Prediction Of Formation Pressure By Water And Polymer Injection And Theoretical Study Of Pressure Relief By Stopping Injection

Xiaermen oilfield belongs to an old area of Henan oilfield and was put into production in 1997.Due to the perennial development of water injection or polymer injection and reservoir permeability,and good connectivity,the pressure coefficient of the target layer is high,forming a high-pressure section.Because the upper formation is loose,and bearing capacity is low,high pressure and easy to leak layer coexist in the wellbore.This is easy to occur in the drilling process of the risk of well control out of control.In order to solve such problems,it is planned to analyze the influence of various factors on formation pressure theoretically.And then to predict the pressure in the well area by combining with the actual data of the block,and to conduct optimization research on stop-injection and pressure-relief.So as to reduce the risks in the drilling process.First of all,using the mathematical model derived from the analytical formulas to get the calculation formula of formation pressure,and establish the theoretical model of water and polymer injection pressure.At the same time,according to the dimensionless,the theory chart of pressure radius is established.And then put the actual data into blocks to analyze the single factor's influence on the formation pressure after change.The conclusion is that formation pressure is inversely proportional to formation permeability,injection-production well spacing and polymer rheology,is proportional to the development of fixed number of year and the polymer viscosity.Then,the numerical simulation software is used to establish the theoretical model of one-injection-four-mining well group to tudy what the change rule is formation pressure with the single factor in the plane and the longitudinal.And also use the simulation data to establish the change chart of relief radius,and two theoretical chart to verify each other,and then guide the actual block.Finally,numerical simulation is carried out for the actual block.Pressure prediction is carried out on the basis of good historical fitting,including numerical simulation prediction and formula prediction,which are mutually verified.Then,the stop and relief treatment is carried out for the high-pressure stratum.The reduced value of the pressure coefficient under different stop time is calculated,and the curve of the change with stop time is made.According to the curve,the stop time under the desired pressure reducing range can be calculated.This process can be used as an exemplary process of pressure relief.