Pressure Transient Analysis Of Multi-well System In X Block

Since the X block oilfield was put into development,it has undergone natural flowing,waterfloooding development,and encryption adjustment of the well network,making the entire block reservoir a multi-well system composed of water wells and oil wells.When analyzing the pressure transient of this block,most of them use the pressure after shut-in to evaluate the pressure of this block,but the pressure cannot accurately evaluate the pressure level of this block.Moreover,the well test data of the test well is easily affected by the adjacent well,and the well test curve will deviate significantly from the horizontal line in the later stage,that is,the characteristics of "up" or "down" appear,but the conventional single well test analysis method does not consider influence of injection and production of adjacent wells in a multi-well system.When analyzing the characteristics of the well test curve,this phenomenon is often interpreted as a boundary effect,and the pressure dynamic level of the block cannot be correctly analyzed,so the research of pressure transient analysis in multi-well systems is of great significance.Based on the theory of transient flow,this paper establishes a mathematical model of transient well test considering the influence of adjacent wells in a multi-well system,and the Galerkin finite element method is used to solve the mathematical model.The typical well test curves of homogeneous reservoirs and composite reservoirs considering the injection and production of adjacent wells in the multi-well system are drawn,and the sensitivity of the typical test well curves is analyzed,including injection-production ratio,permeability,and injection-production well distance and other factors.Established a multi-well system to calculate the pressure dynamics of homogeneous and composite reservoirs considering the effects of injection-production ratios,and analyzed the factors affecting formation pressure in homogeneous and composite reservoirs,including injection-production ratios,production and permeability and so on.At the same time,a set of numerical well test interpretation methods suitable for the transient well test theory model of the multi-well system was established,which laid a theoretical foundation for the well test interpretation of the multi-well system in X block.It is found through research that different parameters in the multi-well system have different effects on the well test curve.Different injection and production conditions of adjacent wells mainly affect the later stage of the well test curve.When the injection-production ratio is greater than 1,the well test curve in the interference stage shows up,and the larger the injection-production ratio,the greater the up amplitude.At this time,the more energy injected into the injection well,the stronger the bottom hole pressure recovery ability of the test well;When the injection-production ratio is less than 1,the well test curve in the interference stage shows a drop,and the smaller the injection-production ratio,the greater the drop-down,which is caused by insufficient formation energy supply;when the injection-production ratio approaches 1,the longer the radial flow duration.For homogeneous reservoir pressure dynamics,when the bottom hole pressure is constant and other parameters remain unchanged,the boundary pressure and average pressure of the production well are increasing as the injection-production ratio increases.The difference between the boundary pressure and the bottom hole pressure,and the difference between the average pressure and the bottom hole pressure are also increasing.The difference in fluidity ratio between the internal and external zones is the main difference between a composite reservoir and a homogeneous reservoir.The fluidity ratio mainly affects the fluid flow in the external zone of a composite reservoir.When the bottom hole pressure is constant,the smaller the fluidity ratio,that is,the worse the flow properties in the external zone,the greater the energy consumption of the formation,and the larger the boundary pressure and average pressure of the single well control range required.Finally,the numerical well test interpretation method of multi-well system is given.Using the established multi-well system well test theory model,the well of X block is tested and interpreted,and the X block is analyzed according to the established multi-well system pressure calculation method which provides an effective method for correctly understanding the pressure dynamics of block X.