Secure Energy for America RPSEA UDW Forum June 22 & 23, 2010
Presentation Prepared by Dr. Keith Millheim, Ph.D., Nautilus International LLC Tom Williams, Nautilus International LLC Richard Dessenberger, Knowledge Reservoir Mats Rosengren, Petrodin Project Steering Committee Companies RPSEA Advisory Committee Anadarko Chevron Shell ConocoPhillips Total Project Team Knowledge Reservoir LLC IntecSea Expro University of Tulsa General Marine Contractors Huisman Tidewater GE Baker Hughes Inteq
Outline for Today's Discussion Initial and modified concepts of Project 2501, Technology Assessment Interaction with the project steering committee Play types considered for study Well testing simulation results (to date) Applying simulation results to eight well testing systems o Description of eight well testing systems Future work to accomplish, also considering BP/Horizon impact on deep water well testing
RPSEA UDW Project Goals Meet RPSEA Strategic Theme of Early Appraisal of the Reservoir Reduce the Risk of Uncertainty Provide Pertinent Information It must be Cost Effective
2501 Project Goals 1. Provide a roadmap for well testing options in deep water GOM 2. Evaluate various well testing systems to optimize deep water well testing in the GOM 3. Provide management with a tool to value the application of early well testing on deep water wells 4. Provide engineers and geoscientists with a way to compare various well testing systems for deep water testing applications 5. Provide a practical guide for deep water well testing designs and operations 6. Create computer based spreadsheet for various well testing systems for deep water applications in the GOM focusing on the four major deep water reservoir plays 7. Phase I completed end of 2010
Testing Established as the Industry Norm will be Investigated (1) Early drawdown/build up tests (usually hours to 24 hours) to ascertain average (kh), nearby boundaries (if existing) and distance to the boundaries, skin effects, turbulence factors for gas reservoirs, and initial and/or average reservoir pressures; (2) Medium or longer term testing including a much lower term production schedule followed by longer term build ups. These tests are used to determine potential compartment sizes and a better averaging or variation in kh. (3) The long term production test is a period of production that permits the possible determination of the effects of a contributing aquifer of various sizes, shapes and connectivity. (4) Interference tests between a producer where another well(s) is instrumental to detect any pressure response. This test can detect boundaries, baffles and storage volume between wells (0h)..
Project Update Initial Concept: Refined Concept: Evaluate 4 play types in GoM Walker Ridge Keathley Canyon Alaminos Canyon Eastern Gulf Gas Plays Evaluate 3 play systems (eliminated Eastern Gulf Gas) Middle Miocene (Mad Dog, Atlantis, Neptune, Thunderhorse) Lower Tertiary: Paleocene (Walker Ridge, Keathley Canyon, Jack, St. Malo, Cascade, Chinook, Tucker, etc.) Alaminos Canyon (Perdido) Evaluate Eight well testing systems
Four GoM Deepwater Plays were Previously Identified (RPSEA & Nautilus) Walker Ridge, Keathley Canyon, Alaminos Canyon, Eastern Gulf Gas Plays Green Canyon Mississippi Canyon Atwater Valley Lloyd Ridge Eastern Gas Plays: (Pleistocene thru Jurassic) Alaminos Canyon Keathley Canyon Walker Ridge Lund Henderson
Initial Work Considers only Two Plays Middle Miocene (Mad Dog, Atlantis, Neptune, Thunder Horse, etc.) Lower Tertiary: Paleocene (WR/KC: Jack/St Malo and Cascade/Chinook, Tucker) c
Work Plans Short term, long term, interference test design and nodal analysis were performed for these two types of reservoirs First pass models use a simple, homogeneous, radial model (with the well located in the center of the reservoir) Review preliminary results in conjunction with the RPSEA steering committee and the project team to obtain input on future work
Reservoir Types: Discussion Alaminos Canyon plays (Great White, Trident) to be considered in next phase Shell recently started production from the Perdido Project (OTC 20887 & 20879) Water depth (8,500 ft) is greater than in Walker Ridge fields (7,800 ft) Burial depth is shallower than Walker Ridge fields Oligocene Frio: 10,500 ft TVDss (2,000 ft below the mudline) Eocene Wilcox: 14,000 ft TVDss (5,500 ft below the mudline) Paleocene Wilcox: 19,000 ft TVDss (10,500 ft below the mudline) Walker Ridge fields: ~27,500 ft TVDss (~19,700 ft below mudline) Initial pressure and temperatures (7 9k psia, 150 190F), less than WR plays (19.5k psia, 230F) Would only consider the Eocene and/or Paleocene Wilcox reservoirs Eocene perm is ~100mD, Paleocene is much lower (similar to WR/KC) Reservoir properties are better than WR plays (~35 API, GOR=1500 2500 scf/stb, viscosity= <1 cp) Paleocene GOR is expected to be slightly lower, 500 1000 scf/stb Would not consider the Oligocene Frio (limited number of discoveries) Shallow, heavily faulted, highly compacting reservoirs, contains biodegraded crude (18 API) Would not consider well testing of Eastern Gulf Gas plays Nobody tests for gas, especially not offshore where gas handling can be a problem Gas fields are best co developed as with the Independence Hub development
Middle Miocene Reservoir: Well Test Design and Nodal Analysis
Middle Miocene: Reservoir Parameters First pass simulations use average parameters for Middle Miocene reservoirs Typical ranges for the parameters will need to be identified for sensitivity analysis
Short Term Test Summary Total test duration = 14 hours Total fluid production: Oil = 1,375 stb & Gas = 1.3 MMSCF Maximum pressure drawdown, ΔP = 725 psi Minimum bottom hole flowing pressure is above bubble point pressure (P b = 5,000 psia) Radius of investigation = 960 ft Any boundary within that range will be detected from the well test Rinv will change significantly with a slight change in DD or BU time for Middle Miocene reservoirs Two BU periods are necessary To compare the BU pressure profile (identify any changes in fluid properties) To see if any amount of depletion occurred (compartmentalization) To run independent PT analysis to identify any changes in reservoir properties (change in permeability or skin)
Long Term Well Test Objectives Prove up the drainage area of a well Estimate duration of test and rate required to: See reservoir boundaries, or Achieve a radius of investigation large enough to prove up the drainage area for the well Estimate duration of test required to identify pressure depletion within assumed drainage area Assumptions Reservoir size is assumed and boundary distance is estimated accordingly Test duration will make sure to identify the boundary and pressure depletion First pass model will use average parameters Pressure drawdown should not exceed the bubble point pressure at the sandface
Long Term Test Summary Total test duration = 28 days for an OOIP = 17 MMSTB Total fluid production: Oil = 129 MBO & Gas = 129 MMSCF Maximum pressure drawdown, ΔP = 829 psi Minimum bottom hole flowing pressure is above bubble point pressure (P b = 5,000 psia) Pressure depletion during the test = 330 psi Average flow rate during the test = 6,000 stb/day The log log plot based on the simulated pressure data shows a boundary effect after 10 days of DD/BU
Interference Test: Production Rate Schedule for Active Well PERIOD DURATION CUMULATIVE DURATION OIL RATE CUMULATIVE OIL (DAYS) (DAYS) (STB/D) (STB) Production #1 2 2 2000 4000 Shut in #1 2 4 0 4000 Production #2 7 11 4000 32000 Shut in #2 21 32 0 32000 The test design consists of two wells 1,500 ft apart Active well produces as specified The pressure is monitored in the observation well (downhole). The observation well does not produce during the test.
Overall Summary: Middle Miocene Short term test Long term test Total duration of test, days 0.5 28 Total fluid production, MBO 1.3 129 Approximate pressure DD, psi 725 825 Radius of investigation, ft 900 2730
Lower Tertiary Reservoir: Well Test Design and Nodal Analysis
Short and Long Term Test Design Objectives Determine the test duration and rate required to obtain radial flow Long term test: to see boundary or achieve a radius of investigation large enough to prove up the drainage area of the well Identify test duration required to estimate pressure depletion within drainage area Use the results as input to a nodal analysis (using Prosper) to calculate temperature and pressures downhole, at the mudline, and at the separator Challenges Limited data are available for Lower Tertiary reservoirs Low permeability rock, compared to Middle Miocene (perm = 5 to 30 md) High fluid viscosity (viscosity = 3 to 10 cp) High pressure drawdown during the test (limited PI) Reservoir size for Lower Tertiary reservoirs is unknown
Lower Tertiary (Paleogene): Reservoir Parameters Initial simulations will focus on typical parameters for Lower Tertiary reservoirs Oligocene and Eocene (Frio and Upper Wilcox) plays in Alaminos Canyon are not included Typical ranges for the parameters will need to be identified for sensitivity analysis
Short term Test Summary (LT GOM) Total test duration = 24 hours Total fluid production = 895 STB oil and 0.25 MMSCF gas (GOR = 300 scf/stb) Radius of investigation is expected to be ~140 ft (Rinv for middle Miocene = 960 ft@ 6 hours) Maximum pressure drawdown ΔP = 6,000 psia with flow rate = 3,000 stb/d (for Middle Miocene, ΔP = 725 psi with flow rate = 6,000 stb/d) BHP = 13,500 psia, which is above the bubble point pressure (P b = 1,200 psia) Productivity Index is very low, PI = 0.5 bbl/psia
Long term Test Summary (LT GOM) Low permeability rock and high fluid viscosity result in a small radius of investigation A long DD/BU duration is required to detect boundaries and generate a measurable amount of depletion The test starts with a relatively low rate for a short period and a quick BU This is to make sure that all tools are working as expected The collected data can be used to estimate initial reservoir pressure Maximum pressure drawdown is ~6,100 psia, which is well above the bubble point (P b = 1,200 psia). Flow rate limit = 2,500 stb/d used to minimize the drawdown pressure (low PI) Total fluid production: Case I (OOIP= 10 MMSTB) Case II (OOIP= 30 MMSTB) Case III (OOIP= 70 MMSTB) Oil production (MBO) Gas production (MMCF) 46.5 86 173.5 14 26 52 Duration (days) 37 69 137
Interference Test Summary (LT GOM) Duration of interference test varies from 2 months to 10 years for well distances of 150 to 1000 ft For Middle Miocene reservoirs, the test duration is only 1 month for well distances of 1,500 ft Production rate is high to create more pressure drawdown Pressure drawdown at observant well is approximately 2,000 psi for a flow rate of 5,000 stb/d with a well separation of 250 ft For the rate of 2,500 stb/d, pressure drawdown after 180 days is only ~900 psi Interference testing between vertical wells is not very practical for Lower Tertiary reservoirs (based on typical rock and fluid properties)
Eight Well Testing Systems
Three Well Testing Systems have Drilling Riser, No Subsea Tree Five Well Testing Systems have Surface Vessel, Subsea Production Tree
System 1 Standard deep water MODU, drilling riser, subsea BOPs, production facilities and oil storage on the MODU (usually used for short term tests). System 1 Components MODU Produce into drillship Conventional Riser (Drill Pipe/ Tubing) Subsea BOPs Pros Requires only a single vessel Uses very standard equipment Cons Expensive to rent MODU Limited number of MODU drill ships with crude storage capacity High Risk!
System 2 Standard deep water MODU, drilling riser, surface BOPs, production facilities and oil storage on the MODU Pros Lower cost for surface BOP than subsea Faster to set up casing riser with surface BOP than marine riser with subsea BOP Cons Still requires a MODU (expensive) Requires a high pressure riser High Risk!
System 3 Standard deep water MODU, drilling riser, surface BOPs, production facilities and oil storage on the MODU. Pros Proven concept for DST/EWT in GOM Cons Added difficulty of mooring MODU to FPSO or FSO/FPU Environmental limitations Same as System 1 and 2 but produce/store in other vessels FPU or FPSO
System 4 Seillean system where the vessel has the ability to run a production riser, connect and disconnect to subsea production tree, treat the produced fluids and store the oil or transfer the oil to another storage vessel. Pros Emergency Disconnect System installed on top of the tree FPSO with self contained riser handling system Cons Currently used with a single barrier riser Seillean type vessels are expensive Seillean Method Drill Pipe Tree
System 5 This testing system connects the production tree via flexible pipe to a vessel that processes the fluids and either stores the fluids or transfers the fluids to another storage vessel, requires some type of intervention vessel to run and retrieve the flexible line, and to do any intervention done to the well by a MODU or intervention type vessel. Assumes all controlling of the subsea tree is from the primary production vessel. Pros Low cost compared to Systems 1 4 FPSO with self contained riser handling system Cons Lesser operational capacity than Systems 1 4 due to size of vessel Jack Test
System 6 This system uses an intervention vessel or MODU to connect to the subsea production tree via a production riser where the intervention vessel or MODU can intervene through the production tree to the well, i.e., re complete, pull tubing, run special down hole equipment. The intervention vessel or MODU remains during the entire testing sequence. The production is transferred to a FPU/storage vessel or an FPSO.
System 7 This testing system uses a self standing riser (SSR) that connects to production tree and produces either through the riser (single barrier) or through a tie back liner in the riser (double barrier). The SSR is either installed by an intervention vessel or special designed vessel to run the riser. Any MODU or intervention vessel can intervene through the production tree to the well. Production goes to an FPU/storage vessel or an FPSO. PRO: The system can be conducted absent a MODU PRO: Has advantages for mobilization time during hurricanes PRO: Low cost riser solution PRO: Can be used with single or dual barrier risers CON: DP moored vessel; Depending on the riser solution from the tree (on top of the buoyancy element) a limited DP watch circle (allowed vessel positioning excursion) may be required if the jumper is short. Develop a riser swivel arrangement (outrigger)
System 8 Underwater SSRs Consists of SSR connected to sea floor with a suction anchor. Only used when subsea production tree will not support an SSR. Any work on the well must be done by an intervention vessel or MODU. Used to Support Production Lines
Future Tasks Middle Miocene Lower Tertiary Computer Based Spreadsheet for Deep Water GOM Applications
Middle Miocene Short term and long term well test design Low/variable rates to see if the test objectives can be met using lower rates Create an injection case Change from downhole shut in the surface shut in to assess impact on test design Assess the impact of aquifer on test design ( assume a weak aquifer) Nodal analysis Perform a nodal analysis for an injection test Assess impact of a more realistic inlet separator pressure (~1,000 psi) Interference test Examine use of a shorter production test (short pulse test design) Use a well spacing of 4000 ft, and a permeability of 500 md case Assess if an interference test could be used instead of a long term production test
Lower Tertiary Short term and long term test design Model a case assuming the well is hydraulically fractured Create an injection case Change from downhole shut in the surface shut in to assess impact on test design Run sensitivities on oil viscosity and permeability Oil viscosity (3 10 cp) Permeability (5 30md) Correlate between mobility and test duration. Model a horizontal well case, including a sensitivity on kv/kh Use RF=10% Nodal analysis Perform a nodal analysis for an injection test Assess impact of a more realistic inlet separator pressure (~1,000 psi) Interference test Examine use of a shorter production test (short pulse test design) Assess if an interference test could be used instead of a long term production test Perform short term, long term, nodal analysis and interference test for test for an Eocene Upper Wilcox reservoir (Perdido type reservoir)
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