Research Of Flexible Particle Plugging Agent On Drilling Fluids

Lost circulation is always a worldwide difficult problem which is difficult to solve in the process of oil and gas exploration and development.The global oil industry cause huge economic losses due to lost circulation.In recent years,lots of lost circulation materials?LCM?and technical aspects of the research work have been made at home and abroad,but most LCM cannot at the same time has good deformability,swelling,temperature resistance,salt resistance and other properties,resulting in poor lost control and repeated leakage occurred.In order to solve the defects of these LCM,the flexible particle plugging agent for drilling fluid was developed.The plugging agent is designed from molecular structure.Through the orthogonal experiment and single factor experiment,a flexible particle plugging agent with a temperature resistance above 150?is developed.The plugging agent is more than 5 times the tensile strength before and after aging at 150?,and its water swelling ratio in salt water is more than 7 times,and it has better water swelling and toughness at high temperature.And at the same time,the water swelling of the plugging agent has a certain delay.Plugging experiment shows that the flexible particle plugging agent has good compatibility with drilling fluid.The matching between the particle size of the flexible particle plugging agent and the sand bed is studied to determine the optimum particle size of plugging agent.It is found that the plugging agent can bear a pressure of 8 MPa and has a strong bearing capacity when the pressure test is used to evaluate lost control.On the basis of the above research,the filter loss agents,shale inhibitors and lubricants were optimized,and a set of lost circulation prevention and control drilling fluid system were developed.Through the performance evaluation of the drilling fluid system,the experimental results are as follows:the drilling fluid system has better inhibition performance;the drilling fluid system has better performance of bentonite resistance which reaches 10%,and it has certain salt pollution resistance,anti pollution of NaCl up to 6%,and anti pollution of the CaCl₂ up to 1.5%;the lost circulation prevention and control drilling fluid has good performance,it can bear 8 MPa in 10-20 mesh sand bed and bear 9 MPa in 20-40 mesh sand bed.