM Capacity Not applicable m3/d 30 x 33 x 5-2 Nos 38 x 33 x 5 1 No. 23 x 20 x 5 1 No. 3 x 3 x 4 1 No. The quantity of drill cuttings generated will be around m 3 from each development well. The quantity of wastewater produced will be about m 3 /day. The rig will be provided with solids handling system comprising shale shakers, de-sander and de-silter for cutting and fines handling and a degasser with vacuum pump for making the drilling fluid free from gas bubbles, if any. The Mobile ETP will be installed to process the drill site effluent, so as to deliver treated wastewater having the desired characteristics of treated effluent as per the standards laid down by the APPCB The well configuration will be telescopic, diameter decreasing with depth. The following general well architecture is envisaged. Depth Well Diameter Casing Size Surface - 30 m m m 17½ 13 3 / m 12¼ 9 5 / m 8½ 7 Liner m 6 4½ The actual depths and casing policy may vary according to actual subsurface geological position and formation pressures. The casings will be cemented with oil well cement slurry of sufficient compressive strength pumped within annular space between the open hole and the casing. 8.3 General Requirements of Drilling Development drilling programme requires the following common facilities: a. Drilling muds Drilling of wells requires specially formulated muds which basically comprise of inert earth materials like bentonite, barite in water with several additives to give mud weight, fluidity and filter cake characteristics while drilling an oil / gas well. The drilling muds have several functions like lubrication and cooling of the drill bit, balancing subsurface Asset HSE, Rajahmundry Asset Page 9

10 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 muds (WBM) are generally used for drilling. Specially designed synthetic oil based muds (SOBM) are used under certain special conditions, particularly during drilling difficult formations when encountered. Synthetic based mud systems are proven to be highly efficient and eco-friendly in tackling difficult hole problems due to their high fluid stability, greater shale inhibition and lower torque/drag values. Such synthetic muds are being used worldwide in drilling operations. The constituents of water based mud (WBM) are given in Table 6. The special additives and their functions in WBM are shown in Table 7. Table 6 Ingredients of Water Based Drilling Fluid Sl. No. Chemicals 1. Barite 2. Bentonite 3. Carboxy Methyl Cellulose 4. Mud Thinner / Conditioner 5. Resinated Lignite 6. Non-Weighted Spotting Fluid 7. Weighted Spotting Fluid 8. EP Lube 9. Drilling Detergent 10. Caustic Soda 11. Potassium Chloride 12. Soda Ash Table 7 Special Additives and their Functions in Water-based Drilling Fluids Sl. No. Chemicals Function 1. Sodium bicarbonate Eliminate excess calcium ions due to cement contamination 2. Sodium chloride Minimize borehole washout in salt zone 3. Groundnut shells, mica Minimise loss of drilling mud to formation of cellophane 4. Cellulose polymers or starch Counter thick, sticky filter cake, decrease filter loss to formation 5. Aluminium 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 drilling string. Pill is placed down hole opposite contact zone to free pipe SOBM is low toxic synthetic oil, paraffinic in nature. The oil is converted into a strong emulsion by addition of additives to withstand the rigours during circulations/drilling. Asset HSE, Rajahmundry Asset Page 10

11 Synthetic based muds are biodegradable with very low toxicity and are specially developed to be environment friendly. Proper handling of SOBM is essential to avoid wastage or discarding of the mud. The drill cuttings are collected after shale shaker and dried before disposal in an isolated pit with impervious lining and are buried thereafter. Fine screen is used for SOBM mud and the screen should be oil wet. In general, SOBM system is used after drilling of top hole. In the present project, drilling with water based mud (WBM) may be carried out till the surface casing (26 hole) and SOBM used thereafter. For drilling the wells, SOBM having aromaticity of <1% will be used. SOBM services will be implemented through contractual hiring of authorised / certified service provider. The drilling cuttings will be collected, washed, treated thoroughly and discarded as per guidelines on disposal of such solid waste. Unused SOBM will be collected and treated for reuse / recycle by the service provided as per prevalent norms. The constituents of a Synthetic Oil Based Mud (SOBM) are given in Table 8. Table 8 Ingredients of Synthetic Oil Based Mud (SOBM) Sl. No. 1. Biocide 2. Oxygen Scavenger 3. Cellulose Fibre 4. Corrosion Inhibitor 5. Solvent Cleaner 6. Spotting Fluid 7. Surfactant- Cleaner 8. Zinc Carbonate 9. Synthetic Graphite 10. Oil wetting Agent 11. Rheology Modifier 12. Thinner Chemicals 13. Calcium Carbonate (Coarse/Medium/Fine) 14. Emulsifier 15. Viscosifier 16. Fluid Loss Reducer Remarks: Sl. No are High Pressure and High Temperature additives b. Power Generation The drilling process requires movement of drill bit through the draw works which require power. The power requirement of the drilling rig will be met by using the AC SCR Type (6 Nos) Diesel Generator sets with a diesel consumption of about 3-4 kl/day. The exhaust stacks of the DG sets are likely to vent the emissions. Asset HSE, Rajahmundry Asset Page 11

12 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 around 25 m 3 /d of which 15 m 3 /d will be used for drilling purposes including mud preparation and 10 m 3 /d will be used for domestic purposes including drinking. During drilling with SOBM, requirement of water will be less. d. Domestic wastewater The operating personnel in the drilling rigs will operate from drill site accommodation (DSA) in the vicinity of the location. Suitable soak pits will be available at the DSA. 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-sander and de-silter. The recovered mud will be reused while the rejected solids will be collected and discharged into the waste pit. When SOBM is used, the cuttings will be collected, dried and buried. Use of de-sander and de-silter will be avoided during SOBM use. f. Drill cuttings and waste residual muds During drilling operations, approx m 3 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 m 3 /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. When SOBM is used, disposal of the cuttings needs to be buried in an isolated pit after drying. g. 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. h. Manpower The drilling rig will be operated by approx persons on the rig at any point of time. For charter-hire rigs, the manpower may vary as per the Contractor s policy. The manpower will operate in two shifts with continuous operations on the rig. i. Logistics Crew transfers to and from the drilling rig, materials, diesel and chemicals will be through light vehicles, trucks and trailers. 8.4 Brief on well logging Open hole logging is carried out during various phases of drilling. Open hole logging normally includes recording of resistivity, gamma ray, density, neutron, sonic logs and Asset HSE, Rajahmundry Asset Page 12

13 other special logs as necessary. Cased hole logging includes recording of gamma, neutron, and cement bond evaluation logs. Perforation of object is done with gamma correlation. During production phase, periodic production logging is necessary. 8.5 Perforation After casing and cementation, the well bore to formation communication against the identified target objects (pays zones) is made by perforating the casing with help of controlled explosives. 8.6 Stimulation During stimulation, around 2400 to 3200 bbl gel with proppant sand is planned to be pumped within each object in the well. For preparation of gel, water from nearby sources will be transported by hired water tankers. 8.7 Well activation and Testing Required 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. 9.0 Production Facility An Early Production System (EPS) for handling the produced oil and gas is planned to be constructed at a suitable location depending on availability of land and approachability from all well sites. The location of the Nagaylanka EPS will be the wells site Nagayalanka #1Z-ST. It is expected that wells will be connected to the EPS. This EPS, with a handling capacity of 800 m3/d of Oil and 5,00,000 SCMD of Gas, will have well pads with gathering manifold and well fluid transfer line, HP and LP separators and Heater-treater followed by gas dehydration (dehydration unit) for gas processing, storage tank for oil storage prior to transfer to an oil terminal, oil pumps, gas compressors etc. Intra-field pipeline network will be connecting the wells to the EPS. Purified condensate/oil will be transported by road tankers to unloading station of ONGC at S- Yanam for further transportation to M/s HPCL, Visakhapatnam. The stabilised oil can be shipped using Single Buoy Mooring (SBM). Gas will be compressed and its evacuation will be done by the marketing tie up. The associated produced water will be treated in ETP and further disposal of treated effluent will be carried out by sub-surface injection in a well below a depth of 1000 meters from the ground level. The treated effluent requires complying with the parameters with respect to suspended solids and, oil/grease; limits being 100 mg/l and 10 mg/l respectively and also with other permissible limits as per MoEF standards for Oil Drilling and Gas Extraction Industry specified under Schedule I in The Environment (Protection Rules), Ambient Air Quality Monitoring Ambient Air Quality Monitoring to be carried in and around the drill sites and EPS regularly. Asset HSE, Rajahmundry Asset Page 13