Study and Application of Latex Particle Plugging Agent

In the development of oil and gas fields, the failure of pressure test caused by wellbore leakage seriously affects the construction progress, and the annular pressure also brings a severe problem to the safety production, so it is necessary to restore the integrity of wellbores by plugging construction. In this paper, a kind of latex particle plugging agent is prepared based on the reverse emulsion dispersion principle, which can effectively seal micro-leakage and eliminate the drilling and grinding process. Latex particle plugging agent is a low viscosity aqueous solution system. During construction, latex particles with a size distribution from micron to millimeter scale enter into the leakage throat under pressure, under the effect of formation temperature and pressure, latex particles coalesced each other form colloid and block the fluid channel. The residual plugging agent in the tube is liquid, which can be directly discharged back from wellbores. The laboratory test results show that for the thread leakage with a pressure drop of 1.1 MPa/min at 22 MPa, the pressure drop in 30min is 0.56 MPa under 55 MPa after plugging, which conform to the wellbore pressure testing standards (<0.7 MPa). The field test is carried out in a natural gas vertical well, leakage point position in the range of 1141.89–1199.25 m, the testing pressure dropped from 20.0 MPa to 0 in 30 min initially. After plugging, the water pressure testing shows no pressure drop at 25 MPa within 30 min. The plugging agent is water-based solution, environmental friendly and low cost, which conducive to large-scale field use.