The Study On The Sedimentary Facies And Resvior Evalu-Ation Of Middle And Inferior Of Second Hetao In Northern Weigang Oilfield Of Nanyang Sag

Nanyang sag is a secondary tectonic unit in Nanxiang basin, about3600km2in area. Petroleum geological survey of Nanyang depression began in1958, and the petroleum geology research were done mainly in the80’s of the last century. Since the development of the petroleum geological exploration, the accumulated proven geological reserves has been more than1.6×107t. The study area is located in the northern area of Weigang oilfield in Nanyang sag, including Guan Zhuang area and the western margin of Baiqiu area, which is an area of78square kilometers.The reservoir is mainly controlled by the north east of Jinhua-Zhangdian delta sand,and the reservoir quality is good. Although there is a lot of study about hydrocarbon reservoir forming charateristics of Nanyang sag area,there are still the following problems needed further research, such as (1) the stratigraphic division degree is low, layer division results are not unified;(2) reservoir sedimentary facies, especially sedimentary micro facies needs further study. At present,because the coring is little, which has an obvious effect to these dimentary micro facies and facies analysis, and the current distribution of all kinds of sedimentary microfacies have been difficult to meet the demand for rolling exploration stage of work, which will affect the distribution of the reservoir. In order to understand the reservoir characteristics in the North of Wei Gang Oilfield in Nan-yang sag, we had four steps. First of all, using the theory of modern sedimentology, logging geology, seismic stratigraphy, high-resolution sequence stratigraphy is to unify the division of Baiqiu and Weigang. Secondly, according to the drilling core data, established the sediment coring well phase model; and the analysis were compared and the observation of core facies and logging data and established relation between various sedimentary facies and electricity phase, which is the logging facies model. At the same time, applied logging facies model of single well layer for the study area (the single sand body) logging microfacies, and analysi-ed sedimentary facies evolution of single well vertical. Then, distributed the reservoir on themain oil-bearing formation in study area, the reservoir area is divided into5categories; prediction of favorable reservoir size, thickness, lateral variation analysis, reservoir character, make small floor plan; porosity and permeability have been drilling, analysis the characteristics of the reservoir,prediction the favorable facies belt. Finally, by using3D seismic interpretation and reservoir research, superimposed existing structural interpretation results, mainly found structure of lithology complex trap. With the hydrocarbon accumulation dynamics theory, combined with the comprehensive evaluation of trap and reservoir results, optimizing targets, put forward the suggestion. Through a series of work, has the following several points:(1) H22was eventually divided into14layers, H23was eventually divided into12small layers;(2) identified, the sedimentary microfacies include distributary ch-annel, mouth bar, distributary Bay, far sandbar, delta front sheet sand, mud and beach bar in the study area;(3) the changes of H22and H23from the bottom to the top of the lake level is drop rise drop, so the sedimentary sequence isprograd ational-retrogradation and progradation;(4) The reservoir is divided into5types,a nd underwater distributary channel and beach bar belonging to theclass I reservoir.