Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (4): 992-1001.doi: 10.11743/ogg20210419

• Methods and Technologies • Previous Articles     Next Articles

Exploration and prediction of promising fault-fracture reservoirs in the Xujiahe Formation, northeastern Sichuan Basin

Wei Wang1(), Rui Fan2, Chengyin Li1, Dapeng Qu1, Lamei Zhang1, Kelu Su1   

  1. 1. Exploration Institute of SINOPEC Exploration Company, Chengdu, Sichuan 610041, China
    2. SINOPEC Exploration Company, Chengdu, Sichuan 610041, China
  • Received:2021-03-02 Online:2021-08-28 Published:2021-08-27

Abstract:

Tight sandstone in the Upper Triassic Xujiahe Formation, northeastern Sichuan Basin, has been one of the exploration targets for natural gas in the area. However, the stone, as a whole, is rather tight, deeply buried and highly heterogeneous, making commercial development of gas from it quite a challenge. The formation contains many fault-fracture gas reservoirs in the Tongjiang-Malubei area of the Tongnanba structural belt, where certain lithological facies in well-fractured zones may be used as clues to the whereabouts of the reservoirs. By recognition of source rock-rooted faults based on dynamic structure restoration, nonlinear inversion and prediction of lithology and physical properties, and multi-scale fusion as well as five-dimensional pre-stack fracture prediction in OVT domain, we effectively addressed the recognition of source rock-rooted faults, the prediction of relatively high-quality reservoirs and fractures as well as "sweet spots"-several issues easily encountered in dealing with this type of reservoir. These techniques were applied well to the predication of fault-fracture reservoirs in the northeast Sichuan Basin with prediction error of reservoir thickness being reduced from 16% to 8% and predication accuracy of fractures being increased from 60% to 85%. Four wells were so successfully drilled according to the predication results that controlled reserves of 367.91×108 m3 were booked with a possible gas resource base of 100 billion cubic meters readily on the way.

Key words: source rock-rooted fault, reservoir prediction, tight sandstone, Xujiahe Formation, fault-fracture body, Sichuan Basin

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