Hydcocarbon Enrichment Regularity Of Chang6in Qilicun Oilfield Of Ordos Basin

QiLiCun Oilfield is located in Yanchang Country Shaanxi province. Tectonic location in the southeast of shanbei slope in ordos basin, the study area is located in the south of QiLiCun oilfield is the most developed recently for the oilfield blocks, exploratory well information is complete, the area is14.26km2. Since the area into development, the initial effects were better. However, in the lack of knowledge of geology and distribution features of hydrocarbon, the further oil and gas exploration and development has been seriously restricted. This paper subdivided Chang6formation and analysised features and rules of hydcocarbon accumulation and enrichment, it has important reality instruction significance in developing rational exploration and increasing development benefits.Taking the disciplines and theories of petroleum geology, sedimentology, petrology and reservoir geology as the guideline, and on the basis of abundant data and materials from drilling, logging, core, testing, producing analysis and research report, and widely gathering related data of neighboring region, this paper comprehensively studies the structural feature, sedimentary facies, reservoir rock, reservoir type and characteristics and hydrocarbon accumulation rules of Chang2reservoirs in study area.The results show that the study area is a broad gental west-dip monocline, with nose like structure locally. The deposition system of Chang6member is the Delta front deposition. Underwater distributary channel is the advantage facies in study area, it distributes nearly N-S banded, River mouth dam is less development. Rock types of Chang6reservoirs are mainly Gray, light gray, celadon in fine-fine arkose. The main diagenesis of reservoir sandstone are compaction and denudation, etc, the pore types are mainly intergranular and dissoluted ones, which belongs to very low permeability layer. Oil of Chang6reservoir here is the light weight oil with low viscosity, it has the good fluidity. Chang6reservoir is typical lithologic reservoir of elastic-dissolved gas drive.Through the detailed analysis of the hydrocarbon accumulation conditions, the final result shows that the accumulation and distribution of hydrocarbon in Chang6reservoir in QiLiCun Oilfield Chang6reservior is controlled by sedimentary facies, good reservoir, regional cap rock, structural nose, and so on. Among them, the structural nose has an inferior influence on hydrocarbon accumulation. The favorable hydrocarbon accumulation zones are the placewhere each factors match well.