A Study On Low Fluctuation Pump By Using Hydraulic Filter

At present,the demand for oil and gas resources in the world is gradually increasing,and the focus of oil and gas reservoir development has gradually extended from the development of conventional oil and gas to the development of unconventional oil and gas.Therefore,the research on the seepage theory of staged fracturing horizontal wells in tight reservoirs has also become a hot spot.However,there is still a lack of understanding of the relevant seepage laws,which is one of the important problems in the development of tight oil reservoirs.The unstable seepage characteristics of tight reservoirs are based on the low-velocity non-Darcy seepage law,so the influence of starting pressure gradient cannot be ignored.In order to establish the seepage model of staged fracturing horizontal well in tight reservoir considering the starting pressure gradient and stress sensitivity effect,this paper firstly uses Laplace transform and perturbation transform to establish the point source function of tight reservoir considering the starting pressure gradient and stress sensitivity effect,and then uses the mirror principle to obtain the point source function under different boundary conditions.Then the above point source functions are integrated in different directions or ranges to obtain the basic source functions such as line source,surface source and plate source under different boundary conditions.Finally,by using Riemann integral,superposition principle and other mathematical solving methods,the unsteady seepage model of staged fracturing horizontal well considering start-up pressure gradient and stress sensitivity effect in tight reservoir is formed.Then,the MATLAB program is written by using Stehfest numerical inversion and Duhamel principle to solve the model,and the relevant production dynamic data of staged fracturing horizontal well are obtained.The results are compared with the commercial numerical simulation software CMG to verify the correctness of the model established in this paper.At the same time,the influence of wellbore storage coefficient,channeling coefficient and storage ratio on the relationship between pressure,pressure derivative and time is studied.Finally,data sensitivity analysis and well test interpretation are carried out.The results show that the model established in this paper can better simulate the seepage characteristics of staged fracturing horizontal wells in tight reservoirs,and make up for the shortcomings of the previous model in considering the dual factors of starting pressure gradient and stress sensitivity effect.After starting the pressure gradient,it mainly affects the later radial flow stage of the seepage stage,indicating that the exploitation of tight reservoirs needs to consume more energy.Compared with the early stage of the seepage stage,the stress sensitivity effect has a greater impact on the later stage of the seepage stage.With the increase of production time,the stress sensitivity effect will lead to the greater bottom hole pressure difference required by the oil well under the same production conditions.The seepage stage is divided by the seepage model,and the sensitivity analysis and evaluation of the key parameters are carried out.Based on the well test theoretical model established in this paper,the actual test well data of tight oil wells are interpreted and analyzed.The well test curve drawn from the actual test well data is fitted with the typical curve plate to obtain the parameters until a good coincidence degree is reached.According to the proportional relationship of coincidence points,the relevant physical parameters of reservoirs and wells can be obtained.The research results provide some theoretical support for the economic and efficient development of tight reservoirs in China.