Research And Application Of Pressure Transient Well Test Analysis Method For Shale Oil Reservior

Chinese shale oil reserves are very rich,which will play a very important role in my country’s energy field.The shale reservoir itself has complex physical properties and strong heterogeneity.In addition,due to the different scales of fracturing,the complex fracture network after fracturing is different.However,the current single multi-stage fracturing horizontal well model is difficult to meet the complexity of the fracture network of shale reservoirs,and lacks a systematic inversion method for unstable well testing for multi-stage fracturing horizontal wells in shale reservoirs.Therefore,different models need to be applied to different fracturing horizontal wells to form a set of shale oil unstable well testing inversion methods.Aiming at the seepage problem of multi-stage fracturing horizontal wells in shale oil,this thesis establishes a single-zone model(SRV model),a dual-zone model(inner dualouter single model,inner dual-outer dual model),and a four-zone composite model(homogeneous-Non-recharge model,dual medium-with recharge model)and applied analytical method to solve,and analyzed the double logarithmic pressure and pressure derivative characteristic curve and the influencing factors of the model.A multi-zone composite model of discrete natural fractures is established,and numerical methods are used to solve the problem.The influence of hydraulic secondary fractures formed by fracturing and natural fractures of shale reservoirs on the well test curve is studied.The research shows that the early stage of the SRV model is similar to the two-zone trilinear flow model in terms of flow segmentation and sensitivity effects,but in the channeling stage the curve falls off to a greater extent,and there is no outer-zone linear flow stage;the four-zone multilinear flow model The typical curve flow segments of the model correspond to the model partitions;the typical curve of the multi-linear recharge boundary model of the four-zone model is divided into two parts,the inner flow and the outer flow,with 9 stages.The results of the multi-zone composite model with fractures show that the hydraulic secondary fractures mainly affect the bilinear flow and linear flow stages of the curve,that is,the fluid flows in the hydraulic main fractures and the fracture network;natural fractures affect all stages of flow.On the basis of the established model,a systematic analysis method of shale oil unstable pressure well test is formed.First,the formation and wellbore parameters are explained by analytical models,and then a numerical model is established based on these parameters for further fitting and analysis.The unstable pressure well test analysis method of shale oil is applied,and the Chang 7shale oil in Changqing Oilfield is taken as an example to carry out an example application,which proves the accuracy and practicability of the method proposed in this thesis.