GAS INJECTION IN CUSIANA & CUPIAGUA FIELDS COLOMBIAN FOOTHILLS

Transcription

1 GAS INJECTION IN CUSIANA & CUPIAGUA FIELDS COLOMBIAN FOOTHILLS by FABIAN A. TORRES The 22 nd CO2 Conference at Midland, TX 12/08/16

2 Preliminary Note on Intellectual Authorship This brief presentation about gas injection experience in some fields of Colombian Foothills evidence teamwork, participation and interaction of several professionals for over 20 years ( ), actively involving: Fluid Characterization: 1. Raul Osorio Gallego - PVT and Fluids Characterization, Ecopetrol 2. Sheng-Tai Lee* - PVT Expert, British Petroleum 3. Professor Curtis H. Whitson - Consultor, Norwegian University of Science and Technology 4. Professor Ali Danesh* - Consultor, Heriot-Watt University 5. Proffessor Abbas Firoozabadi - Consultor, Yale University - RERI 6. Wilson Barrios - Former PVT Lab Leader, ICP Development Strategy and Operation: 1. British Petroleum Company: BP Exploration Company Colombia - BP Energy Company Colombia 2. Equion Energía 3. Ecopetrol S.A 2 * R.I.P.

3 Outline General Information Data Acquired Wells, Lines & Gas Process Facilities Strategy Gas Injection Optimization Results Main Challenges - Lessons Learned 3

4 General Information - Location FLOREÑA Laguna de Tota PAUTO COMPLEX RECETOR YOPAL Recetor CUPIAGUA Aguazul Tauramena CUPIAGUA SUR Lean Gas Condensate Rich Gas Condensate Casanare, Colombia 175 Km northeast from Bogotá Foothills of Colombian Andes CUSIANA Volatile Oil Km Km 4

5 General Information Three naturally fractured sandstone reservoirs (main + 2 secondary layers) Asymmetric tight anticline NE-SW elongated Commingled production / injection Average depth = ft / ft (TVDss) Structurally complex reservoirs: Thrust faulting Imbricate inverse faults Minor intra reservoir faults Fluid system: volatile oil + rich condensate gas cap / rich condensate gas Cusiana Structure WELL01 Cupiagua Structure WELL02 WELL03 WELL04 Main Fm. Secondary Fm. Secondary Fm. Average initial reservoir pressure: ft TVDss / ft TVDss Reservoir temperature: F Reservoir permeability: md Reservoir porosity: 2-12 % Main Fm. Secondary Fm. Secondary Fm. WELL01 5 Early secondary recovery via lean gas miscible reinjection as main production mechanism

6 General Information - Fluid Systems INITIAL GAS INJECTION INITIAL GAS INJECTION Volatile oil + rich gas cap ( STB/MMSCF) Very rich gas condensate ( STB/MMSCF) Relatively small near critical transition zone ( 100 ft) Near critical fluid over 6000 ft. HC column High compositional variation ( stb/scf) Small compositional variation. Early crestal injection in main reservoir / late crestal injection in secondary reservoirs. Early crestal injection in main reservoir / late crestal injection in secondary reservoirs API, reservoir conditions API, reservoir conditions 6 Unique fluid system in the world!

7 General Information - Fluid Systems Depth Pressure (psia) Maximum liquid recovery from gas cap and oil leg will be achievable through considerable gas reinjection and recycling. Process enhanced by: CUSIANA Swelling due to gas solubility above MMP. High reservoir 240 temperature and pressure 10750'ss will Psat P(Reserv oir) contribute to condensate (Dew) revaporation below MMP. Partial pressure 260 maintenance depending on areal gas injection distribution. CUPIAGUA Reservoir Temperature ( o F) First contact miscibility above Psat. 300 Well C Well A 14975'ss Below Psat, 310high reservoir temperature and pressure will contribute 5000 to condensate revaporation 6500 in contact 7000 with reinjected gas throughpressure multiple (psia) contacts. 2 1 Pressure (psia) 6,000 5,500 5,000 4,500 4,000 3,500 3,000 1 FIRST YEARS Figure 2 Cupiagua Well Sample Pressure-Temperature Phase Diagram C* Reserv oir Condition Oil Saturation (%) 2, Temperature ( o F) Temperature ( F) 0 2 MOST OF PRODUCTIVE LIFE OF FIELD Partial pressure maintenance depending on areal gas injection distribution. 7

8 Data Acquired - Key PVT Testing Main miscibility processes driven by gas/liquid mass transfer trough swelling (above MMP) and revaporation (below MMP) GAS SWELLING TEST* MULTIPLE CONTACT TEST* (forward/backward) INJECTION GAS V1 V1 L1 V2 L2 Vn CRUDE CRUDE CRUDE Ln Forward Contacts GAS INJECTION PSAT CCE L1 CRUDE INJECTION GAS V1 L1 INJECTION GAS V2 L2 INJECTION GAS Vn Ln (Backward) Swept-Zone Contacts INJECTION PSAT CCE Some adaptations needed to better understand related processes (e.g. adapted backward multiple contact test for oil revaporation, Vogel and Yarborough ). 8 * From: Phase Behavior - C. Whitson, M. Brulé

9 Data Acquired - Key PVT Testing Multiple Contact Test in Cusiana GAS PHASE AFTER FIRST CONTACT Backward test better describes involved phenomena. 9 MCT shows high efficiency at initial contacts. Process efficiency ( 60%) must be adjusted by sweep and areal efficiency to get maximum theoretical incremental volumes. GAS PHASE AFTER LAST CONTACT Cusiana backward MCT results

10 Data Acquired - Key PVT Testing Multiple Contact Test in Cupiagua Series 1 Series 2 Gas Injection Step Pressure Cumm. Gas Inj./ Mole Orig. Fluid Liq. Sat after Gas Removal Two different test configurations in order to completely understand revaporation phenomena: Series 1: pressure depletion + constant volume (not common). Series 2: constant pressure + constant volume. 10

11 Injected Gas BASE CASE % % % Injected gas corresponds to dehydrated separator gas Other gases used for sensitivity purposes No N2 or CO2 available for economically feasible EOR application 11 *Results from compositional numerical simulation model

12 Wells, Lines & Gas Process Facilities STAGE I STAGE II Production line Lean Gas Injection Separation Amine Plant Dehydration Compression General Gas Process Facilities Injection line Sales Gas Plant Due to commingled production and injection, completions must be designed for easy GSO/WSO, PLT/ILT etc. Easily converted depending on pad facilities availability. Maximum flexibility pipes to optimize gas injection strategy. Modular design will allow special adaptability to production/injection evolution and availability. Optimization function: Production Injection = Flare & Consumption Production Injection = Flare & Consumption + LPG/NGL + Gas Sales Typical Producer Well Schematic KEY POINT: The overall architecture was designed taking into account long-term vision to guarantee the change of strategy: STAGE I STAGE II, avoiding extremely expensive future modifications. Typical Gas Injector Schematic 12

13 Strategy 1. Crestal reinjection for gas cap expansion + flank / middle flank oil production. 2. Flank reinjection + middle flank recycling wells closed. 3. Flank producer wells converted to injectors + Middle flank producer wells reactivation + gas cap blowdown. 13

14 Gas Injection Optimization - Surveillance Data SURVEILLANCE ALTERNATIVE DIAGNOSED ISSUES SUBSEQUENT ACTIVITY WT Real Time WHT / WHP / inj rates PLT / ILT Tracers PBU / PFO / Static Gas recycling Lifting problems Crossflow Unefficient gas injection conformance Injectivity problems Compartmentalization Flow barriers Low / High transmissibility zones Skin damage Injectivity problems GSO / Foams CTGL / AutoGL / WSO WSO / partial isolation Foams / sand plugs / DH choke Hydraculic fracturing / Gas dispersible CHS / TTRD Numerical and analytical model updating History match tuning Hydraculic fracturing / Gas dispersible CHS / TTRD WHP FLP qg WHP FLP THP

15 Gas Injection Optimization - Analysis & Diagnosis Recycling pattern identification Real GOR vs depletion GOR (or yield) GOR as process tracer Fm.Date:2009/10 Mirador Date:2009/10 L-10 L-11 L-8 L-5 L-6 L-7 L-4 L-3 GOR C-28 L-2 C-36 C-15 C-42C-8 C-29 C-11 C-21 C-22 C-16 C-3 C-33 C-27 C-26 C-13 C-32 C-9C-23 C-18C-6 C-1 C-43 C-31 C-31RE C-40Z C-40 C-35 C-38 C-39C-24 C-2C-25 C-4 C-30 C-19 Delta GORRT Mv5 ( cf/bbl ) C-7 C-14 C-41 C-10L C-10 C-34 C-20 C-17 C-5 C-12 C-37 Mirador 15 Barco C-1 C-9 C-6 C-43C-1 C-31 C-31RE C-40Z C-40 C-35 C-38 C-39 C-2 C-4 C-30 C-19 C-7 C-14 C-41 C-10 C-20 C-17 C-12

16 Gas Injection Optimization mmscfd Asphaltene dissolution at reservoir level Partial GSO PW1 PW PW2 IW1 PW1 PW2 PW2 IW1 16 Asphaltene + recycling + conformance = inefficiency.

17 Strategy The development of the fields has been carried out in two stages: Development focused on early secondary oil recovery STAGE I Development focused on gas recovery STAGE II Drilling campaign + Crestal lean-gas injection Crestal lean-gas injection optimization + gas sales start-up Lean-gas injection at flank and midflank + Gas inj at secondary Fm Higher Gas sales + LPG/NGL generation Blowdown Miscible Lean Gas Reinjection Fluid Expansion Multiple Contact Revaporation 17

18 Strategy Results Cusiana Cupiagua 18

19 Main Challenges - Lessons Learned (Stage I) For Cusiana and Cupiagua fields, fluid system detailed understanding and their response to miscible gas reinjection implies understanding of over 70 % of total process, hence the importance of a correct PVT test design and EoS calibration. A good process understanding, associated efficiencies, heterogeneities and reservoirs dimension, makes it possible to identify areas in which optimal recovery can be reached. Prioritization strategies if required. A rigorous monitoring strategy based on identifying deviations from theoretical behavior allows for optimization measures even at early stages. A complete field development plan containing detailed strategies for each production stage will lead to optimal wells, flow lines and processing facilities design focused on cover most of the assets life. This way, investments can be efficiently apply reducing mid or late term additional CAPEX utilization. 19

20 20 Para uso restringido en Ecopetrol S.A. Todos los derechos reservados. Ninguna parte de esta presentación puede ser reproducida o utilizada en ninguna forma o por ningún medio sin permiso explícito de Ecopetrol S.A.