| This area in this study is located in The south central Sichuan Basin, and the targetlayer is Permian System Maokou formation. According to exploration status of the workarea, based on theory of sequence stratigraphy, this study clarifies in the futher of theThe south central Sichuan Basin work area Permian sequence stratigraphic frameworkand its evolution, established third-order-sequences stratigraphic framework inPermian System Maokou formation of work area, makes an analysis of sedimentarycharacteristics and its tectonic significance in sequences critical interface formationand makes a research on Permian sedimentary facies. Next, this study summarizes thebasic characteristics of the reservoir from the physical characteristic, pore throatcharacteristics, pore types, analyzes the effect of sedimentary microfacies to reservoir.In the integrated sequence stratigraphy, sedimentary facies distribution and reservoiron the basis of thin sections identification results,which is used for forecasts the favoraccumulation facies belt.Since Paleozoic Marine deposit, Sichuan basin in late Triassic period to thebeginning of a wider continental deposit, according to characteristics of basin tectonicevolution, usually its evolution is divided into four period.To control thesedimentation in The south central Sichuan Basin of tectonic movement is Liujiangriver movement, Yunnan movement and Dongwu movement between middle Permianand upper Permian.Liujiang river movement and Yunnan movement formed Angleunconformity between the Liangshan formation and the underlying strata, Dongwumovement formed parallel unconformity with the Maokou formation and overlyinglongtan group. According to some main partitioning signs of sedimentary facies, such aslithology, sedimentary characteristic, paleontological characteristic， particle sizeanalysis，logging characteristic and so on, the author studies the sedimentary facies ofmiddle Permian in The south central Sichuan Basin work area. Maokou formation ofPermian system in the study area is a transgressive-regressive deposits, sedimentarysequence in the order in from sedimentation of MAO1period to MAO2-MAO4period is deep-water ramp platform deposits to Shallow gentle slope platformdeposits.By selecting32drilling focus wells in work area, this study makes (9the coreobservation wells) the well profile comparison, seismic sequence boundariescalibration, third-order sequences and their systems tracts interface identification,tracking, and establishes Permian third-order sequences stratigraphic frameworkwithin the work area. The middle Permian of the Maokou formation in The southcentral Sichuan Basin work area is divided into one Supersequence SSQ1. Theresidual deposition time was about20Ma; Maokou formation contains onethird-order sequences which includes SQ1,The residual deposition time was about10Ma. Sequence boundaries identification includes angular unconformity, orogenicuplift unconformity and erosional unconformity. According to datum (lake level)changes, the depositional model can be summarized into two kinds, namelytransgressive mode, high mode. Based on research of backbone well profile, we studythe spread of sedimentary facies and the main controlling factors in sequence frame.Through seismic facies depict as Single well sedimentary facies constraint andconverted into sedimentary facies. Finally, compile Sedimentary facies plan anddisclose sedimentary facies regulation.Tectonic movement and datum lift are the main controlling factor in the the Thesouth central Sichuan Basin work area of middle Permian of the Maokou formationwhich is two,The performance of control with Tectonic movement of middle Permianin The south central Sichuan Basin study area is to build bottom orogenic Angleunconformity interface in bottom of Liangshan formation and parallel unconformityinterface in uplift of Maokou formation. The datum (lake level) lift controls athird-order sequence cycles succession, and thus controls the third-order sequencesinternal sedimentary facies distribution. |
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