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Results
Summary A realistic surface-to-borehole controlled-source electromagnetic (CSEM) survey was modelled to determine the sensitivity of electromagnetic fields to waterflooding in a typical Saudi Arabian carbonate oil reservoir. The reservoir saturation changes were modelled over a period of 75 years and then converted to resistivity using Archie's empirical relation. The overburden model is obtained by upscaling tri-axial resistivity logs from a test well to derive a full anisotropic profile from surface to the reservoir level. 3D Finite Difference (FD) frequency-domain modelling was performed assuming surface galvanic sources with radial and tangential polarization directions relative to the well and with receivers positioned in the reservoir. Forward modelling and inversion results indicate that electric field measurements in the borehole and the vertical component of it (Ez), in particular, may offer the necessary resolution and sensitivity to characterize reservoir saturation variations.
- North America > United States (0.48)
- Asia > Middle East > Saudi Arabia (0.15)
- North America > United States > California > San Joaquin Basin > Lost Hills Field (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Statfjord Group (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Lunde Formation (0.99)
- (13 more...)
Summary Low-frequency shadow is generally used as a hydrocarbon indicator in the application of spectral decomposition. Recently, it was pointed out that carbonate reservoir often exhibits high-frequency anomaly. In the practice on cavern carbonate reservoir characterization using high-resolution deconvolutive short-time Fourier transform (DSTFT) based spectral decomposition, we encountered both low-frequency shadows and high-frequency anomalies associated with high porosity and relatively thick cavern carbonate reservoirs. The low-frequency shadows usually occur beneath cavern reservoirs, while the vertical distribution of the high-frequency anomalies is in reasonably good agreement with the distribution of the cavern carbonate reservoir revealed by the impedance inversion profile. In other words, spectral anomalies could roughly delineate the top and bottom of the cavern carbonate reservoir. For more than 20 oil wells which encounter cavern carbonate reservoirs in target area, Tarim Basin, Northwest China, we observed low-frequency shadows and high-frequency anomalies. Our work indicates that the combination of low-frequency shadows and high-frequency anomalies could be used as a new hydrocarbon indicator for cavern carbonate reservoirs. And we also discuss its existing conditions.
Study Geophysical Response of Middle East Carbonate Reservoir Using Computational Rock Physics Approach
Zhan, Xin (ExxonMobil Upstream Research Company) | Fullmer, Shawn M. (ExxonMobil Upstream Research Company) | Lu, Chih-ping (ExxonMobil Upstream Research Company) | Kaczmarek, Stephen E. (ExxonMobil Upstream Research Company) | Harris, Christopher E. (ExxonMobil Upstream Research Company) | Martinez, Alex (ExxonMobil Upstream Research Company)
Summary Development of carbonate rock physics model is difficult because pore systems are more complex in carbonate than they are in clastics. The best way to describe pore structure is through 3D µCT image of rock pore space. Instead of traditional effective medium based modeling by taking assumption of pore geometry, we adopt computational rock physics approach in this study. Multi-resolution µCT images are taken for carbonate cores belonging to different facies from middle east carbonate reservoir. Electrical conductivity and elastic properties (Vp, Vs) are computed on 3D rock micro-tomographis using finite difference (FD) and finite element method (FEM). To further extend predicting capability, a family of 3D model granular porous media with different porosity, pore (grain) aspect ratio, pore (grain) size distribution, pore connectivity and spatial arrangement are built to represent different carbonate petrophysical pore types. Modeling results compare well with core, log measurements. Direct link between rock microstructure and its elastic, electrical behavior is built up using computational rock physics. Finally, AVO forward modeling is built to quantify porosity, fluid saturation and lithology (facies) effect on seismic response for middle east carbonate reservoir.
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
Summary Occurrence of moldic and vuggy pores, fractures and other pore structures due to diagenesis in carbonate rocks much complicates the relationships between impedance and porosity. Acoustic impedance in carbonates is influenced by factors such as porosity, pore structure/fracture, fluid content, and lithology. Using a frame flexibility factor (?) derived from a poroelastic model to characterize pore structure in reservoir rocks, we found that its product with porosity could result in a much better correlation with sonic velocity (Vp = A-B*??) and acoustic impedance (AI = C-D*??), where A, B, C and D is 6.60, 3.14, 18.21, and 9.88 respectively for a deep low-porosity carbonate reservoir studied in this paper. These new relationships could also be useful to improve seismic inversion of ultra-deep hydrocarbon reservoirs in other similar environments.
- Asia (0.97)
- North America > United States > Texas (0.29)
- North America > United States > Mississippi > Marion County (0.25)
- 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)
- (22 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Carbonate reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.96)
Summary In most unconventional reservoirs, open fractures provide critical fluid conduits, and therefore, hydrocarbon production is heterogeneous and strongly dependent on the proximity of wells to the fractures. Attributes such as curvature do not "see" fractures; rather they are direct measures of real or apparent folds and flexures that are associated with. In this study, we extend a previously-developed, interpreter intensive workflow to generate a suite of azimuthally-limited attribute volumes that are sensitive to fracture orientation and intensity and can be directly correlated to production. Specifically, we cross correlate the strength and strike of curvature lineaments to production based on the hypothesis that production will be a function of the well’s distance to "fractures" correlated with curvature. We validate this workflow on a 3D seismic survey acquired over a Mississippian supermature carbonate reservoir in Dickman Field, Ness County, Kansas that was previously interpreted by explicit hand correlation. After calibration of the hypothesized fluid flow based on the strength and strike of the most-negative principal curvature, we find oil production increases with increasing distance from sealed NE-trending fractures while water production decreases with increasing distance from open NW-trending fractures.
- North America > United States > Oklahoma > Arkoma Basin > Cana Woodford Shale Formation (0.99)
- North America > United States > Oklahoma > Anadarko Basin > Cana Woodford Shale Formation (0.99)
- North America > United States > Kansas > Dickman Field (0.99)
- (25 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 Characterization > Seismic processing and interpretation (1.00)
- Production and Well Operations (1.00)
Optimized 3D VSP Processing for Improved Structural Definition: Kuwait Case Study
Rao, Narhari Srinivasa (Kuwait Oil Company) | Al-Ashwak, Samar (Kuwait Oil Company) | Kidambi, Vijaya Kumar (Kuwait Oil Company) | Laiq, Kamran (Schlumberger Kuwait) | Kurniawan, Hari (Schlumberger Kuwait) | Ali, Shujaat (WesternGeco) | Campbell, Al (WesternGeco) | Menkiti, Henry (WesternGeco) | Nutt, Les (WesternGeco)
Summary An extensive 3D VSP campaign was undertaken in one of the deep wells of the Sabriyah field in Kuwait. The objectives of the VSP were high-resolution imaging of a deep carbonate formation (over 15000ft deep) and to further analyze the VSP data to deduce anisotropy and information on maximum and minimum stress directions in the area. A 100-level three-component array tool was used to record the 3D vertical seismic profile (VSP) using a vibroseis source (Dutta et al., 2010). The initial processing of the dataset was revised using new processing flows, including a new application of statics and common image point (CIP) tomography, to optimize 3D VSP imaging. Maximum and minimum stress directions were determined by further analysis of the VSP data. The improved image and stress information provided a valuable aid to reservoir interpretation in the area.
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Upper Marrat Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Sargelu Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Sabiriyah Mauddud (SAMA) Formation (0.99)
- (6 more...)
Abstract The Canadian energy sector pioneered and developed industry-leading oil- and liquids-rich reservoir acidizing technology. This involved new acid additive chemistry and completion techniques. However, many of the newer technical professionals in the industry have not been exposed to this technology. The first section of this paper outlines acidizing technology, with a focus on application to current new opportunities. Many of the current oil- and liquids-rich plays involve naturally fractured carbonate reservoirs. Acid treatments designed to enhance the conductivity of the existing fracture system can provide more-effective reservoir drainage than proppant fracturing treatments. The second section of this paper discusses how new placement techniques can offer more-effective zonal isolation while reducing completion time and associated costs, and how acid pre-pads can also reduce breakdown pressures and help minimize near-wellbore (NWB) tortuosity effects in many shale and sandstone reservoirs.
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.54)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.46)
Geomechanics Considerations in Enhanced Oil Recovery
Teklu, Tadesse Weldu (Colorado School of Mines) | Alameri, Waleed (Colorado School of Mines) | Graves, Ramona M. (Colorado School of Mines) | Tutuncu, Azra N. (Colorado School of Mines) | Kazemi, Hossein (Colorado School of Mines) | Alsumaiti, Ali M. (The Petroleum Institute)
Abstract Geomechanics plays significant role in decisions regarding all phases of exploration and production of oil and gas. Specifically, geomechanics influences prospect appraisal, field development, and primary, secondary, and tertiary production activities. Injection of enhanced oil recovery (EOR) fluids such as polymer, steam and gas/CO2 affect reservoir stress redistribution and re-orientation in the field. Hence geomechanics studies need to be conducted in every step of the EOR processes, from EOR screening to abandonment. This paper reviews geomechanical issues related to polymer, steam and hydrocarbon gas/CO2 continuous and water-alternating-gas flooding both in sandstone and carbonate formations. A number of published laboratory and field case studies will be presented and discussed in regard to geomechanics issues. The geomechanical effects pertinent to waterflooding and EOR processes in unconventional reservoirs such as shale reservoirs and oil sands will also be discussed. Finally, reservoir properties affected by stress changes and how to incorporate it in reservoir modeling will be discussed.
- North America > United States > Texas (1.00)
- Europe > Norway (0.68)
- Asia > Middle East > UAE > Abu Dhabi Emirate > Abu Dhabi (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.89)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.35)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > Middle East Government (0.46)
- North America > United States > Wyoming > Powder River Basin > NPR-3 > Teapot Dome Field > Wall Creek Formation (0.99)
- North America > United States > Wyoming > Powder River Basin > NPR-3 > Teapot Dome Field > Tensleep Formation (0.99)
- North America > United States > Wyoming > Powder River Basin > NPR-3 > Teapot Dome Field > Sussex Formation (0.99)
- (12 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Carbonate reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- (7 more...)
Integrated Approach to Unconventional Reservoir Characterization: Key for Understanding Hydrocarbon Production Challenges in Kerogen and Tight-Fractured Deep Carbonate Complex in Kuwait.
Acharya, Mihira N. (Kuwait Oil Company) | Kabir, Mir R. (Kuwait Oil Company) | Al-Ajmi, Saad H. (Kuwait Oil Company) | Al-Maia, Noura A. (Kuwait Oil Company) | Kumar, Ashok (Kuwait Oil Company) | Pradhan, San P. (Kuwait Oil Company) | Al-anzi, Ealian H. (Kuwait Oil Company)
Abstract The unique Kimmeridgian-Oxfordian complex of unconventional and fractured carbonates has been tested to be prolific producer of gas, condensate and light oil in different wells discovered in various North Kuwait fields. The challenge is to characterize the complex reservoir flow system where critical reservoir parameters such as reservoir type, porosity and permeability characteristics, and production and pressure data can vary substantially. The relationship between the natural fractures and the tight matrix in controlling effective system conductivity in reservoir flow units are the key features which dictate the nature of inflow mechanisms thus the production performance. The paper deals with developing an effective methodology which integrates the variations in critical reservoir properties of the low porosity yet naturally-fractured carbonate reservoir. The drill stem test (DST) results in some wells were successful without stimulation, while in other wells the DSTs were unsuccessful in spite of advance and repeated stimulations, thus categorizing these plays as geologically-complex, tight gas condensate reservoirs where out of ordinary stimulation techniques may be needed to activate the fractured matrix. Pressure transient analyses and flow regime interpretation of the successfully-tested wells confirm the dual porosity flow-system and the fractured nature of the reservoir. In this paper, the authors will discuss a new integrated approach for understanding the production and pressure behavior in light of the unique unconventional reservoir characteristics along with the fractured reservoir properties. Dual-layer and dual poro-perm models for pressure transient analysis have been applied extending the previous study of relationship developed between the productivity index (PI) and the total organic carbon (TOC). The proposed integrated methodology can significantly improve the current approach to production optimization, reservoir management strategy, completion, and stimulation design in fractured tight gas condensate reservoirs in Kuwait as well as in other regions.
- Geology > Petroleum Play Type > Unconventional Play (0.49)
- Geology > Mineral (0.47)
- Geology > Geological Subdiscipline (0.46)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Gas-condensate reservoirs (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Carbonate reservoirs (1.00)
- (2 more...)
Stimulation of Tight Gas Reservoir using coupled Hydraulic and CO2 Cold-frac Technology
Mueller, Martin (Technical University Bergakademie Freiberg, Germany) | Amro, Mohammed (Technical University Bergakademie Freiberg, Germany) | Haefner, Frieder Karl (Technical University Bergakademie Freiberg, Germany) | Hossain, Md Mofazzal (Curtin University, Perth, Australia)
Abstract Conventional hydraulic fracture stimulation technique has been widely used to enhance the production from tight gas reservoirs. Success of this technique, however, substantially depends on fracturing fluids and it responses to fracturing fluid-in the treated formations. This technology predominantly has been used to stimulate the tight sandstone reservoir. There are very limited applications for low permeable tight carbonate reservoirs due to complexities associated with the physical and mechanical properties of carbonate rocks and its interaction with fracturing fluid. This study has been focused on the development of a new fracture stimulation technique especially for tight carbonate reservoir, where the fracture will be created by hydraulic pressure and cold CO2. This paper presents a numerical model that has been developed to simulate the stimulated fracture created by proposed technology with an emphasis on the evaluation of the relative permeability of supercritical CO2, brine/liquid CO2, created achieved fracture porosity and permeability; and the prediction of the production performance of stimulated fractures. Numerical simulation employing the development model has been conducted to: understand the science; investigate the thermo-hydro-fluid-mechanical behaviour; and identify the key parameters influencing the production performance for tight carbonate reservoirs using representative field data. The potential field application of the proposed technique for other formations such as tight sand and shale plays including adsorption effects on the shale and displacement efficiency of CO2 and advantages of this technique are also elaborated in this paper.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.89)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.54)