纳米二氧化硅复合聚合物凝胶的制备与堵漏性能OA北大核心

Gel lost circulation materials(LCMs)presently in use have several shortcomings such as low strength,poor toughness and uncontrollable gelling time etc.A high gel strength composite nanomaterial and polymer gel LCM has been developed to overcome these shortcomings.The composite nanomaterial and polymer gel LCM is synthesized through physical-chemical crosslinking reaction with raw materials such as polyacrylamide(PAM)as the main gelling agents,nano silica as the strengthening agent,sodium carboxymethylcellulose(Na-CMC)as the viscosifier and phenolic resin as the crosslinking agent.In laboratory experiment,the optimum conditions for preparing the composite gel LCM were determined and the gelling performance,swelling capacity and fracture plugging capability of the composite gel LCM evaluated.The crosslinking mechanisms and fracture plugging mechanisms of the composite gel LCM were also analyzed.It was found through the experiment that the best composite gel LCM can be obtained in the following reaction conditions:1.5%PAM,3%nano silica,0.6%Na-CMC,1.5%crosslinking agent and temperature for the crosslinking is 150℃.The composite gel LCM obtained in these conditions has gel strength of 1,000 Pa,gel viscosity of 6×105 mPa∙s and gelling time of 2 hours.This composite gel LCM has good swelling performance and can be used to plug fractures of different sizes.An LCM slurry formulated with the composite gel LCM and an inert material,after being used to plug fractures of 1-4 mm in width,formed an LCM barrier across the fractures with pressure bearing capacity of 12 MPa(measured at 150℃and after aging 48 hours).The composite gel LCM is easy to manufacture and cost effective,and can hopefully be used to solve severe mud loss problem encountered in drilling highly porous and fractured formations.