Analysis Of The Fine Sedimentary Facies In Xingou Group,Qian Dongnan

This thesis is based on the the geological characteristics and exploration practice of Xingouzui in the Southeast. On the basis of former studies, we make full use of seismic, drilling and any other data, especially highlight the study of ancient tectonic features of oil and sand group, micro-faces and reservoir distribution, building the mode of structure, reservoir and hydrocarbon accumulation in the target zone, which providing the high technical basis for stable and high production. The detailed contents were as follows:1.A study on characteristics of texture and structure Extensive research had been earlily made for texture and structure characteristics in the Southeast of Qiandongnan, this paper is modified by the new seismic and drilling data, focusing on the research of structural styles of key structural belt and evolution features, making certain of ancient geomorphological features of Xingouzui.2. Distribution of sedimentary microfacies and features of evolution Through the guided research of the regional sedimentary facies, coring, According to the physical properties of rocks, sedimentary structures, logging facies marks and analysis of laboratory data,it is judged that it mainly developed delta-lacustrine depositional system in the Southeast of Qiandongnan. debris sources of the werea is relatively simple, mainly affected by the influence of northern source, North reservoir conditions is better than South, hydrocarbon generation conditions as well; the delta front of Hydrocarbon Generation subsidence in the north develop the long succession of ancient uplift and ancient slopes which were the main accumulate werea of oil and gas. The specific content will be discussed in the following aspects:a.Among the stratigraphic characteristics, the Xingouzui were divided into two sections, the lower segment of Xingouzui is the main source rock and the main target exploration in the depression, from top to bottom is divided into layers of cream, I oil and II oil group, mud compartment, III oil groups, the distribution of large cream layer and mud compartment were stable in the region, which is the Formula markered bed.b.The analysis of sedimentary facies from the source analysis, Microfacies characteristics、a single well facies, profile facies analysis, depositional system distribution characteristics and so on for elaborating.c.The study analyed the controlling factors of the depositional systems and sedimentary evolution.The distribution of depositional systems controlled by many factors, in continental rift basin, the effect of paleotopography and tectonic movement were especially obvious, paleostructurel construct the ancient geomorphological and landform in the process of basin formation and evolution which played a rule of obvious effect3.reservoir distribution and evaluation According to the study of sedimentary facies, on the basis of reservoir prediction making full use of drilling data, studies of reservoir distribution characteristics and evaluation was carried out.Reservoir source of Xingouzui lower segment in Qiandongnan werea were mainly from Hanshui in northwest and Hanchuan in the northeast.We take the characteristics of the delta front and shallow lake deposits for example, the leading sand body were underwater distributary channel of Delta front mouth bar、beach and bar of shallow lake, the continuity of sand distribution was not very good. By the influence of pre-existing fracture and and syndepositional faulting in Cretaceous, the sand body was significantly thicker in the downthrown side and was extended along the fault, the fracture played obvious effect on the distribution of sandstone.4.Enrichment law of oil and gas and control factors of reservoir The oil and gas reservoirs in Xingouzui Work werea were enriched in the favorable raw hydrocarbon synclinal margin of positive structural belt. The concentration degree of oil and gas in Vertical from high to low were ordinally new lower segment three-oil group, the two oil groups, first oil group. The distribution and acumulation rules of Oil and gas were:First, the oil and gas distribution and enrichment focus on the main hydrocarbon source rock and its surrounding; the mainstream of the oil and gas migration control the distribution and concentration of oil and gas, faults played an important role on controling the migration and accumulation.Third, belts of sedimentary facies control the distribution of reservoir which determined the concentration of oil and gas.