Reservoir Evaluation Of The Chang-2Member Of The Yanchang Formation In Jiyuan Area, Ordos Basin

Jiyuan Oilfield lies in middle western part of Shanbei Slope in Ordos Basin and the primary oil-bearing bed is Yanchang Formation. And development in recent years have achieved good results. In order to conducive to scientific and reasonable prediction of reservoir distribution, author studied the Chang-2member in the Jiyuan sandbody distribution of characteristics, micro-pore structure characteristics, Diagenesis on the effects of pore, and ultimate combinatied the deposition, diagenesis, micro-porosity of research results, forecasted reasonably the distribution of favorable reservoir.Through the pore observated, Log analysised, Particle size analysised and combined with background information on the regional deposition, determined the Chang-2member in the Jiyuan Ordos Basin Area deposited delta plate subfacies and body skeleton distributary channel was formed by deposition. Delta plate subfacies was divided into distributary Channel and diversion in the inter-Wan Microfacies plane.With casting sheet analysis, scanning electronic microscopy and the technical analysis of high-Pressure to analysis,it was also shown that the main types of pores are remnant intergranular pores and dissolved pores. The reservoirs are poor in pore throat distribution, complex instructure, small and asymmetry in throat showing heterogeneity. Taken as a whole, they are the typical low Porosity and Permeable reserviors.Analysised the reservoir rock characteristies and diagenesis of the characteristies of in-depth and meticulous.Studies have indicated that Chang-2member sandstone oil reservoir type feldspar lithic sandstone and feldspar lithic sandstone-based. Compaction, carbonate cementation of the pores have made the more serious damage. Dissolution properties of the reservoir have made some improvement, kaolinite cementation has made low level damage, chlorite cementation has made some improvement. The purpose of loor area is now in Phase A of diagenesis. The study was divided into four diagenetie facies, type of pore-lining chlorite cementation and dissolution was the best reservoir properties.By the laws of the Physical properties and pore distribution of quantitative analysis of the evolution of that, deposition mainly determines the development of original porosity, diagenesis mainly determines the porosity of the transformation of the original reservoir level and the extent of secondary porosity development.Integrated these researches with practical situation in Jiyuan area, the sandstone reservoirs are divided into four types. Ⅰ and Ⅱ—good and better reservoirs are occur in the Chang-2meandering river channel sandbars.The distribution of favorable reservoir is lies in the middle and the northern western, which provides the credibility geologygist for further exploration and exploitation in this area.