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Results
Investigation of Fautls Geomechanical Activity and Its Application to Development Program Optimization in Kelasu Gas Field in Tarim Basin
Jiang, Tongwen (Tarim Oilfield Company, Petrochina) | Zhang, Hui (Tarim Oilfield Company, Petrochina) | Wang, Haiying (Tarim Oilfield Company, Petrochina) | Yin, Guoqing (Tarim Oilfield Company, Petrochina) | Yuan, Fang (Tarim Oilfield Company, Petrochina) | Wang, Zhimin (Tarim Oilfield Company, Petrochina)
Abstract The Kelasu gas field located in northern Tarim Basin had experienced four tectonic evolutions, with the most intense deformation between northern margin of the basin and southern Tianshan Mountains. A series of sandstone faulted anticline gas reservoirs were produced after the Himalayan movement. Faults were the main channel to transport natural gas from Jurassic coal-bearing formation to sandstone reservoir in Cretaceous. Simultaneously, the faults play a key role for fluid flow during the development of the gas field, but it is a huge challenge to evaluate the influence of faults on fluid flow quantitatively with depletion. To solve this problem, an integrated research combined geology, geomechanics and gas reservoir engineering was conducted. Firstly, 6 geological factors associated with connectivity and sealing properties of faults was analyzed to determine the critical factors among them. Secondly, based on 4D geomechanical modeling and 3D stress analysis of faults' plane, a calculation model of faults geomechanical activity index (FGAI) was built. Finally, the relationships between faults geomechanical activity and performance of gas field development were investigated to understand the influence of faults' mechanical behavior on production and water invasion during development in Kelasu gas field. It is shown that faults geomechanical activity has profound influence on the performance of Kelasu gas field. โThe faults geomechanical activity is one of key factors to control permeability, which can indicate the difference of permeability around faults and permeability variation during depletion. โWith the depletion during exploitation the in-situ stress regime in Kelasu gas field changed from strike slip to normal faulting, and the heterogeneity was also gradually increasing which two resulted in the variety and complicate of faults' geomechanical activity. โIt is found that there is a good correlation between the faults geomechanical activity and water invasion. The water breakthrough was early and gas-water interface rose fast near the faults with higher geomechanical activity index during depletion. โThe complex relationship between stress field and faults system resulted in a great difference of faults geomechanical activity index in different location of reservoir. FGAI (Faults geomechanical activity index) is the highest in western reservoir, followed in turn by the eastern, northern, southern, so there is the most rapid uplift of gas-water interface in the western, followed in turn by other parts. Based on evaluation of faults geomechanical activity in this area, this reservoir could be divided into three blocks by different water invasion risk. Areas and gas wells with high risk water invasion were warned in advance. โ For optimization of well placement, we found that FGAI is relatively low in northwestern reservoir, the fault sealing ability is high, the research provided one of basis for the placement of a new gas well. A fault geomechanical activity index (FGAI) model for the gas reservoir with complex structure and high pore pressure and high in-situ stress was established. And its validity and effectiveness toward development of gas field was proved by production data and information. Based on the quantitative classification and description of faults geomechanical activity to investigate the influence of faults on water invasion, the mechanism of heterogeneous water production was determined in Kelasu gas field. The research provided the sealing evaluation of faults for new wells placement and risk prediction of water breakthrough for gas wells during depletion.
- North America > United States (1.00)
- Asia > China > Xinjiang Uyghur Autonomous Region (1.00)
- Phanerozoic > Cenozoic (0.93)
- Phanerozoic > Mesozoic > Jurassic (0.34)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.89)
- Geophysics > Borehole Geophysics (0.92)
- Geophysics > Seismic Surveying (0.67)
- Asia > Indonesia > Sumatra > South Sumatra > South Sumatra Basin > Palembang Basin > Corridor Block > Suban Field > Talang Akar Formation (0.99)
- Asia > Indonesia > Sumatra > South Sumatra > South Sumatra Basin > Palembang Basin > Corridor Block > Suban Field > Fractured Basement Formation (0.99)
- Asia > Indonesia > Sumatra > South Sumatra > South Sumatra Basin > Palembang Basin > Corridor Block > Suban Field > Durian Mabok Formation (0.99)
- (7 more...)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Challenging Reservoir Modeling Case Study for Naturally Fractured High-Pressure-High-Temperature Gas Sand Reservoir
Wang, Zhenbiao (Tarim Oilfield Company-PetroChina) | Wang, Haiying (Tarim Oilfield Company-PetroChina) | Li, Qing (Tarim Oilfield Company-PetroChina) | Cui, Xiaofei (Optimization Petroleum Technology, Inc.) | Huang, Xuri (SunRise PetroSolutions Technology, Inc.) | Bahar, Asnul (Kelkar & Associates, Inc.) | Kelkar, Mohan (The University of Tulsa)
Abstract This paper presents the development of a static model for a naturally-fractured High-Pressure-High-Temperature (HPHT) gas sand reservoir located in the Tarim basin, Western China. The study is part of a well placement optimization study. It is motivated by the big challenges of drilling a well at depths ranging from 6800m-8000m[AG1] in a HPHT environment. A detailed fine-scale model is required as input for the dynamic model. The static model is developed through an integration [AG2]process. It consists of both matrix and fractures. The matrix modeling started by integrating 3D seismic and log data to build the structural model. A new rock type scheme was developed by reconciling log and core data, including capillary pressures. Additionally, permeabilities are estimated at each uncored location using a two-step approach, namely trend estimation by regression analysis and variability simulation by 1D Gaussian simulation. The 3D modeling was executed in the order of least dependent to most dependent variable (i.e., from facies, to rock type, then followed by porosity, permeability and saturation respectively). From the geology, the sand bodies were interpreted to be continuous throughout the field. Discontinuous mudstone layers are sandwiched in-between the sand bodies. This information, together with outcrop data, is used to guide the spatial relationships in the model. Facies, rock type, porosity and permeability are simulated using geostatistical procedures. Meanwhile, saturation is generated based on the Leverett J-Function. To quantify the uncertainty in the various data, especially in the capillary pressure data, the porosity-permeability relationship, the gas-water contact and the surface tension of the gas-water system, a probabilistic model of the Gas Initially in Place (GIP) is created through uncertainty and sensitivity analysis. The origin of the fracture system was analyzed by developing a prototype of a conceptual model. The understanding from the prototype model is coupled with the 3D seismic, outcrops, drilling information, rock mechanics, image log, core, and dynamic data, to develop fracture characteristics and correlations. The discrete fracture system is modelled using a stochastic simulation approach, constraining it to the seismically-inverted fracture density map for each zone through well-seismic correlations and a nonlinear inversion [AG3]to build the Discrete Fracture Network (DFN). Finally, the fracture model is integrated with the matrix model by upscaling the DFN model into the grid system. Following the creation of the static model, a dual porosity model was prepared for dynamic modeling by maintaining consistency between the fine scale and upscaled models throughout the upscaling process. The methodology described above has produced a detailed fine scale model that shows consistency between properties and geology. This is a direct consequence of the new rock type system and the order in which the simulation was conducted. The facies model shows the continuity of the sand bodies, and the discontinuity of the mudstone, as indicated by the geological interpretation. The 3D Poro-Perm relationship shows the variability which is a reflection of the variability of the core data. The probabilistic distribution of the GIP is in agreement with the results of conventional reservoir engineering analyses, namely Material Balance and Rate Transient Analysis. Furthermore, the fracture distribution confirms the information both at the wells, as well as in-between the wells as given by the seismic interpretation. This study demonstrates that a reliable fine scale model can be developed to match the available data and interpretation by properly preparing the pre-requisite inputs and following the order of dependency in the reservoir attributes.
- Asia > China (0.86)
- North America > United States > Texas > Dawson County (0.24)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.44)
- Geophysics > Seismic Surveying > Seismic Interpretation (0.34)