Reservoir Study and Model Building-case Study of Oil Group Ⅱ of the Member1of Dongying Formation in North Laoyemiao Oil Field
|Keywords||Nanpu Sag Laoyemiao Oil Field sedimentary facies reservoircharacteristic reservoir model|
The Laoyemiao oil field is located at northwest of Nanpu Sag, main oil-bearing formations situated at Miaobei Ed1formation, it’s a positive second-order tectonic, which controlled over Xi’nanzhuang fault of northern border of the sag, also a rolling anticline structure in inherited development process. This paper guided by multidisciplinary theories of reservoir sedimentology, logging geology, petroleum geology and oil field geology, the main object of this research is oil group II which is the main oil-bearing formations in Ed1formation, with modern reservoir evaluation theory and correlation technique, based on analysis of a great deal of data of drilling, logging, cores analysis reports and physical property results of about250wells, combined with litho facies, logging facies and cast thin section analysis, a series of studies of oil group Ⅱ in Ed1formation of Dongying group have been carried, including stratigraphic division and correlation, sedimentary microfacies, distribution rules of reservoir sandbody, the characteristics of physical property, heterogeneity of the reservoir, during the course of the study, several results are as follows.Stratigraphy subdivision and correlation of oil formation for about86wells in study area have been made by looking for regional stratigraphy correlation key beds, adopting methods of cyclical control and depth references, consequently the top and bottom boundary of oil group Ⅱ in E1formation is truly taken. According to lithological characters and bed thickness, oil group Ⅱ is divided into13small layers,22connecting-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, paleontology and well logging, single well facies and profile facies have been analyzed associating with 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, reservoir of oil group Ⅱ is confirmed belong to fan delta plain and fan delta front facies sediments, several sedimentary microfacies can be identified:overwater distributary channel, backswamp, distributary interchannel, underwater distributary channel, channel mouth bar, bar between branches, etc. In which underwater distributary channel and channel mouth bar are the main sandy reservoir. The distribution characters of the plane sedimentary facies in different stratum are analogous approximately, all of which distributed from north to NE-trending, and have succession on a certain degree from bottom to top.Research indicates of oil group II in Ed1formation is mainly composed of lithic feldspathic sandstones, the lithologic characters of sandstone is argillaceous cement, loose and with low structure maturity. The interstitial material mainly is clay and carbonate cement. The clay content is2.0%to17.0%and5.05%in average, which consist of3.52%clay matrix in average. The carbonate content is0to28.0%and3.43%in average. The siderite cement content is0.99%in average. On physical property, the porosity is24.1%, and the permeability is306.6×10-3μm2in average, which shows the reservoir of medium permeability.With data of physical property and log interpretation, macroscopic heterogeneity of oil group II in Ed1formation was researched, especially interbed heterogeneity and areal heterogeneity. It is included that the reservoir has strong heterogeneity as a whole. The distribution of sandbody is controlled by sedimentary facies, their geometric shape presents longitudinal zonality or branching with direction of north to NE-trending, 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 matched to the sand body morphology, and the physical property in the north by east of the study area is better than that in the northeast, and that in thick sandstone place is good relatively.Ed1formation is a set of rapid accumulation fan delta front facies, reservoir had a quickly change in horizontality, and structure was complicated by fault, with strong heterogeneity. In a comprehensive usage of applied geology, seismic, logging, and dynamic production data, a3D model for geologic model is developed by means of stochastic simulation and PETREL, including sandbody framework model, structure model, facies model and attribute model, provided a high-efficiency method for development of oil field.