Integrated Characterization of a Tight Sandstone Gas Reservoir: Member 8 Permian Shihezi Formation, Su49-01 Block, Sulige gas field, Ordos Basin, China

Sulige is a tight sandstone gas field in Ordos Basin, North China, whose main gas bearing interval is Upper Permian 8th member of Shihezi Formation, a braided river deposition with low porosity and permeability. The... [ view full abstract ]

Sulige is a tight sandstone gas field in Ordos Basin, North China, whose main gas bearing interval is Upper Permian 8th member of Shihezi Formation, a braided river deposition with low porosity and permeability. The sedimentary micro-facies change quickly, and the thickness of sand-bodies is usually thin, which bring great difficulties to the predication of effective reservoirs. In this paper, we propose a method of characterization the tight sandstone gas reservoir with comprehensive analysis of well log and seismic data of Su49-01 Block, a test area in south of Sulige Gasfield.
A series of techniques were used to identify the tight reservoir as follows: (1) Based on wireline logs and property analysis, lithofacies were identified by means of neural network, which mainly deposited in the inner part of channel bar and at the bottom channel lag microfacies.8th member of Shihezi was featured by low accommodation space, and the channel was stable, channel lateral cutting was superimposed, large area contiguous sand-bodies were formed as a result; (2)Sand-bodies less than 5m thick were predicted by seismic inversion constrained with well logs combined with seismic strata slice attributes analysis. The high quality reservoir was patchy extend from north to south, and only at the bottom of the river. The size of mid-channel bar was small and the distribution density was large, and as a result the physical property of the reservoir was good and basically make the effective reservoir standard;(3)The dynamic data of production, the cumulative gas production, producing reserves and oil recovery ratio were utilized to verify the architecture of the reservoir sand-bodies.
Testing the method of integrating static and dynamic information confirmed that the methodology of this paper was applicable to characterization of the similar tight sandstone gas reservoirs with low permeability.