Study On High-resolution Sequence Stratigraphy In Deep Conglomerate Gas Reservoirs And Favorable Reservoir Prediction

The deep conglomerate gas reservoir is buried deeply; Its composition is complex; digenesis is strong and distribution is complex. The reservoir prediction and reservoir characteristics become the most critical constraint issues for gas field development. Taking Songliao Basin Xujiaweizi fault subsidence as a target area, using high-resolution sequence stratigraphy and reservoir sedimentation theory, the deep conglomerate gas reservoir sequence division, sedimentary and diagenetic features, reservoir physical property control factors and favorable reservoir distribution are deeply studied which can provide an important geological basis to field evaluation and development program design.Conglomerate reservoir is provided with a thickness changing quickly, large thickness and lithology single, poor separability in vertical, layered interface less, poor logging curves stratified, seismic can not distinguish the characteristics of the internal sequence, and resulting in conglomerate reservoirs Short-term sequence division is very difficult. Based on high-resolution sequence stratigraphy, by using comprehensively the contact relations and sedimentary features of Sequence reflected by seismic, well logging and full-hole coring well data, Sequence boundary are identified and sequence are divided. This research divided the ying-4 segment into 2 long-term base-level cycles,4 mid-term base-level cycles and 11 short-term base-level cycles. The spatial patterns are built for guiding to sequence stratigraphic correlation through the region's geological features in this area and provide a feasible way for researching internally to the thick conglomerate sequence.The provenance region of Ying4 conglomerate reservoir is restudied in this research. There are two provenance in the research area,one is northwest,the another is southwest on the evidence of lithologic character, grain size plane distribution,paleo-physiography,sequence characteristic,plane facies sequence and seismicfacies which provides theory foundation for forecasting conglomerate body.Owing to the conglomerate reservoir with a single lithology, poor sorting , color similar , not obvious characteristics of bedding features, there is with great difficulties to distinction of the reservoir Lightfaces and Microfacies. on the base of elaborate core describing,five criterions are proposed according to the grain size, interstitial character, degree of sorting,the contact manner,gravelstone arrangement. The heavy conglomerate is divided into 9 type and 22 subtype litho facies which offer lithology foundation for systematically studying internal fine structure of heavy conglomerate. Characteristics of this area through the conglomerate and fine summary of comparative sedimentology studies to determine the thick layer of this area into a conglomerate because of the transition to the braided river delta, the shallow gravelly braided-type fan delta facies.In the study area Y4 conglomerate reservoirs type of space is very complex and includes. Through a large number of micro-analysis, the study area the main reservoir space type of native intergranular pores, solution holes, cracks and composite porosity. By using of discharge period, discharge ventage and distribution scope of organic acids, the dissolution pore distribution predicting is first proposed. Under the circumstances of a variety of logging parameters failure to respond to gas-bearing formation, the frequency attenuation characteristics gathers is used to forecasting a favorable gas-bearing zones. Through this research, the most favorable target area of gas-bearing area is ultimately given in order to provide a basis for tapping the potential to gas reservoirs.