| Su14 wellblock in Sulige gas field is an important resource exploration area, The main producing gas reservoir is the member 8 of lower Shihezi formation. Reservoir sands is large gentle slope shallow water delta deposition, delta sand body distribution widely, But the lateral distribution of sand extremely discontinuous, longitudinally mutually stacked, gas sands is difficult to identify, the scope of gas is difficult to determine quantitative criteria, reservoir heterogeneity is strong, serious impact on the effect of natural gas development in the region. Based on the above problems, the present paper on the basis of previous research, core observation, geophysical logging data, seismic data and geochemical data analysis, the use of sedimentology, reservoir geology, petroleum geology theory as a guide, systematically studied the sedimentary micro facies and reservoir macroscopic heterogeneity features of the meber 8 in su 14 wellbock sand body, fine described sand scale, longitudinally stacked relationship, horizontal distribution characteristics and spatial variation of the reservoir, obtained followling understanding :(1) Research together with rock color, structure, construction, paleontological and geochemical paleosalinity, can be inferred the meber 8 formation is seasonal continental facies-land and sea transitional facies shallow river depositional environment.Based on cross-sectional structure and logging facies, seismic facies mark, know MSC1-MSC3 development middle cycle braided river delta plain sediments, sedimentary microfacies are distributary channel and split between depression; MSC4 mid-cycle development meandering river delta plain, sedimentary microfacies natural levee, crevasse splay, shunt river, delta plain sediments.(2) MSC1 and MSC2 mid-cycle sand body is braided river distributary channel a plurality of stacked, large thickness, sand body in the plane showed a blanket distribution of a large area near the north and south. MSC3 mid-cycle sand body extend smaller, thinner, sand belt width in the plane is smaller than the MSC1 and MSC2 mid-cycle.MSC4 mid-cycle scale of sand body extending transversely reduce, thin, vertical muddy dissection and compartment increased, mostly sand body showed isolated state, from north to south on the plane distribution of thin banded.MSC1-MSC3 mid-cycles braided river delta plain sand body distributary channel sand body the distribution good, between the lateral overlaid on each other sand body often separated by fine-grained sandstone and mudstones, limiting the sand body transverse continuity and connectivity, single channel sand bodies are able to form gas reservoirs their own independent, a plurality of channel reservoir sands can form several independent gas reservoirs coexist;MSC4 mid-cycle meandering river delta plain of sand body due to the shunt between depression large-area distribution led to channel dividing each other, thus preventing the connectivity between sand body, but at different times of the plurality of sedimentary distributary channel sand bodies in the vertical continuous stacked development,still form favorable reservoir sand bodies.(3) Macroscopic reservoir heterogeneity study shows that the whole meber 8 formation sandstone reservoir showed strong heterogeneity. MSC1 mid-cycle sand body connectivity best, high physical properties condition and heterogeneity, developed less mezzanine, medium physical properties condition but The heterogeneity is good, so the heterogeneity is weakest. MSC2 mid-cycle sand body connectivity is better, higher stratified coefficient and low sandstone density, developed less mezzanine, medium physical properties condition and heterogeneity, so the heterogeneity is weak. MSC3 mid-cycle sand body connectivity is poor,low stratified coefficient and low sandstone density, developed less mezzanine, medium physical properties condition and heterogeneity, so the heterogeneity is strong. MSC4 mid-cycle sand body connectivity is the worst, low stratified coefficient and low sandstone density, developed more mezzanine, medium physical properties condition but The heterogeneity is poor, so the heterogeneity is the strongest. |
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