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Abstract Development of marginal/mature fields has become popular because of a significant decline in new field discoveries and high oil prices. In particular, small size fields of this kind are more challenging because of limited options for development. This paper presents a study on the Sinclair field located in Alberta, Canada. The field has 19 wells, six of which are horizontal, and have been in production for more than 20 years. Despite the quality of oil (40°API, 1.5 cp) and rock properties (20% average porosity, water-wet sandstone), the current production is less than 100 bbl/D for the whole field. The field is now undergoing waterflooding. The main challenges are the thin pay zone (~4 m), severe water production and a puzzling recovery factor of approximately 10%. The current study consists of three phases: numerical reservoir modelling and history match to understand the reasons for low oil production and to analyze the hydrodynamic characteristics of the field, characterization of reservoir and interwell connectivity using static and production data and proposing an enhanced oil recovery technique supported by field scale numerical simulation. After modelling and history matching stages, potential reserves locations are estimated for possible dilute surfactant injection. Based on interwell connectivity, different injection schemes that use some producers as injectors are tested. The obtained results are subject to further evaluation and analysis to derive the economic viability of the field.
- North America > Canada > Alberta > Saddle Hills County (0.62)
- North America > Canada > Alberta > Grande Prairie County No. 1 (0.62)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.49)
- Geology > Geological Subdiscipline (0.48)
Abstract CO2 flooding in naturally fractured reservoirs is becoming increasingly more popular. The Midale Field is a good example of this phenomenon and has gained a great deal of interest, not only from enhanced oil recovery, but also from a CO2 sequestration point of view. To consider future opportunities for greenhouse sequestration in these types of reservoirs while improving oil recovery specifically in the Midale field, a series of experiments were performed. The goal of this work was to study the effect of miscibility (miscible, immiscible and near-miscible regions) and injection rate on incremental oil recovery and sequestration during continuous injection in fractured porous media. Another important aspect considered was to analyze the effect of pressure drawdown or depletion on additional recovery with sequestration optimization. First, artificially fractured Berea sandstone samples were used. CO2 was injected at constant, slow rates into the fracture, while maintaining the high-pressure into the core and the system. At the end of the production life, the pressure into the system was released to different pressure steps and kept for a longer period of time at each of the reduced steps of pressure. In between two pressure steps, the system was shut down for enough time to observe the effect of CO2 and oil diffusion/back diffusion. After a series of Berea sandstone experiments, a few tests were conducted on the Midale cores, which were obtained from a good quality matrix part of the field. Injection and production data were collected using a continuous data logging system, an analysis of the produced liquids and measuring the gas production using a continuous flowmeter, which led to the understanding of the mechanism. The results showed that the pressure blowdown, followed by shut in after continuous injection, can increase oil recovery significantly until a certain critical pressure. Storage capacity of the rock with change in pressure and amount of oil recovered during blowdown period will lead to the critical understanding of abandonment pressure during the project life to achieve the goal of sequestration and recovery optimization.
- North America > Canada > Saskatchewan (0.54)
- North America > United States > West Virginia (0.47)
- North America > United States > Pennsylvania (0.47)
- (2 more...)
- Research Report > New Finding (0.68)
- Research Report > Experimental Study (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.48)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.46)
- North America > Canada > Saskatchewan > Williston Basin > Midale Field > Midale Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Midale Field > Charles Formation (0.99)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Miscible methods (1.00)
- (2 more...)
This paper was prepared for the 2009 SPE/EAGE Reservoir Characterization and Simulation Conference. Abstract Well log and core information, seismic surveys, outcrop studies, and pressure transient tests are usually insufficient to generate representative 3-D fracture network maps individually. Any combination of these sources of data could potentially be used for accurate preparation of static models. Our previous attempts showed that there exists a strong correlation between the statistical and fractal parameters of 2-D fracture networks and their permeability (Jafari and Babadagli, 2009). We extend this work to fracture network permeability estimation using the statistical and fractal properties data conditioned to well test information. For this purpose, 3-D fracture models of nineteen natural fracture patterns with all known fracture network parameters were generated initially. It is assumed that 2-D fracture traces on the top of these models and also 1-D data from imaginary wells which penetrated the whole thickness of the cubic models were available, as well as pressure transient tests of different kinds. The 1- and 2-D data include statistical parameters (density and length distribution) and ten different fractal characteristics of different properties of the fracture system. Next, the permeability of each 3-D fracture network model was calculated and then converted into a grid based permeability map for drawdown well test simulations using commercial software packages. Finally, an extensive multivariable regression analysis using the statistical and fractal properties and well test permeability as independent variables was performed to obtain a correlation for equivalent fracture network permeability. The equation was validated against different natural and synthetic fracture network patterns. The cases requiring expensive well (logsand cores) and reservoir (pressure transient tests) data were identified. This approach and correlation is expected to be a useful tool for practitioners asit reduces the computational time in static model preparation significantly and utilizes the available data effectively. Introduction The two most common approaches proposed for model transport in fractured reservoirs (dynamic modeling) are single and dual-porosity models. These methods require grid based representation of fracture network properties like porosity and permeability. The discrete fracture network approach is morecapable of representing the complex nature of fracture networks but they are limited in modeling complex dynamic processes. Hence, an accuraterepresentation of a fracture network and its equivalent permeabilitydistribution is a crucial task in dynamic modeling.
- Asia (1.00)
- North America > United States > Texas (0.68)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (21 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)
- Information Technology > Communications > Networks (0.54)
- Information Technology > Software (0.34)
- Information Technology > Artificial Intelligence > Machine Learning (0.34)
Abstract Enhanced oil recovery from challenging/complex fields requires extensive analysis of reservoir structure and good understanding of the effect of this structure on the dynamics of the process. Naturally fractured reservoirs are good examples of this kind and their fracture network characterization is still a bigchallenge. In this study, we analyzed the fracture network system of a portion of the Midale Field, a naturally fractured carbonate reservoir in the Williston Basin of southeastern Saskatchewan, Canada. Our study aims at an extensive characterization of fracture and fracture network properties and construction of a reliable fracture network model for further use in assessing the oil recovery by CO2 injection and CO2 sequestration potential. We integrated static data such as cores, logs and well tests to build 3D discrete fracture network models. Stochastic numerical approach was applied using a commercial software package. A fracture network constructed from static data was calibrated using well test data. Several parameters were evaluated in sensitivity studies to determine those characteristics of the network which have higher influence on the reservoir performance. Simulated well test response was checked against previously published well test data. This study allowed us to recognize uncertainties in critical parameters and propose some measures to manage those uncertainties. Introduction The Midale is a carbonate field located in southeastern Saskatchewan. Following the discovery in 1953, the field was developed on 32 ha spacing and proved to bear 81.9 ? 10 Sm reserves of 28.7 °API oil. The field belongs to the Mississippian oil trend located along the northern margin of Williston Basin. Subsequent to primary production up to 1962, the field was subjected to waterflooding on 83 inverted nine-spot patterns. To maintain the production which declined after 1964, an intensive program of vertical and horizontal infill drilling was undertaken. As of the end of 2006, approximately 1,000 wells exist in the field and more than 25% of OOIP was produced with an average watercut of 92%. The Midale Field is currently being subjected to tertiary recovery by miscible CO2 flooding. This field-scale CO2 injection was preceded by a 1.78 ha pilot project in 1984 ? 1989 which paved the way for a larger demonstration project. The CO2 Flood Demonstration Project encompassed 10% of the Midale Unit and paved the way for the field-scale application, which is expected to end up with an incremental recovery of 15% of OOIP. The Midale Field does not meet typical screening criteria for CO2 flooding. Nevertheless, extensive research and field applications proved that a proper design based on the analyses of the special combination of petrophysical, lithological and fracturing data can result in a successful carbon dioxide flood. The 24 m thick Midale Reservoir section consists of two main layers: dolomite-dominated "Marly" and vugular limestone, called "Vuggy". Both strata contain systematic fractures, though the degree of fracturing varies. Numerous studies conducted on the field revealed some characteristics of the natural fracture network (NFN) by both inverse methods, such as waterflood and carbon dioxide flood performance analyses, and well test analyses and direct methods such as core and log analyses.
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.95)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Mission Canyon Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Madison Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Forbisher Formation (0.99)
- (5 more...)
Abstract Bitumen extraction in oil sands-ore water slurry systems was studied using lipids and lipid derivatives as surfactants to promote the efficiency of bitumen recovery. In this study canola oil, tall oil fatty acids (TOFA) which are by-products of pulp mills using the bleached Kraft process, canola oil fatty acids methyl esters which are known as biodiesel (BD), and canola oil fatty acids monoglycerides were used as surfactant additives. Experimental findings suggest that BD, i.e., fatty acids methyl esters, a blend of fatty acids methyl esters, and fatty acids monoglycerides could also be used as surfactant additives to increase the efficiency of bitumen recovery in thermal in-situ processes such as steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) processes. Our experimental findings showed that the required dosage for the surfactant additives would be about 0.1 % of bitumen by mass. Also, interfacial tensions between bitumen and process water (?B,W) and BD and process water (ϒ B,W) were provided as supportive data for the applicability of the method proposed. This paper presents the initial observations. Experiments at high pressure conditions and the analysis of bitumen recovery and produced water chemistry are currently in progress. Background Oil sands deposits in northern Alberta, Canada contain about 142×10 cubic meter cube (m) or 890×10 barrels of bitumen, which makes it one of the largest oil sands deposits in the world (AERCB, 1984). Four commercial plants are utilizing surface mineable oil sands deposits for bitumen production using oil-sands ore water slurry based extraction processes with total bitumen production capacity exceeding 10 barrels/day. Reduction of the surface and interfacial tensions play an important role in the efficiency of bitumen recovery in ore-water slurry systems (Moschopedis et al., 1977 and 1980; Speight and Moschopedis, 1977; Bowman, 1968; Baptista and Bowman, 1969), which are the basic reasons for the success of the Clark How Water Extraction (CHWE) process (Clark, 1939 and Clark and Pasternack, 1932). In the CHWE process, the solubility of naturally occurred asphaltic acids in bitumen which are partly aromatic, containing oxygen functional groups such as phenolic, carboxylic and sulphonic types are increased by the use of caustic NaOH, which act as surfactants reducing the surface and interfacial tensions. This process produces tailings with poor settling characteristics which result in the use of gypsum (CaSO4) as additive to alter its settling and consolidation properties. It is realized that the release water chemistry is harmed by the use of chemical additives in both extraction and tailings disposal processes (Allan, 2008 and 2008; Franklin et al. 2002). Novel extraction process aids, i.e. surfactant additives, have to replace the conventionally used additives, by which extraction efficiency would be improved without harming the fuel quality of bitumen, release water chemistry and geotechnical properties of the tailings. Our research was focused on the use of surfactants from external sources to eliminate the harmful effects of the additives used in the existing oil sands plants.
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract Our previous research on the effects of ultrasonic waves on oil recovery conducted at the University of Alberta had shown that capillarity and interfacial tension (IFT) might be responsible for the observed improvements in incremental oil recovery. Although the results seem encouraging, questions about the mechanism and effective parameters causing additional recovery still remain. To analyze the influence of parameters other than IFT and capillary forces, we conducted capillary imbibition experiments on cylindrical Berea sandstone core samples under ultrasonic radiation, and the results are presented in this paper. Through this experimental scheme, we focused on:the effect of initial water saturation for rocks with different wettability; oil viscosity; and matrix wettability. The cores were placed into imbibition cells where they were contacted with an aqueous phase. Every experiment was conducted with and without ultrasonic radiation for comparison. Different intensities of ultrasonic waves were tested as well. To investigate the acoustic interaction between rock and fluid, we performed certain visualization experiments. We used 2D glass bead models to clarify the effects of ultrasonic waves on the oil displacement process for different oil viscosities and matrix wettability through comparative analysis. The qualitative and quantitative observations and analyses presented are expected to provide additional understanding regarding investigations in the use of in situ recovery of oil/heavy oil, as well as surface extraction. Introduction Acoustic energy was considered as one of the unconventional EOR methods to replace or to be applied with conventional ones. Studies have been conducted to understand the effects of acoustic energy on oil recovery over the last four decades. Duhon and Campbell(1) performed waterflood tests of cores with ultrasonic energy and showed that the ultrasonic energy improved the oil recovery and displacement efficiency in the cores. Beresnev and Johnson performed a critical analysis of the work done in this area up to the early 1990s and provided a comprehensive review of the seismic and ultrasonic stimulation studies. They concluded that the elastic wave and seismic excitations of porous media affect permeability and production rates in most cases Kuznetsov et al. reviewed seismic techniques for enhanced oil recovery and observed an increase in oil/water relative permeabilities and also oil recovery after elastic vibration. They concluded that this increase is due to fines removal by vibration. Roberts et al. applied mechanical stresses to rock samples which were placed inside a core holder and observed changes in permeability and an increase in wettability in the non-wetting phase. There also exists field-scale applications of sound waves of different characteristics. Spanos et al. observed improvements in waterflooding and injectivity when pressure pulses were applied by a hydraulically-operated tool. Westermark et al. applied a complex system of vibration tools in the field and observed an improvement in permeability at certain intensities and up to a 20% increase in the oil production rate. Zhu et al. documented the results of the application of a special downhole vibration tool in several oil fields in China, pointing out that sand content, water content, viscosity and density of oil decreased after treatment.
- North America > United States (1.00)
- North America > Canada > Alberta (0.88)
Abstract Borehole ballooning or breathing is commonly observed during drilling through fractured zones. It refers to small, partial and continuous mud losses and significant rapid mud gains due to annular pressure fluctuations resulting from mud circulation and non-circulation. Better understanding of the factors controlling borehole ballooning and/or breathing is needed for correct interpretation of the symptoms observed while drilling and to avoid mixing this phenomenon with lost circulation and well kicks. This paper introduces a two dimensional transient model of borehole ballooning and/or breathing. The model considers the effects of Newtonian fluid rheology, and fracture roughness on the fracture volume change as a function of transient wellbore pressure fluctuations inherent in typical drilling operations. Different types of fracture surface roughness that are commonly observed in sedimentary rocks and the degree of roughness identified by a wide variety of fractal dimensions were considered. The model was solved numerically to investigate the effects of fractures' natural geologic properties (fracture roughness, fracture dimensions, fracture surface deformation law) on the fluid loss and gain rate between the borehole and the fractured formation. Analyses on the importance of fracture roughness and non-linear deformation approximations were provided and situations where the degree of roughness becomes critical were identified. Introduction Mud losses/mud gains have been a major problem in the drilling industry and the identification and treatment of this problem is still a crucial issue due to the high cost of the drilling operations. Several practical solutions have been recommended to avoid drilling fluid losses and gains. However, regardless of the type of treatment, significant rig time can be lost and these solutions can make the control of other drilling parameters required for a precise well design even more complicated. Borehole ballooning or breathing is a recognized combined mud loss and mud gain phenomenon referring to the small, partial and continuous mud losses and significant rapid mud gains due to annular pressure fluctuations resulting from mud circulation and non-circulation. If the bottomhole pressure or Equivalent Circulating Density (ECD) exceeds fracture initiation pressure during circulation, drilling mud starts to escape into the fractured formation and more mud is required to maintain the hydrostatic head. As soon as the dynamic wellbore conditions disappear and the ECD falls below the Fracture Initiation Pressure (FIP) during a pump-off period because of a connection or flow check operation, sizeable amount of mud is gained back into the wellbore. A large amount of mud gain from formation when pumps are turned off can be diagnosed as a well kick. This misjudgment and its likely treatments can lead to unnecessary costly well control procedures. Limited number of studies have been published about the mechanisms behind this phenomenon. According to Gill (1989), elastic deformation of the borehole wall due to the bottomhole pressure can explain this incident. Ram Babu (1998) proposed that expansion and contraction of the drilling fluid due to the temperature variations in the wellbore can be diagnosed as borehole ballooning.
- North America > Canada > Alberta (0.28)
- North America > United States (0.28)
Abstract CO2 sequestration into geologic formations such as oil reservoirs, coal beds and aquifers is a possible way to reduce the emissions of this anthropogenic gas into the atmosphere. Among these, sequestration into oil reservoirs while enhancing oil recovery is one of the most feasible ways as the additional oil recovery would offset the cost of CO2 sequestration operation. We postulate that the matrix, the main source of oil, could be a good CO2 storage medium. Hence, we focus on the matrix-fracture interaction during CO2 injection into naturally fracture oil reservoirs (the Weyburn and Midale fields are good examples for this case) in this paper. Proper design of this process is essential to maximize both the amount of CO2 sequestered and oil recovered. In this cooptimization process, miscibility, oil viscosity, matrix properties (permeability, porosity, pore characteristics, wettability, etc.), fracture properties (permeability, orientation, connectivity), injection rate, gravity, and the physical state of CO2 play a critical role. Clear understanding of the contributions of these properties on the dynamics of matrixfracture interaction is essential in designing EOR and CO2 sequestration application. In this paper, the dynamics of CO2 injection was studied experimentally. 2-D glass-bead models with a fracture in the middle were prepared and pentane was used as solvent to displace the kerosene or mineral oil to mimic miscible CO2 displacement. The focus was on the displacement patterns and solvent breakthrough controlled by matrix fracture interaction and pore scale behaviour of solvent-oil interaction for different matrix (wettability), fracture and injection conditions (rate, vertical vs. horizontal injection) as well as oil viscosity. Besides the visual investigation, the produced fluid was analyzed to calculate the solvent cut and oil recovery. It is believed that the visual understanding of the process will provide substantial information for further modelling studies. Introduction Miscible Displacement Mechanisms controlling the miscible displacement and factors effective on the efficiency have been focus of many studies over the last four decades. Huang and Tracht studied oil recovery mechanisms during CO2 injection and reported that the dominant controlling mechanisms are CO2 swelling and the CO2 extraction of oil. Bahralolom and Orr supported that through their micro model visualization study. They also suggested that the extraction is more effective than solubility. In general, the most common mechanisms controlling the oil recovery by CO2 injection are (1) oil displacement by the generation of miscibility, (2) oil swelling and (3) reduction in oil viscosity. Presence of water can decrease the efficiency of miscible CO2 displacements in water wet systems as the higher saturation of wetting phase decreases the flow fraction of nonwetting phase and consequently decreases the recovery of oil in water wet systems. Interaction of phase behaviour with heterogeneities leads to residual oil saturations due to preferential flow paths. In case of naturally fractured reservoirs, other parameters such as matrix and fracture properties critically influence the efficiency of displacement. Thompson and Mungan's study eveals the effect of displacement velocity on recovery efficiency. Later, Firoozabadi and Markeset showed that matrix-fracture configurations and fracture ap
- North America > Canada > Alberta (0.29)
- North America > United States > Texas (0.28)
- North America > Canada > Saskatchewan (0.24)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Mission Canyon Formation (0.93)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Madison Formation (0.93)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Forbisher Formation (0.93)
- (2 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract Our previous research on the effects of ultrasonic waves on oil recovery conducted at the University of Alberta had showed that capillarity and interfacial tension (IFT) might be responsible for the observed improvements in incremental oil recovery. To investigate this further, Hele-Shaw type experiments had been performed with the same fluid pairs, and significant alterations in the morphology of the fingers with ultrasonic waves were observed. Although the results seem encouraging, questions about the mechanism and effective parameters causing additional recovery still remain. To analyze the influence of parameters other than IFT and capillary forces, we conducted capillary imbibition experiments on cylindrical Berea sandstone core samples under ultrasonic radiation in this paper. Through this experimental scheme, we focused on (a) the effect of initial water saturation for different wettability rocks, (b) oil viscosity, and (c) matrix wettability. The cores were placed into imbibition cells where they contacted with aqueous phase. Every experiment was conducted with and without ultrasonic radiation for comparison. Different intensities of ultrasonic waves were tested as well. To profoundly investigate the acoustic interaction between rock and fluid, we further performed some visualization experiments. We used 2-D glass bead models to clarify the effects of ultrasonic waves on oil displacement process for different oil viscosities and matrix wettability through comparative analysis. The qualitative and quantitative observations and analyses are expected to shed light on the further investigations in the use of in-situ recovery of oil/heavy-oil as well as surface extraction. Introduction Primary production of petroleum by natural reservoir energy does not produce a large fraction of original oil in place. To increase the oil recovery from the reservoirs after conventional secondary recovery, enhanced oil recovery (EOR) techniques such as thermal, chemical and gas injection, should be implemented. In addition to those traditional EOR techniques, unconventional EOR methods have received a great deal of attention, especially after the recent increase in oil prices. Acoustic energy was considered as one of those unconventional EOR methods. Studies have been conducted to understand the effects of acoustic energy on oil recovery over the last four decades. Duhon and Campbell performed waterflood tests through cores under ultrasonic energy and showed that the ultrasonic energy improved the oil recovery and displacement efficiency in the cores. Beresnev and Johnson reported a critical analysis of the works done in this area by the early 1990's and provided a comprehensive review of the seismic and ultrasonic stimulation studies. They concluded that the elastic wave and seismic excitations to porous media affect permeability and production rate in most cases. Kuznetsov et al. reviewed seismic techniques for enhanced oil recovery. They performed capillary pressure measurements with and without vibration and observed an increase in oil/water relative permeabilities and also oil recovery after elastic vibration. They concluded that this increase is due to fines removal by vibration. Roberts et al. applied mechanical stresses to rock samples which were placed inside a core holder.
- North America > United States (1.00)
- North America > Canada > Alberta (0.88)
Abstract Enhanced oil recovery from challenging/complex fields requires extensive analysis of reservoir structure and good understanding of the effect of this structure on the dynamics of the process. Naturally fractured reservoirs are good examples of this kind and their fracture network characterization is still a big challenge. In this study, we analyzed the fracture network system of a portion of the Midale field, a naturally fractured carbonate reservoir in the Williston basin of south-eastern Saskatchewan, Canada. Our study aims at an extensive characterization of fracture and fracture network properties and construction of a reliable fracture network model for further use in assessing the oil recovery by CO2 injection and CO2 sequestration potential. We integrated static data such as cores, logs, and well tests to build 3-D discrete fracture network models. Stochastic numerical approach was applied using an emerging commercial software package (FRACA). Fracture network constructed from static data was calibrated using well test data. Several parameters were evaluated in sensitivity studies to determine those characteristics of the network, which have higher influence on the reservoir performance. Simulated well test response was checked against previously published well test data. This study allowed us to recognize uncertainties in critical parameters and propose some measures to manage those uncertainties. Introduction The Midale is a carbonate field located in southeastern Saskatchewan. Following the discovery in 1953, the field was developed on 80-acre spacing and proved to bear 515 MM bbl reserves of 28.7 °API oil. The field belongs to the Mississippian oil trend located along the northern margin of Williston basin. Subsequent to primary production up to 1962, the field was subjected to waterflooding on 83 inverted nine-spot patterns. To maintain the production declining after 1964, an intensive vertical and horizontal infill drilling was undertaken. As of the end of 2006, approximately 1000 wells exist in the field and more than 25% of OOIP was produced with an average watercut of 92%. The Midale field is currently being subjected to tertiary recovery by miscible CO2 flooding. This field-scale CO2 injection was preceded by a 4.4 acre pilot project in 1984–1989 which paved the way for a larger demonstration project. The CO2 Flood Demonstration Project encompassed 10% of Midale Unit and paved the way for the field-scale application, which is expected to end up with an incremental recovery of 15% of OOIP. The Midale field does not meet typical screening criteria for CO2 flooding. Nevertheless, extensive research and field applications proved that a proper design based on the analyses of the special combination of petrophysical, lithological and fracturing data can result in a successful carbon dioxide flood. 24-meter thick Midale reservoir section consists of two main layers: dolomite-dominated "Marly" and vugular limestone, called "Vuggy". Both strata contain systematic fractures, though the degree of fracturing varies. Numerous studies conducted on the field revealed some characteristics of the natural fracture network (NFN) by both inverse methods such as waterflood and carbon dioxide flood performance analyses, and well test analyses and direct methods such as core and log analyses.
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Mission Canyon Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Madison Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Forbisher Formation (0.99)
- (5 more...)