Study on Plugging Micro-fracture of Shale by Using High Temperature Emulsified Bitumen

In view of the complex situation of the development of micro-fractures in the formation of high temperature deep wells, the large amount of drilling fluid filtration, which often causes the formation wall instability due to water absorption and expansion, the plugging technology of micro-fractures in the formation with high temperature emulsified asphalt is studied. Increase the softening point of asphalt in emulsified asphalt by adding phenolic resin and curing agent; The matching relationship between mudstone crack distribution and emulsified asphalt particle size was studied by scanning electron microscope, the performance of high-temperature emulsified asphalt added to drilling fluid is tested. The results show that when 4% phenolic resin is added to the emulsified asphalt, the softening point of the asphalt increases to 136 ℃; The particle size distribution of high-temperature emulsified asphalt ranges from 0 to 200 µm, with an average particle size of 1.18 μm. Conforming to the distribution law of natural fracture size of mudstone; When 4% high-temperature emulsified asphalt is added to the drilling fluid, the viscosity of the drilling fluid increases from 31 mPa.s to 37 mPa.s, the API filtration rate decreases from 25.8 ml to 17.6 ml, the extreme pressure lubrication coefficient decreases by 13%, the expansion coefficient of mudstone decreases by 20%, and the mud cake formed is more dense. By adding phenolic resin and curing agent into emulsified asphalt to improve the softening point of emulsified asphalt, the problem that emulsified asphalt cannot be used in high temperature deep wells is solved, and the application range of emulsified asphalt is expanded.