Study On Water - In - Oil Emulsifier And Its Application In Oil - Based Drilling Fluid

Shale gas as a clean and environmentally friendly new energy, and its development and utilization has become a new bright spot in the global oil and gas exploration and development. Shale is widely distributed in our country, and has a huge potential for exploration and development. The shale gas resources are very rich, the total resources are up to100×1012m3, equivalent to twice the amount of conventional natural gas. Compared to water-based drilling fluid, W/O emulsion drilling fluid because its advantages like good lubricity, calcium salt intrusion, resistance to high temperature, conducive wellbore stability, and little damage on the production floor, has become important drilling fluid system of shale formation. Sichuan Basin as China’s shale gas mining demonstration area, its exploration and development is of great significance. However, in the process of using domestic W/O emulsion drilling fluid in the Sichuan Basin shale gas exploration drilling, they found that drilling fluid system for its emulsion stability and rheology are not stable enough, and plugging ability is not strong enough, there are some problems like block off and fragmentation of collapse when drilling the shale formations in Longmaxi and Qiongzhusi, and these problems bring huge economic losses to the construction unit.This paper mainly for the particular issue of oil-based drilling fluid system’s not so good emulsion stability, I will do in-depth and meticulous research for W/O emulsifier, and optimized high performance emulsifiers FY-9, the specific composition is:3.47%SP-80+0.53%TW-80+0.5%ABSCA+0.125%CN. In the preferred emulsifier experiment, the formula of base fluid is:340mL liquid diesel (0#)+8g CaO+60mL CaCl2solution (the concentration is20%). The emulsifying mechanism was analyzed with the results of the preferred emulsifier experiment, and verified from the interface tension, the strength of the interfacial film, the droplet size and distribution.On the basis of preferred emulsifiers out on the FY-9, and through testing the compatibility of organic soil, richmond agents, wetting agents and fluid loss agent, etc, I get the W/O drilling fluids system(1#) of good performance, and the formula is:300mL diesel (0#)+2.5%YJT-8+2.6%SP-80+0.4%TW-80+0.4%ABSCA+0.1%CN+2%CaO+3%JLS-3+0.4%TQJ-3+53mL CaCl2solution (the concentration is20%)+1.5%RSJ-2+900g barite. The density of1#W/O emulsion drilling fluid is2.18g/cm3, the API filtration rate is less than1ml, the HTHP filtration rate is less than2ml, the ES is more than600V, and it has high temperature and pressure rheology, and it also has plugging ability. Add3%of the sealer FDJ to the1#to get the2#W/O emulsion drilling fluid, and the performance of2#is better, fully meet the needs of the Sichuan Basin shale gas drilling.