地质科技通报 (Mar 2024)
Fracture characteristics of ultra-deep tight sandstone reservoirs in the Bozi Block, Kuqa Depression of Tarim Basin, and effects on oil-gas production
Abstract
Objective Natural fractures are important oil-gas migration channels and reservoir spaces in deep tight sandstone reservoirs and significantly affect oil-gas production capacity in the Bozi Block of the Kuqa Depression. Methods Based on rock core, thin slice, imaging log, and actual production data, the development characteristics of natural fractures in ultra-deep tight sandstone reservoirs in the Bozi Block, Kuqa Depression of Tarim Basin were clarified, and the effects of natural fractures on oil-gas production capacity were explored. Results Tectonic fractures developed in the ultra-deep reservoirs of the Bozi Block and were dominated by unfilled to semi-filled high-angle shear fractures accompanied by locally developed semi-filled to filled extensional fractures. Under the influence of multiphase tectonic movements, the natural fractures were mainly oriented N-S direction and NW-SE directionand partially oriented nearly E-W direction. Fractures are important reservoir spaces and seepage channels in the study area. Then, the fracture development coefficient and fracture validation coefficient were determined by using imaging log data and oil testing data, which were used to quantify the effects of fractures on oil and gas production. Quantitative evaluation plots between these two coefficients and gas-oil production were established. Validation showed that the fracture development coefficient and fracture validation coefficient can better evaluate the validity of fractures in the study area. Therefore, the classification and prediction of fracture-type reservoir quality based on fracture parameters were achieved. Conclusion This study not only provides a geological basis for efficient oil-gas exploration in the study area but also provides insight into how tight sandstone reservoir fractures affect oil-gas production.
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