Research On Oil Deposit Characteristics And Remaining Oil Distribution In North Laoyemiao Region Of Oil Ⅱ Of The Member1of Dongying Formation In Laoyemiao Oilfield

Laoyemiao oil field is located in Tanghai, Luannan, Fengnan County, Tangshan City, Hebei Province, south by West14Km away from Tanghai County, south near Bohai bay. Location of the structure is in Nanpu Sag western of Huanghua depression northern, which is a forward two level structure controlled by northern border Xinanzhuang fracture, and inherited developed rolling anticline, whose tectonic belt area is about150Km2, devided into south Laoyemiao and north Laoyemiao,and in which the north Laoyemiao is the rolling anticline structure body.At present favorable show of gas and oil has been found in oil Ⅱ of the Member1of Dongying Formation in north Laoyemiao area, which has potential capacity for further exploitatin, but with weak research on remaining oil distribution. For the sake of deeply researching the rules of remaining oil distribution, it is necessary to carry a series of studies for oil Ⅱ of the Member1of Dongying Formation in north Laoyemiao area, including sedimentary facies, reservior characters, oil deposit characteristics and remaining oil distribution rule.Guided by multidisciplinary theories of reservoir sedimentology, logging geology, petroleum geology and oil field geology, based on analysis of a great deal of data of drilling, logging, cores analysis reports and physical property results of about80wells, combined with litho facies, logging facies and cast thin section analysis, a series of studies of oil Ⅱ of the Member1of Dongying Formation in north Laoyemiao area, Laoyemiao oil field have been carried, including stratigraphic division and correlation, sedimentary micro facies, distribution rules of reservior sandbody, the characteristics of physical property, heterogeneity of the reservoir. On above basis, the distribution characteristics of oil and petroleum accumulation control factors have been analyzed, and then the main reservoir types have been summarized,at last the remaining oil distribution rule has been analyzed and summarized. During the course of the study, several results are as follows.The top and bottom boundary of oil Ⅱ of the Member1of Dongying Formation is truly taken by making stratigraphy subdivision and correlation of oil formation for about80wells in study area, which are further divided into13small layers. At the above effort,14connecting-well sections of profile and cross is established for strata subdivision and correlation in order to control the all area.Based on the detailed stratigraphic correlation, combined with the facies signs of rock types and their characters, sedimentary textures and structures, and well logging, single well facies and profile facies of oil Ⅱ of the Member1of Dongying Formation have been analyzed associating wits lithofacies and logging facies, then the plane distribution characters and evolution of different member’s facies have been studied by constructing contour maps of sandstone thickness. Consequently, oil Ⅱ of the Member1of Dongying Formation is confirmed belong to fan-delta plain and fan-delta front sediments, containning sevaral sedimentary microfacies such as upper-river channel, interchannel, underwater distributary channel, bar between branches, mouth bar, in which underwater distributary channel and mouth bar are the main reservior sand. The distribution characters of the plane sedimentary facies in different stratum are analogous approximately, all of which distributed to northwest and northeast, and have succession on a certain degree from bottom to top.The research of reservoir characteristics indicates that the sandstones of oil Ⅱ of the Member1of Dongying Formation are lithin arkose sandstone and feldspthic lithic sandstone. The interstitial materials mainly are clay and carbonate cement, the content are between4%and12%, the average is9.4%, secondly is siderite cement, and the average is1.1%. On physical property, the porosity are mainly between9.2%and34.2%, the peak value are between20%and30%, the average is24.1%, and the permeability are mainly between0.1×10-3μm and4803×10-3μm, the average is332.8×10-3μm2, which shows tight reservoir characters of middle porosity and middle permeability, and the physical property of different stratum presents fine trend from bottom to top.With datas of physical property and log interpretation, macroscopic heterogeneity of oil Ⅱ of the Member1of Dongying Formation has been researched. It is included that oil Ⅱ of the Member1of Dongying Formation reservior has strong in-layer heterogeneity, middle to weak interlayer heterogeneity and strong planar heterogeneity. The geometric shape presents longitudinal zonality with direction of northeast to southwest and northwest to southeast, and sand thickness vary unequally. The sandbody communication along the source direction is good, but perpendicular to the source direction is bad. The distribution of physical property on plane is basically mached to the sand body morphology, and The physical property in the middle and south of the study area is better than that in the north, and that in thick sandstone place is good relatively.The distribution characters of oli and gas of oil II of the Member1of Dongying Formation have been analysed with datas of logging and well testing reports. The results suggest that on plane the distribution range of hydrocarbon is wide, but dispersive and being a small scale. Its is mainly concentrated on the two sides of the F4fault. On profile the hydrocarbon distributes in all small layers, longer oil-bearing intervals, viscous crude distribution of oil and gas layers.According to comprehensive researchment above and analysing existing hydrocarbon reservoirs, it is included that petroleum reserviors of target stratum are mainly and structural-lithologic hydrocarbon reservoirs, structural hydrocarbon reservoirs and lithologic hydrocarbon reservoirs. Hydrocarbon reservior are mainly controlled by multiple factors such as sedimentary microfacies, permeable sandbody, microtectonics, among which, the favorable facies belt and the permeable sand body are the main controlling factors, the next is the microtectonics, thus favorable sedimentary facies distribution and permeability of sand is an ideal target area for exploration.Based on the analysis of controlling factors of remaining oil, influence factors of distribution of remaining oil, in addition to reservoir sedimentary facies and lithology, physical property, heterogeneity, structure and sand body distribution outside the influence, are also closely related to the reservoir type and mining methods.