Studies And Application On A New Type Silicate Non-permeable Drilling Fluid

The formation damage reasons and the difficulties of drilling were found after the investigation of the field 5 wells data from 3 blocks in the middle Junggar Basin. The technical idea was proposed that the complex silicate drilling fluid and the optimized non-penetrable materials were utilized to improve the inhibition and form the non-penetrable cake in order to stabilize the wellbore and protect the reservoirs. The silicate drilling system was carried out which could provide the anti-sloughing, salt-resistance, clay-resistance, electrical stability, temperature tolerance and weighting properties, and the high performance complex silicate non-penetrable material CSNP-1 was also developed. Then, the formula of non-penetrable silicate drilling fluid system was formed, and the complementarity design of drilling fluid to Well Yong 9 was compiled. The test method of non-penetrable silicate drilling fluid was founded. The novel non-penetrable silicate drilling fluid system has display the high performances, including the invaded depth 3.6cm on the sand-bed under the pressure 7MPa, the highest tolerant temperature 150℃and the pressure bearing capacity of non-penetrable cake more than 12.6MPa.This drilling fluid was applied in 4318.00-5895.00m interval in well Yong 9, section 3. Several silicate drilling fluids technical difficulties solved good in this well. The applied depth and long intervals were created on Silicate fluids in China. Pipe sticking commonly occurred to 215.9mm sloughing well bore in complicated Tuguluqun holes section was solved. The average hole enlargement is 13.86%, which is reduced by 30.77%, 17.91% and 5.31% compared to Yong 1, Yong 2 and Yong 6 without using this fluid. The well bore quality is best in the section 3 this block.The drilling fluid performs good anti-sloughing, anti-sticking, cutting transmitting and lowest invasion. The formed-filed technology was reasonable and operational for drilling operation in No 3 block of Junggar Basin. The drilling fluid was one of the best suitable systems. It should be more applying values in the future.