Performance Evaluation And Parameter Optimization Of WK Long-acting Particles Profile Control System

WK long-acting particle is a newly developed particle profile control agent in oil field.It is made of styrene butadiene rubber material.Compared with gel and expansion particles,it has advantages of strong tensile strength,strong compressive resistance,strong salt resistance,strong thermal stability and strong shear resistance.In principle,the WK long-acting particle enhances the deformation capacity,improves the sealing strength of fractures,and extends the effective period of products.Thus WK particle has three advantages of "getting in,blocking up and lasting effect”.Aiming at the problem that WK long-acting particle is not effective in field using,the laboratory research is carried out.Suggestions for improving the properties and using methods are given.Visual particle injection experiments are carried out using transparent glass model to study the carrying capacity of polymer solutions with different viscosities to WK particle system.It is suggested that viscosities of polymer should range from 5.0 to 11.3 mPa·S.Fracture matching experiments of different sizes of long-acting particle are carried out,and the matching relationship between particles and fractures is given.It is suggested that the compressive deformation ability of particles should be further enhanced.It is suggested that the strength of particle should be increased to more than 1.0N and the resilience coefficient of particles should be increased to more than 80% under 8 MPa pressure.The profile control and oil displacement performances of various combination systems of profile control particles are studied.The parameters such as particle size distribution,injection mode and slug size are optimized according to the product standards of corresponding construction blocks.The recovery factor can be increased by more than 2% on the original basis,and the optimized product standards corresponding to three blocks are given.Based on the single pipe fracture model seepage experiment,the best profile control system called "equal proportion mixed particle + expansion particle + weak gel" is selected.According to the actual situation of the reservoir,two-pipe parallel flooding experiment is carried out.Through changing the slug size,injection mode and particle size distribution of the profile control system,parallel contrast experiments are carried out.The profile control system with the best effect of enhancing oil recovery in each core experiment is selected as the optimization standard of the corresponding blocks.Combining the field test parameters and the actual geological conditions of three blocks,the field test parameters of three blocks are optimized.The conclusions obtained in this paper have certain reference and guiding significance for the using of WK long-acting particle profile control agent in the field.