Research The Fine Characterization And The Distribution Law Of Sand Bodies Between He8Section And Shanl Section Of Block Su48

This paper is on the basis of previous studies, the integrated use of Sedimentology, Reservoir Geology and the new theory and method of exploration activity. Learn from the latest research achievements of the He8interval and the Shanl interval in the Sulige Gas Field. By drilling cores and outcrop observation, sample analysis, log interpretation and other means, system research the reservoir sand of the He8interval and the Shanl interval in Su48block,the western of Sulige Gas Field with the main line to the regional tectonic-sedimentary environment-sand body distribution-reservoir prediction. Obtain the following results and understanding:Su48block stratum structure is relatively simple that two marker bed could accurately dividing Shihezi and Shanxi Formation. The bottom of the Shiqianfeng Formation develops purple pebbled coarse sandstone. Because mudstone and smaller sandstone developed at the top of Shihezi Formation, coarse sandstone at the bottom of Shiqianfeng Formation has high resistivity, but mudstone and smaller sandstone at the top of the Shihezi formation has low resistivity, so that resistivity curve movement presents A step down. The second is that Taiyuan group develops ash black mudstone, siltstone, coal rocks mix with white fine-coarse sandstone. According to the three auxiliary layer mainly produced gas formation He8and Shanl formation can be divided. The three auxiliary layer:sandstone locally developed at the bottom of He7segment, camel neck sandstone developed at the bottom of He8segment, iron ditch sandstone developed at the bottom of the Shanl segment.The major source of purpose formation in the study area layers is quartz-rich parent rocks from Middle Proterozoic boundary, the west of Yinshan ancient land where located on northern of Ordos Basin. Controlled by source direction and basin structure, developed in the area was the north-south trending fluvial-deltaic depositional system. The sedimentary facies analysis showed that Shanl formation of Shanxi group in this area developed meandering river facies. Development of sedimentary subfacies have the River subfacies, River flood subfacies and Embankment subfacies. The riverbed stranded, Interchannel bay, River flood swamp and point bar are the most major micro-combined in purpose intervals. The down part of He8formation develops braided river deposits. Development of sedimentary subfacies has River subfacies and Embankment subfacies. sedimentary microfacies has underwater distributary channel microfacies, levee the microfacies and point bat. With the rivers during the He8 formation, the deposition from early to late gradually weakened. The sedimentary facies of He8sub-section evolve into the meandering river facies. Development of sedimentary subfacies have the River subfacies, River flood subfacies and Embankment subfacies. sedimentary microfacies has underwater distributary channel microfacies, phase of levee micro, point microfacies relatively not developed.Due to the a fluvial delta multi-phase development, frequent multi-phase riverbed subphase stacked increase the thickness of sand bodies, and also increases the instability of effective sand bodies. The sand bodies stacked in different ways with different stratigraphic units, shown in that the sand body of He8sub-section is isolated, the sand body of He8down-section is cut stacked and stacked, the sand body of Shanl section is isolated type and stacking. Among the single layer of sand develop mudstone interlayer or deterioration porosity permeability sandstone sandwich because of cementation. Stratigraphic units of He8sub-section and Shanl section show to "mud pack sand" phenomenon. Stratigraphic units of the He8down-section is rendered as "sand bags mud" phenomenon.Lithologic gas reservoirs in the study area reservoir performance is strongly influenced by diagenesis. Among them, the destruction to the primary porosity rock is compaction and cementation. The stratigraphic units of Shanl segment and He8segment depth between3200-3700m, the overlying water and sediments of the pore space of the objective interval and the total volume of the transformation is quite strong. Cementation reduces the primary pore space and permeability of the sand bodies. The stratigraphic units of Shanl segment has siliceous, kaolinite, chlorite and siderite combination-based, The stratigraphic units of He8segment has siliceous, chlorite and calcite. cementation was relatively developed. Metasomatic alteration, dissolution and cataclasis had structure constructive to the rock pore. Due to the compaction of the Stratigraphic units of the He8down-section is feeble, the primary pore space is saved. The denudation is strong, the secondary dissolution pore space connected isolated pore space, Reservoir sand body porosity and permeability values are relatively high.In He8segment Shanl layers deposition, sand body distribution and effective sand body distribution analysis, based on the reservoir properties, respectively divided reservoir sand body of He8sub-section and He8down-section and Shanl section in the study area into three levels for reservoir evaluation. Advantage reservoir of the Su48block is in the He8sub-section, followed by the He8down-section, the reservoir of Shanl section is worst. Scattered distribution is the main reason. The He8sub-section is given priority to with Ⅱ type reservoir, Ⅰ reservoir accounts for about20%. The reservoir of He8down-section is mainly Ⅱ reservoir and Ⅲ reservoir, Shan1section is given priority to with Ⅲ type reservoir. The piont bat microfacies of He8down-section is the best form sedimentary environment effective reservoir facies, controlled the reservoir of He8down-section.