Reservoir Characteristics And Reservoir-forming Condition Of Bedrock Buried Hill In Beizhong Sub-depression

Beier Depression is a two-level structure in Hailaer Basin, Beizhong Sub-depression isin the south of Beier Depression, which is a "small and fat" oil-rich sub-depression of BeierDepression. As people increasingly attention to the buried hill, it has been noted that theexploration of buried hill reservoir in sub-depression. But because of the restriction ofgeological conditions and reservoir-forming conditions, exploration and development in theBeizhong sub-depression was been restricted. In this thesis, we use seismic, logging, welllogging, rock, production tests, and other geological information to study the reservoircharacteristics and forming conditions of bedrock buried hill, thus make a comprehensiveevaluation of the reservoir to predict the favorable reservoir.The rock types of bedrock buried hill in Beizhong Sub-depression mainly include tuffand andesite, and a small amount of tuff, mudstone, tuffaceous sandy conglomerate, generalglutenite, etc. The lithology of clastic reservoir rocks mainly contains feldspathic litharenite, ithas lower maturity of composition and textural maturity. Reservoir property of bedrock buriedhill in Beizhong sub-depression is ultra low-porosity low-permeability and low-porositylow-permeability. It has characterized by abnormal development of high porosity zone in thevertical. Affected by the formation of deep cracks, in deep geological formation, the situationthat low porosity permeability benefit to the development of oil and gas. There are three typesof reservoir space in study area: elegance shower filter-porosity, crack, solution vug, and themain reservoir space is the crack. Diagenesis in bedrock buried hill mainly includescompaction, cementation, metasomatism, and dissolution. Divide the stage of the diagenesis,the diagenetic stage in study area is the late diagenetic stage, a small part is in the middlediagenetic stage B. There are two types of diagenetic facie: cracks phase and compactioncementation phase.In this paper, we use the weight coefficient method to make a comprehensive evaluationof bedrock buried hill in Beizhong sub-depression, we judge that the reservoir of bedrockburied hill in Beizhong sub-depression is mainlyⅠ,Ⅱ reservoir, and the type ofⅠ reservoirlocated near the well of Xi4.Through the division of the buried hill type, Beizhongsub-depression belongs to the syngenetic uplift buried hill of syngenetic buried hill. Torecover the ancient geomorphological, Beizhong Sub-depression is higher in the terrain. Thisarticle describes the reservior-forming conditions in Beizhong sub-depression from thehydrocarbon source rock, cap rock, traps, reservoirs, divert system, get the main controlling factors of hydrocarbon accumulation: hydrocarbon generation condition, divert system,effective crack and hole.Fault uplift zone is the most favorable for oil and gas explorationarea.