Difference Of Changxing Formation Reef Reservoirs Developed Along The Both Sides Of Kaijiang—Liangping Trough In Northeast Sichuan Basin

For Permian Changxing Formation reservoir on the Sichuan Basin, predecessors have done a lot of comprehensive research and made significant progress on sedimentary facies, lithofacies palaeogeography features, aspects, reservoir characteristics and reservoir conditions, but their research on micro—fine characterization phase is relatively small and not systematic. In this paper, by using modern petrology, sedimentology theory, sequence stratigraphy and reservoir geology, taking Changxing Formation platform edge of Northeast of Sichuan as the research object, detailed analysis on different profiles and outcrop Changxing biological development platform margin Reef and explanation on the different characteristics of reef development is made, then the mode for different areas of reef development is put forward.Through outcrop reef GR measurement, combined with drilling GR curves, researching on different regions and microfaciesof reef logging response characteristics and analyzing the log response differences, the recognition mode for different microfacies reservoir of reef is established. Then fine analysis of micro pore types and physical characteristics on margin and internal reef of Changxing platform is made, as well as in—depth study about difference of microfacies reservoir space and physical parameters of reefs on both sides of Kaijing —Liangping trough. Finally,by describing the main controlling factors of reef reservoir development, analysis on different microfacies characteristics of the reef evolution is made.Some major discoveries and results are made as follows:(1) Through analysis of sedimentary micro-facies of platform margin reefs along both sides of the troughs, the organic reef on the eastern side more development of which the reefs have more flat connectivity, and stronger dolomitize,and progrades into the trough, whereas the western single reefs have less regularit,organic reef is major of aggradation.(2) Differences between the organic reef reservoir on both sides are compared, which include types of reservoir rocks, amount of reservoir space, reservoir physical property, and the log response of the reservoir. It is covered that Yuanbai and Longgang of the western trough have a relatively decreasing property from reef flat, reef core to reef base, and a better permeability of the microfacies poroperm. The reef flat on the eastern reef has better property than the reef core and reef base. The performance for the organic reef reservoir characteristics in different regions is that reservoir physical property of east of the trough sedimentary micro-facies are better than west of the trough.(3) A systematical analysis is made on the factors reservoir development controlling of organic reef on both trough sides from. It is found that sedimentary facies form the basis for the organic reef reservoir on the platform margin, the diagenesis desids the developing quality of reservoir,and that the tectonic fracturing is both constructive and destructive to the reservoir. Dolomitization and dissolution play the biggest role in influencing the property of the reef’s reservoir physical property.(4)The dolomitize plays an evidently transforming role to reform the carbonate rocks reservoir of Changxing Formation.The dolomite have the highest level of crystallization,and have grain structure、biological skeleton hole、solution pores、intercrystalline pore,and have various reservoir condition. Dissolution can change pore types and pore structure of reservoir,increase porosity of reservoir.(5)There are obvious differences between the dolomitization degrees of diverse platform margins in trough. Those differences are manifested as following: the dolomitization of reef flat on the western side of trough is comparatively strong, and its rock types are grainstone, dolomite with relic structure and grain dolostone; the dolomitization of reef core is comparatively weak, and its rock type is mainly limestone; the lithology of reef base is based on micrite bioclast limestone, with micrite interstitial material between most grains. Meanwhile, the most common rock type of the reef flat on the eastern side of trough is Grain dolostone and the most common one of the reef core is dolomitize. The dolomitization of reef base is comparatively weak, mainly with lime-dolomite, dolomitic bioclasts limestone,and micrite interstitial material.