Study On Distribution And Potential-tapping Of Remaining Oil In Reservoir With Heterogeneity Of Dongpuaoxian Huzhuangji Oilfield

The structure is complicated and it has a serious heterogeneous reservoir inHuzhuangji oilfield, and now the oilfield has been in medium-high water cutdevelopment period after more than twenty years. The paper studies the heterogeneitycharacteristics of the reservoir on the basis of reservoir fine description;it studies thechanging rules of reservoir after water injection through analyzing the indoor experimentand chemical test data of the cored wells before and after water injection. And the papersets up the relation model of start-up pressure grades,start-up pressure and reservoirproperty on the use of the difference layer's start-up pressure grades and start-up pressurein the study of indoor experiment data and development testing data;The combination ofstart-up pressure study and remaining oil distribution study increases the study methodsof remaining oil and the paper studies the distribution rules of remaining oil inHuzhuangji Oilfield with several methods, and puts forward potential-tapping methods ofremaining oil on the basis of the use of reference on successful experience of in andabroad the country.From the aspects of sedimentology and diagenic metamorphism, this study pointsout that low compositional maturity and low textural maturity is the inner cause offorming serious heterogeneity in the district;And adopting dense well pattern and closespacing forced injection-forced development make it more serious on heterogeneity;High permeability stripes in the reservoir which affects the development of oilfield somuch is the important cause of small volume of injection water and poor developmentresult. The result of indoor experiment analysis on reservoir after water injection showsthat: water injection development affects the reservoir permeability very much andincreasing permeability action happens in layer with medium-high permeability in somecases. And the higher the original permeability is, the stronger increasing permeabilityaction happens. The effects on microscope reservoir heterogeneity after water injectionmainly appears in the increase of big pore space and throat, the stronger of reservoirheterogeneity and the decline of oil- driving efficiency. The distribution rules ofremaining oil are mainly affected by structure and reservoir heterogeneity, and theimportant direction of potential- tapping of remaining oil is the remaining oil in thelayers. Indoor experiment on start-up pressure grades of medium-poor layers shows thatstart-up pressure grades exists in layers with medium-high permeability;If start-uppressure grades is high, and start-up pressure grades of layers with medium-highpermeability declines obviously;The ratio of start-up pressure grades appears an obviousinterval characteristics from layers with small permeability to layers with medium-highpermeability. The result of development test on medium-poor layers shows that, with theincrease of permeability, start-up pressure rises in general, but the rules between start-uppressure and permeability becomes worse;Besides permeability, the variation ofsedimentary facies,injection-development well space and well pit conditions of oil waterwells affect the test results of start-up pressure. In view of the distribution characteristicsof remaining oil of reservoir with serious heterogeneity, the methods of potential- tappingof remaining oil include adjustment of injection and development,adjustment of layersystem,application of technological methods of oil mining and well drilling or complexmethods.The features and innovations of the paper are mainly like followed: First, set up themathematical model between start-up pressure grades , start-up pressure andpermeability through the study on data of indoor experiment on start-up pressure gradesand field test on start-up pressure;Second, create a new method on remaining oil studyon the combination of start-up pressure and remaining oil study;Third, analyze thesubjective and objective elements of variation on reservoir after water-injection, studythe variation rules of the reservoir;Fourth, put forward the potential-tapping methods onthe basis of the study on distribution of remaining oil;Fifth, point out that complextechnological methods should be used on the potential-tapping of remaining oil inreservoir with serious heterogeneity.