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Crosshole EM for oil field characterization and EOR monitoring: Field examples

Description: Crosshole and surface-to-borehole electromagnetic (EM) imaging is applied to reservoir characterization and steam flood monitoring in a central California oil field. Steam was injected into three stacked, eastward-dipping, unconsolidated oil sands within the upper 200 in. The steam plume is expected to develop as an ellipse aligned with the regional northwest-southeast strike. EM measurements were made from two flberglass-cased observation wells straddling the steam injector on a northeast-southwest profile. Field data were collected before the initiation of a steam drive to map the distribution of the oil sands and then six months after the steam was injected to monitor the progress of the steam chest. Resisitivity images derived from the EM data collected before steam injection clearly delineate the distribution and dipping structure on the target oil sands. Difference images from data collected before and after steam flooding indicate that the steam chest has developed only in the deeper oil sands, and it has preferentially migrated eastward. Surface-to-borehole measurements were useful in mapping the distribution of the major oil sands, but they were insensitive to resisitivity changes in the early stages of the steam flood.
Date: September 1, 1994
Creator: Wilt, M.; Schenkel, C.; Torres-Verdin, C.; Lee, Ki Ha & Tseng, Hung-Wen
Partner: UNT Libraries Government Documents Department

Measurement of Downhole Steam Quality and Total Energy by Optical Methods

Description: Initial steps have been taken to measure the mass of water in vapor and liquid phases downhole in a steam injection heavy oil recovery system. A suitable portion of the electromagnetic spectrum has been identified over which the presence of liquid water and vapor can be separated. This is in the near infrared and extends from ~900 nm to 1.8 ┬Ám region. A high pressure and high temperature cell has been constructed and tested for stagnant transmissions. Pitting of the optical ports due to the presence of high-pressure (8.5 MPA) and high temperature (300C) water has lead to a redesign of the optical ports, these modifications will be incorporated in the next quarter. The actual determination of the mass of water, either in liquid or vapor, has not been reliably determined, due in part to the pitting problems being addressed in the modification. However, qualitative data has been recorded clearly showing an increase in absorption with increasing number of absorbing molecules, i.e. mass of water.
Date: April 1, 1998
Creator: Donaldson, A. B. & Allen, Graham R.
Partner: UNT Libraries Government Documents Department

Porosity and Permeability Evolution Accompanying Hot fluid Injection into Diatomite, SUPRI TR-123

Description: An experimental study of silica dissolution was performed to probe the evolution of permeability and porosity in siliceous diatomite during hot fluid injection such as water or steam flooding. Two competing mechanisms were identified. Silica solubility in water at elevated temperature causes rock dissolution thereby increasing permeability; however, the rock is mechanically weak leading to compressing of the solid matrix during injection. Permeability and porosity can decrease at the onset of fluid flow. A laboratory flow apparatus was designed and built to examine these processes in diatomite core samples.
Date: April 19, 2001
Creator: Diabira, I.; Castanier, L.M. & Kovscek, A.R.
Partner: UNT Libraries Government Documents Department

Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

Description: The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.
Date: November 20, 2002
Creator: Gabitto, Jorge & Barrufet, Maria
Partner: UNT Libraries Government Documents Department

Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

Description: The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.
Date: November 20, 2002
Creator: Gabitto, Jorge & Barufet, Maria
Partner: UNT Libraries Government Documents Department

A Numerical Analysis of the Single-Well Steam Assisted Gravity Drainage (SW-SAGD) Process, SUPRI TR-124

Description: Results from this study include cumulative recoveries, temperature distributions, and production rates. It was found that cyclic steaming of the reservoir offers the most favorable option for heating the near-wellbore area to create conditions that improve initial SAGD response. More favorable reservoir conditions such as low viscosity, thick oil zones, and solution gas, improved reservoir response. Under unfavorable conditions, response was limited.
Date: July 23, 2001
Creator: Elliot, K.T. & Kovscek, A.R.
Partner: UNT Libraries Government Documents Department

Reactivation of an Idle Lease to Increase Heavy Oil Recovery through Application of Conventional Steam Drive Technology in a Low-Dip Slope and Reservoir in the Midway-Sunset Field, San Jaoquin Basin, California, Class III

Description: The objective of the project is not just to commercially produce oil from the Pru Fee property, but rather to test which operational strategies best optimize total oil recovery at economically acceptable rates of production volumes and costs.
Date: February 21, 2002
Creator: Schamel, Steven; Deo, Milind & Deets, Mike
Partner: UNT Libraries Government Documents Department

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes

Description: The emphasis of this work was on investigating the mechanisms and factors that control the recovery of heavy oil with the objective to improve recovery efficiencies. For this purpose the interaction of flow transport and reaction at various scales from the pore network to the field scales were studied. Particular mechanisms to be investigated included the onset of gas flow in foamy oil production and in in-situ steam drive, gravity drainage in steam processes, the development of sustained combustion fronts and the propagation of foams in porous media. Analytical, computational and experimental methods were utilized to advance the state of the art in heavy oil recovery. Successful completion of this research was expected to lead to improvements in the Recovery efficiency of various heavy oil processes.
Date: March 11, 2002
Creator: Yorstos, Yanis C.
Partner: UNT Libraries Government Documents Department

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes

Description: This project is an investigation of various multi-phase and multiscale transport and reaction processes associated with heavy oil recovery. The thrust areas of the project include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.
Date: August 7, 2001
Creator: Yortsos, Yanis C.
Partner: UNT Libraries Government Documents Department

An Analytical Model for Simulating Heavy-Oil Recovery by Cyclic Steam Injection Using Horizontal Wells, SUPRI TR-118

Description: In this investigation, existing analytical models for cyclic steam injection and oil recovery are reviewed and a new model is proposed that is applicable to horizontal wells. A new flow equation is developed for oil production during cyclic steaming of horizontal wells. The model accounts for the gravity-drainage of oil along the steam-oil interface and through the steam zone. Oil viscosity, effective permeability, geometry of the heated zone, porosity, mobile oil saturation, and thermal diffusivity of the reservoir influence the flow rate of oil in the model. The change in reservoir temperature with time is also modeled, and it results in the expected decline in oil production rate during the production cycle as the reservoir cools. Wherever appropriate, correlations and incorporated to minimize data requirements. A limited comparison to numerical simulation results agrees well, indicating that essential physics are successfully captured. Cyclic steaming appears to be a systematic met hod for heating a cold reservoir provided that a relatively uniform distribution of steam is obtained along the horizontal well during injection. A sensitivity analysis shows that the process is robust over the range of expected physical parameters.
Date: August 9, 1999
Creator: Diwan, Utpal & Kovscek, Anthony R.
Partner: UNT Libraries Government Documents Department

Computer Simulation of Single-Well Steam Assisted Gravity Drainage (SW-SAGD), SUPRI TR-119

Description: Steam assisted gravity drainage (SAGD) is an effective method of producing heavy oil and bitumen. In a typical SAGD approach, steam is injected into a horizontal well located directly above a horizontal producer. A steam chamber grows around the injection well and helps displace heated oil toward the production well. Single-well (SW) SAGD attempts to create a similar process using only one horizontal well. This may include steam injection from the toe of the horizontal well with production at the heel. Obvious advantages of SW-SAGD include cost savings and utility in relatively thin reservoirs. However, the process is technically challenging. To improve early-time response of SW-SAGD, it is necessary to heat the near-wellbore area to reduce oil viscosity and allow gravity drainage to take place. Ideally heating should occur with minimal circulation or bypassing of stream. Since project economics are sensitive to early production response, we are interested in optimizing the start -up procedure.
Date: August 9, 1999
Creator: Elliott, Keith T. & Kovscek, Anthony R.
Partner: UNT Libraries Government Documents Department

Electromagnetic Heating Methods for Heavy Oil Reservoirs

Description: The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.
Date: May 1, 2000
Creator: Sahni, A.; Kumar, M. & Knapp, R.B.
Partner: UNT Libraries Government Documents Department

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes

Description: This report is an investigation of various multi-phase and multiscale transport and reaction processes associated with heavy oil recovery. The thrust areas of the project include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.
Date: May 29, 2001
Creator: Yortsos, Y. C.
Partner: UNT Libraries Government Documents Department

Investigation of Multiscale and Multiphase Flow, Transport and Reaction in Heavy Oil Recovery Processes

Description: In this report, the thrust areas include the following: Internal drives, vapor-liquid flows, combustion and reaction processes, fluid displacements and the effect of instabilities and heterogeneities and the flow of fluids with yield stress. These find respective applications in foamy oils, the evolution of dissolved gas, internal steam drives, the mechanics of concurrent and countercurrent vapor-liquid flows, associated with thermal methods and steam injection, such as SAGD, the in-situ combustion, the upscaling of displacements in heterogeneous media and the flow of foams, Bingham plastics and heavy oils in porous media and the development of wormholes during cold production.
Date: October 8, 2002
Creator: Yortsos, Yanis C.
Partner: UNT Libraries Government Documents Department

Method for cutting steam heat losses during cyclic steam injection of wells. Final report

Description: Heavy Oil is abundant in California. It is a very viscous fluid, which must be thinned in order to flow from wells at economical rates. The best method of oil viscosity reduction is by cyclic steam injection into the oil-containing rock formations. Making steam in conventional generators fueled with Natural Gas is, however, a costly process. The main objective of this Project is to reduce the cost of the required steam, per Barrel of Oil produced. This is made possible by a combination of Patented new technologies with several known methods. The best known method for increasing the production rate from oil wells is to use horizontal drainholes, which provide a much greater flow area from the oil zone into the well. A recent statistic based on 344 horizontal wells in 21 Canadian Oil fields containing Heavy Oil shows that these are, on the average six times more prolific than vertical wells. The cost of horizontal wells, however, is generally two to three times that of a vertical well, in the same field, so our second goal is to reduce the net cost of horizontal wells by connecting two of them to the same vertical casing, well head and pumping system. With such a well configuration, it is possible to get two horizontal wells for the price of about one and a half times the price of a single vertical well.
Date: December 1, 1995
Creator: Gondouin, M.
Partner: UNT Libraries Government Documents Department

Method for cutting steam heat losses during cyclic steam injection of wells. Fourth quarterly report

Description: Effective Gravel-packing of horizontal wells is difficult to achieve, using conventional pre-slotted liners, yet it is generally required in the soft Heavy Oil reservoir rocks of California, where cyclic steam injection has been proven to be the most cost-effective oil recovery method. The proposed method of gravel placement behind a non-perforated liner, which is later perforated {open_quotes}in situ{close_quotes} with a new tool operated by coiled-tubing, is expected to greatly reduce costs resulting from sand production in horizontal wells operated under cyclic steam injection. The detailed configuration of the prototype tool is described. It includes two pairs of cutting wheels at the ends of spring-loaded pivoting arms, which are periodically pressed through the liner wall and shortly thereafter retracted, while the coiled tubing is being pulled-out. For each operating cycle of the hydraulically-operated tool, this results in a set of four narrow slots parallel to the liner axis, in two perpendicular diametral planes. The shape of the edges of each slot facilitates bridging by the gravel particles, for a more effective and compacted gravel-packing. The tool includes a few easily-assembled parts machined from surface-hardened alloy steel presenting great toughness, selected from those used in die making. The operation of the system and potential future improvements are outlined. The method of fabrication, detailed drawings and specifications are given. They will serve as a basis for negotiating subcontracts with qualified machine shops.
Date: February 1, 1995
Partner: UNT Libraries Government Documents Department

Method for cutting steam heat losses during cyclic steam injection of wells. Sixth quarterly report

Description: Slot-cutting tests were made in a 3.5 in. OD steel pipe representative of the proposed liner of the twin gravel-packed horizontal drainholes used in this Method, for the following purposes: (1)To determine the force required to punch through the liner wall in order to achieve its full penetration with a cutting wheel, (2)To select the most effective profile for the cutting wheel. The results of these tests, made at UC-Berkeley indicated that, with four cutting wheels, as included in the tool design presented in the Fourth Quarterly Report, the total force required was nearly 60,000 lb. In view of the limited tool diameter, the creation of such a large force with a single piston required a hydraulic pressure which would exceed the capability of the Triplex pump, most commonly available in the oil fields. A re-design of the 4-wheel slot-cutting tool with two tandem pistons was done, but revealed a high degree of complexity, related to the difficulty of providing a high-pressure fluid path in the thin housing wall from the hydraulic cylinder above the first pair of arms to a cylinder for the tandem piston located below the first pair of cutter arms and operating the second pair of arms. By reducing the number of cutting wheels from 4 to 3 a single piston driver was sufficient and could result in a tool much simpler to build and to maintain in the Field.The re-designed 3-wheel slot-cutting tool is presented here. It is currently under construction at UC-Berkeley. A second test program will follow, when this simplified modular tool has been assembled. The objective of this second series of tests is to determine the required characteristics of the opposing spring, or Belleville rings stack which, in the new design, is used for retraction of the cutters, rather than for their ...
Date: August 1, 1995
Partner: UNT Libraries Government Documents Department

Reactivation of an idle lease to increase heavy oil recovery through application of conventional steam drive technology in a low dip slope and basin reservoir in the Midway-Sunset Field, San Jaoquin Basin, California

Description: This project reactivates ARCO`s idle Pru Fee lease in the Midway- Sunset field, California and conducts a continuous steamflood enhanced oil recovery demonstration aided by an integration of modern reservoir characterization and simulation methods. Cyclic steaming is being used to reestablish baseline production within the reservoir characterization phase of the project. During the demonstration phase scheduled to begin in January 1997, a continuous steamflood enhanced oil recovery will be initiated to test the incremental value of this method as an alternative to cyclic steaming. Other economically marginal Class III reservoirs having similar producibility problems will benefit from insight gained in this project. The objectives of the project are: (1) to return the shut-in portion of the reservoir to optimal commercial production; (2) to accurately describe the reservoir and recovery process; and (3) to convey the details of this activity to the domestic petroleum industry, especially to other producers in California, through an aggressive technology transfer program. One of the main objectives of Budget Period I was to return the Pru Fee property to economic production and establish a baseline productivity with cyclic steaming. By the end of the second quarter 1996, all Pru producers except well 101 had been cyclic steamed two times. Each steam cycle was around 10,000 barrels of steam (BS) per well. No mechanical problems were found in the existing old wellbores. Conclusion is after several years of being shut-in, the existing producers on the Pru lease are in reasonable mechanical condition, and can therefore be utilized as viable producers in whatever development plan we determine is optimum. Production response to cyclic steam is very encouraging in the new producer, however productivity in the old producers appears to be limited in comparison.
Date: November 1, 1996
Creator: Schamel, S.
Partner: UNT Libraries Government Documents Department

Increasing heavy oil reserves in the Wilmington oil field through advanced reservoir characterization and thermal production technologies. [Quarterly report], October 1, 1995--December 31, 1995

Description: The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., California using advanced reservoir characterization and thermal production technologies. This is the third quarterly technical progress report for the project. Through December 1995, the project is on schedule and on budget. Several significant technical achievements have already been successfully accomplished including the drilling of four horizontal wells (two producers and two steam injectors) utilizing a new and lower cost drilling program, the drilling of five observation wells to monitor the horizontal steamflood pilot, the installation of a subsurface harbor channel crossing for delivering steam to an island location, and a geochemical study of the scale minerals being created in the wellbore. Steam injection into the two horizontal injection wells began in mid-December 1995 utilizing the new 2400 ft steam line under the Cerritos Channel. Work on the basic reservoir engineering is expected to be completed in March 1996. A working deterministic geologic model was completed which allowed work to commence on the stochastic geologic and reservoir simulation models.
Date: January 31, 1996
Creator: Hara, S.
Partner: UNT Libraries Government Documents Department

A Comparison of Mass Rate and Steam Quality Reductions to Optimize Steamflood Performance

Description: Many operators of steamdrive projects will reduce the heat injection rate as the project matures. The major benefit of this practice is to reduce the fuel costs and thus extend the economic life of the project. However, there is little industry consensus on whether the heat cuts should take the form of: (1) mass rate reductions while maintaining the same high steam quality, or (2) steam quality decreases while keeping the same mass rate. Through the use of a commercial three-phase, three-dimensional simulator, the oil recovery schedules obtained when reducing the injected steam mass rate or quality with time were compared under a variety of reservoir and operating conditions. The simulator input was validated for Kern River Field conditions by using the guidelines developed by Johnson, et at. (1989) for four steamflood projects in Kern River. The results indicate that for equivalent heat injection rates, decreasing the steam injection mass rate at a constant high quality will yield more economic oil than reducing the steam quality at a constant mass rate. This conclusion is confirmed by a sensitivity analysis which demonstrates the importance of the gravity drainage/steam zone expansion mechanism in a low-pressure, heavy oil steamflood with gravity segregation. Furthermore, the impact of discontinuous silts and nonuniform initial temperatures within the steamflood zone was studied, indicating again that a decreasing mass rate injection strategy is a superior operating practice.
Date: August 9, 1999
Creator: Messner, Gregory L.
Partner: UNT Libraries Government Documents Department

Research on oil recovery mechanisms in heavy oil reservoirs. [Quarterly] report, April--June 30, 1995

Description: The goal of the Stanford University Petroleum Research Institute is to conduct research directed toward increasing the recovery of heavy oils. Presently, SUPRI is working in five main directions: (1) Flow properties studies -- To assess the influence of different reservoir conditions (temperature and pressure) on the absolute and relative permeability to oil and water and on capillary pressure. (2) In-situ combustion -- To evaluate the effect of different reservoir parameters on the in-situ combustion process. Ibis project includes the study of the kinetics of the reactions. (3) Steam with additives - To develop and understand the mechanisms of the process using commercially available surfactants for reduction of gravity override and channeling of steam. (4) Formation evaluation -- To develop and improve techniques of formation evaluation such as tracer tests and pressure transient tests. (5) Field support services -- To provide technical support for design and monitoring of DOE sponsored or industry initiated field projects. Accomplishments for this quarter are briefly described for each study.
Date: September 1, 1995
Creator: Brigham, W.E.
Partner: UNT Libraries Government Documents Department

Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

Description: The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibria, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.
Date: December 18, 2001
Creator: Gabitto, Jorge & Barrufet, Maria
Partner: UNT Libraries Government Documents Department

Modification of chemical and physical factors in steamflood to increase heavy oil recovery

Description: This report covers the work performed in the various physicochemical factors for the improvement of oil recovery efficiency. In this context the following general areas were studied: (1) The understanding of vapor-liquid flows in porous media, including processes in steam injection; (2) The effect of reservoir heterogeneity in a variety of foams, from pore scale to macroscopic scale; (3) The flow properties of additives for improvement of recovery efficiency, particularly foams and other non-Newtonian fluids; and (4) The development of optimization methods to maximize various measures of oil recovery.
Date: January 19, 2000
Creator: Yortsos, Yanis C.
Partner: UNT Libraries Government Documents Department