Research On Gas Reservoir Of Yanchang Oil Field Of The Lower Paleozoic In Ordos Basin

Throughout the Paleozoic of the present situation of oil and gas exploration in Ordos Basin, we discovered that lower Paleozoic carbonate reservoir have a very large potential to found more oil and gas reservoirs and that located in the upper part of the ancient Ordovician of karst weathering crust is one of the beneficial reservoir. The thesis aims at the practical demand of the Paleozoic oil and gas exploration of Yanchang Oilfield..Based on the analysis of regional data and Drilling, logging, coring, laboratory analysis, thin section analysis, etc. and multi-disciplinary knowledge of geological theory, We have done extensive reservoir research on carbonate reservoir characteristics and controlling factors of Majiagou 5 member of study areaMost wells drilled Majiagou 55 sub-member and some have Majiagou 6 member, which is a product of restricted platform-tidal flat facies of high-water carbonate deposition model is a regional gas-bearing, developing a gray floor, clouds flat, mud flat clouds, clouds with cream floor and other microfacies.The gypsodolomite facies of Majiagou 541,522and 513 is favorable sedimentary facies in this area.Pores, caves and cracks is the main reservoir space of Majiagou 5 carbonate reservoir,which superimposed on each other and show a strong heterogeneity.In addition, under the influence of factors such as tectonic evolution, reservoir distribution showed some differences on the spatial.Weathering crust,located vadose zone slope have a better reservoir performance,which is the most favorable reservoir development zone.In this area, there developed good source rocks, which is the coal measure strata of Carboniferous-Permian and marine limestone, argillaceous limestone, mudstone and coal of ordovician-permian, and capping formation which is the lake-based shale of Shihezi and Shiqianfeng, the mudstone of the bottom of Benxi, Taiyuan and Shanxi,and dense limestone, argillaceous dolomite, gypsum layer of Ordovician.Those provides better conditions for the formation of natural gas pool.