Reservoir Of Comprehensive Evaluation On Chang 2 In Chuandao Region Of Xiasiwan Oilfield

Chuandao region of Xiasiwan oilfield locates in south-central of Shanbei flank belt in Ordos basin covering an area of 70 km. Chang 2 oil layer of late Triassic is an even slope uplifting from west to east gradually and locally developed low relief nose uplift structure. This article focuses on how to determine lithologic traps and development areas with good porosity and permeability so as to fully use core, well logging and abundant of static and dynamic data and reservoir geology, reservoir sedimentology, reservoir well logging theory to research micro sedimentary facies for Chang 2 oil layer, summarizes controlling factors of sandbody distribution, analyzes preserving capability of the reservoir and finally predicts favorable geologic target which provide geologic basic for next exploration deployment. Main understandings for Chang 2 oil layer of Chuandao region.(1) According to the principle of stratigraphic correlation, Chang 2 oil layer of Chuandao region of Xiasiwan oilfield would be separated into three oil sub-layer which including Chang 21,22,23.The key oil-bearing formation Chang 22 was further divided for Chang 221,222,223 by Sedimentary cycle.(2) It is delta sedimentary environments controlled by northeast sources. Sub facies of delta is developed. It will union area geology background, distinguishes out three kinds of micro sedimentary facies including subsea distributary channel, subsea distributary channel flank and interdistributary bay. The subsea distributary channel is mainly reservoirs in study area.(3) Mainly fine sandstone and coarse siltstone, low maturity for component and medium maturity for texture. Total thickness of sandstone is 17.6-46.8m, which spreads from northeast to southwest like banding is controlled by micro facies of subsea distributary channel in delta system.(4) Porosity types of the reservoinpredominantly intergranular pore,secondly innerg ranular corrosion pore and locally developed fissure which weak porous structure.Diage nesis types:mainly compaction, cementation and dissolution. Nowadays it is a period o f time A,terminal diagenesis for Chang 2 oil layer.(5) 3 types of reservoirs:I(good),II(medium)and III(bad).Lithology is pure forâ… and â…¡,mainlyfine sandstone;mainly siltstone and lime and mud cemented fine sandstone,generally oil-poor.