| Four Block,located in the central depression of Songliao basin district Fuyu-xinmu uplift westernmost dome of Xinli anticline in the central of Xinli oilfield. Development area is 10.18 square kilometers, geological reserves is 10,365,600 tons, recoverable reserves is 3,006,200 tons, calibration recovery is 29%. Reservoir characteristics is low permeability structure-lithologic reservoir,average permeability is 11.05 MD, average porosity is14.4%. The original formation pressure is 12.2MPa,saturation pressure 9.6 MPa. Development purposes layers were under the Cretaceous Quantou four reservoir and Quantou three sections of the upper patrt of Yangdachengzi reservoir, reservoir in the study area is mainly fine sandstone, sedimentary environment belongs to the river-deltaic deposition.Four Block was invested into totally development in 1984. In the early,300 meters away from the inverted nine-spot square pattern was used and wells array direction was North East 67.5 degrees. In 1997, injection patterns of water was adjusted to 134 meters the linear water, at the same time, in the water array, the higher water wells were reverse injected. In the years of 2004,2005, and 2008, the well array further infill adjustment, expanding edge and so on.Up to December of 2012, the total numbers of wells are 292, in which 199 oil wells,136 open wells and have an oil production of 42,700 tons a year, cumulative oil production of 20,064,000 tons, oil recovery rate of 0.41%, recovery of 19.36%, recovery of 66.7% in the extent of recoverable reserves, remaining recoverable reserves of oil production rate of 4.,27%, and average water cut of 74.79%. The total numbers of water injection wells are 93 and open wells 65. It have day water injection of 1430 cubic meters, the average single well injection of 22 m3,542,000m3 water injection in a year, cumulative injection of 99,116,000m3, monthly injection production ratio of 2.49, cumulative injection production ratio of 1.93, deposit water rate of 79.5% underground.Four Block scale production of oilfields since 1984, along with continues to in-depth development of oil fields, has now entered the "high-yield water, high extraction" stage and the situation of development are become enormous. With the increase of the dynamic and static data, the level of awareness is deepening and a variety of development issues is come to the fore. So we must to constantly adjust and improve the current existing research results. And the distributions of the remaining oil fields are extremely complex currently, at this point three-dimensional reservoir modeling of working area is necessary. Through the study area’s porosity, permeability and oil saturation to clarify the circumstances in which the distribution of remaining oil in order to guide the adjustment in the late development of oil field and to improve the recovery of residual oil.Under the guidance of sedimentology, high-resolution sequence stratigraphy, logging geology and geostatistics, on the observation of coring core, we can figure out the sand development situation,the type of sedimentary facies and development patterns and characteristics. Using the Fine monolayer partition and comparison method, we build a fine strata framework of the work area. According to the observation result of the core and log responses, we can confirm a criterion of lithology-electricity corresponding relationship, mode of litho logy-electricity transformation relation and mode of log facies. Then Interpretate manually for sedimentary facies of every well and every layer to make sure sedimentary facies distritution features.On the base of prior study, we can confirm the reservoir sand distribution in the space and build a 3D geological model by Petrel. Combining the sedimentary faces we can set up a sedimentary model. Using geostatistics and stochastic simulation, the porosity, permeability and oil saturation modes are built. They are under control of sedimentary faces, vacuate test on models are carried on. On combination of the late oil saturation, we can know the distribution of residual oil and profitable layer.After study the work area synthetically, we get such conclusions:1. Using the theory of high-resolution sequence stratigraphy and the principle of large to small sedimentary cycle and control by different levels, the large scale flooding layer is considered as a marker bed. That controls the sand group boundary. By making the coring well as standardized well, each layer’s boundary is set up. The Fuyu and Yangdachengzi reservoir is divided into 9 sand groups and 26 layers. On the base of layer study, we divide Fuyu reservoir into 35 single layers.2. According to the sedimentary study, there are delta front and delta plain in the area. Delta front is made up of river under water, levee under water, estuary dam, thin sand between river and branch bay. delta plain is made up of river, subaerial levee, crevasse splay and flood plain.3. On the base of sedimentary micro faces study and layer contrasted framework, the 3D geological model which is reasonable is built. After digitalize the 2D sedimentary micro faces’boundaries, the definitive sedimentary model is built.4. Under the control of sedimentary faces, the porosity, permeability and oil saturation 3D models are built.5. When it comes to test the model, we adopt the Comparison test method. Through comparing the profile with the old one which including all wells, we make a conclusion that the two profiles are nearly same and the model is reasonable and right. It is predictive well.6. After calculate the geological reserves, we know some layers’reserves are higher than other layers. They are5、8、9、13、14.16. The remaining oil is mainly concentrated in the interlayer development and close to the local department of river.Through this study, we set up a geological model which is match with the geologic situation and predict the distribution of residual oil. This offers an important evidence to the later development plan. |
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