The Research Of Production Dynamic Rule In Tight Oil Reservoir

Tight oil resources are abundant all over the world,in the case of conventional oil and gas exploration and development degree is generally high,the North American tight oil realized the industrial production by the "horizontal well and volume-fracturing" unconventional development technology,changed the pattern of world energy,tight oil has become an important succeed field of oil and gas development in the future.Although tight oil resources are rich in our country,there are still no examples of successful development,the tight oil development as a whole is still in the locally pilot test stage.Due to the complex geological conditions,poor physical property,strong seepage resistance in tight oil reservoirs,there are basically no natural production.Horizontal well volume fracturing causes the heterogeneity of reservoir pore space becomes stronger,the flow mechanism of different scale media is complex,lack the dynamic prediction model that can reflect characteristics of tight oil reservoirs,single well production forecasting is difficult and the well production performance rule is difficult to grasp.Therefore,there is an urgent need to start from mechanism research and the research of tight oil reservoir production dynamic rule has important theoretical and guiding significance to determine the tight oil development technology policy.Reservoir engineering method and the numerical simulation technology are applied,this paper has a comprehensive research about tight reservoir characteristics,seepage mechanism,production performance and the dynamic prediction model of horizontal well volume fracturing in tight oil reservoir,the main research results are as follows:Clarified the mm-micron-nanometer scales pore fracture system development characteristics of tight oil reservoir,micron and nanometer scale pore is given priority to,there are different scale cracks such as:Nano-cracks,micro-cracks,local and regional cracks;Reveals the oil in the tight reservoir are continuity contained from big pore to nanometer pore.Lay a foundation for the research of the seepage mechanism laws and production performance.Reveal nonlinear seepage mechanism of tight oil reservoirs.When permeability is less than 0.01mD,matrix stress sensitivity is weak,crack has critical closure pressure,at the same time the tight reservoir has high start-up pressure gradient.Build the mathematical description model of matrix and fracture pressure sensitive effect and start-up pressure gradient,provide theoretical support for the tight oil development dynamic and the evaluation of the capacity.Matrix and fracture's contribution to the production during different production stages of tight oil reservoirs are clarified.Initially the high production and rapid declining stage is mainly contributed by the fracture,low production and stable stage later is mainly contributed by the matrix.Find out that power exponential decline method can more accurately describe the production decline rule.The evaluation of the well dynamic recovery and Estimated Ultimate Recovery(EUR)laid the material foundation for the productivity prediction.Based on the non-linear seepage mechanism of the tight oil reservoir,build the dynamic prediction model of horizontal well volume fracturing in tight oil reservoir.Find out the main factors that affect fracturing horizontal well production:the number of segments,fracture length and flow conductivity though the parameter sensitivity analysis of horizontal well volume fracturing in tight oil reservoir.Increase the size of the volume fracturing can enlarge the control volume and greatly improve the single well production.Provide a theoretical and technical support for scientific,reasonable and efficient development of tight oil reservoir.