Enhanced Recovery

   Enhanced Recovery

Enhanced Recovery

MHA has significant domestic U.S. and international experience evaluating enhanced recovery projects, including waterflooding, CO2 injection, miscible flooding, and thermal recovery projects. MHA builds numerical simulation models that are calibrated to reservoir performance and used to optimize and predict recovery from these types of projects. In some cases these projects have also involved the creation of detailed static geologic models of the subsurface geology.

The following are a few examples of MHA experience in the evaluation of thermal recovery projects:

Cedar Hills, North Dakota
The Cedar Hills South field located in the southwest corner of North Dakota is one of the the largest onshore oil fields discovered in the lower 48 portion of the United States. The successful development of this low permeability oil field reflects the ability of horizontal wells to more efficiently deplete the oil productive flank of the Cedar Creek Anticline than could be achieved using vertical wells completed in the carbonate Ordovician Red River B formation. MHA was contracted to investigate the optimum method of depletion with the possible choices being primary depletion, waterflooding or enhanced recovery via high pressure air injection (HPAI). In addition, MHA was also responsible for preparing the technical submittals and technical presentation before the North Dakota Oil Conservation Commission.

MHA developed a geological model that incorporated the critical parameters required to accurately predict historical and future performance of the field. This geological model was input into both conceptual and full field simulation models. The conceptual models were used to define the expected behavior of different depletion approaches while the full field models were used to define the behavior of specific parts of each field and to define appropriate equity splits for unitization of the field. The history matched full field models were used to determine the ultimate recovery for primary recovery, waterflooding, waterflooding with infill drilling and for HPAI. The full field model was also used as input to determine the feasibility of CO2 flooding. As a result of these studies, waterflooding combined with infill drilling was selected as the development plan for the field. Production was subsequently increased from 3,000 BOPD to a peak waterflood rate in excess of 40,000 BOPD.

Riley Ridge Field Evaluation and Legal Testimony
MHA recently conducted a detailed engineering and compositional reservoir simulation investigation into the injection of CO2 into the Riley Ridge Field located in Wyoming. MHA constructed a detailed 3D geological model characterizing the complex and heterogeneous geology of the field. MHA then history matched the existing pressure and production data from the field and generated predictions of reservoir behavior under future CO2 injection.

The results of the MHA evaluation were the foundation of testimony in a legal arbitration with held before the Wyoming Oil and Gas Conservation Commission. The Wyoming Commission ruled in favor, and the project has moved forward with the development and injection plans for the field.

Ashtart Field CO2 Feasibility Study
MHA conducted engineering and reservoir simulation studies to evaluate the feasibility of CO2 flooding the Ashtart oilfield located offshore Tunisia. The Ashtart field was discovered in 1972. A total of 45 wells have been drilled in the field to date, with 24 production wells and 6 water injection wells currently on line. Estimated recoverable reserves are 5.2 million tons of oil.

MHA initially designed and evaluated the laboratory PVT and EOR studies to properly characterize the reservoir fluids, the anticipated miscibility pressures, and the residual saturations following the flooding. Simulation sensitivity studies were then conducted on numerous sector models throughout the field to evaluate the response to injection of pure CO2, as well as a gas mixture of 75% CO2 and 25% methane. Fully compositional simulation models were used for the investigation. The use of sector models helped to quantify the range of results and well requirements given significant variations in reservoir characteristics and reservoir heterogeneity. Full field modeling was then undertaken to develop production profiles, identify well and facility requirements, and to conduct detailed economic evaluation of the benefits of CO2 flooding the Ashtart field.

Salt Creek Light Oil Unit CO2 Feasibility Study
MHA evaluated the feasibility of CO2 flooding the Salt Creek field located in Natrona County, Wyoming. The Salt Creek Light Oil Unit (Second Wall Creek formation) contained over 700 MMSTB of original-oil-in-place and has been extensively water flooded for over 40 years. MHA evaluated various aspects of a commercial demonstration project including performance under both immiscible and miscible CO2 injection and various operating strategies to optimize field facility requirements.

Round Mountain Field, California
Conducted a thermal simulation model study of a large steamflood project for the Vedder sand in this field. The field is highly faulted and there is a down dip active aquifer. The model contained over 200 active wells. Determined the optimum plan for future development wells and steam injection rates. Investigated various development strategies and reservoir management schemes to achieve the highest and most efficient oil recovery.

Poso Creek Field, California
Performed a steamflood simulation study of the Basal Etchegoin sands on a 160 acre lease in the Poso Creek oil field. The purpose of this simulation study was to investigate an old steamflood through a history match of production to date, and then to perform a parametric prediction study to determine how the steamflood could have been made more effective. The results of the study were used to design a grassroots steamflood project for a neighboring lease using a combination of horizontal and vertical wells.

Lynch Canyon Field, California
Built a thermal simulation model of a small heavy oil field (10 degrees API gravity crude oil). The field had been developed in the mid-2000’s with both horizontal and vertical wells. Over 90 steam cycles have been performed in the Monterey formation prior to the study. The purpose of the study was to determine a preferred strategy for conversion from steam cycling to steamflood and to select the optimum steam injection rates for each strategy.

Midway Sunset Field, California
Conducted a reservoir simulation study of the Marvic, Potter and Tulare reservoirs in the northern area of this giant oil field. There were about 650 wells with heavy oil production in the study area. The purpose of this thermal simulation study was to investigate operating policies (cyclic steam vs. steam drive) and well configuration and pattern sizes for the three reservoirs. The study helped the client identify the best operational strategy for its limited steam generation capacity and predict future oil recovery for a variety of going forward development scenarios.

North Buzachi Field, Mangyshlak Oblast, Kazakhstan
MHA staff prepared a development feasibility study for this field located on the northwestern part of the Buzachi peninsula near the Caspian Sea. A joint venture with selected foreign companies was proposing to use advanced western technology and equipment to commercially develop the heavy oil resources in the field. Objectives included reserves review, screening of reservoirs for thermal recovery, audit of proposed development plans, assessment of the likelihood of recovering the assigned oil volumes, and recommendations for drilling locations and well spacing requirements.

Reserves Reporting, Various Companies
Evaluated and estimated proved and unproved reserves for leases undergoing thermal recovery operations in heavy oil fields located in the San Joaquin Valley, California. Reserves were based on Society of Petroleum Engineers guidelines. The properties were located in areas of active steam injection projects for the Midway Sunset, Poso Creek, Edison and Belridge oil fields.