Research and Application of Strong Restraining and Plugging Polyamines Drilling Fluid System

When the wells were drilled in and under the formation of the west hill YAO groups in South Bao block,many complicated troubles occurred due to too low density of the drilling fluid used,such as sticking and well leakage. In this paper,the screening and evaluation research of drilling fluid suitable for this block was studied,through performance tests,filtrate reducer,plugging agent and wetting agent were determined,and the optimal recipe of the drilling fluid system was determined as follows:3%caly+2% fluid loss agent SPNH +1% fluid loss agent SMP-1 +0.3% polyacrylicacid potassium+0.3% fluid loss agent PAC-LV +0.1% richmond agent XCD +2% low fluorescence collapse prevention agent SFT +2% blocking agent NFA-25 +2% film-forming blocking agent CMJ-2 + 2% comprehensive blocking agent ZHFD-1 + 0.3% polyamine inhibitor AP-2 + 5% white oil + 0.2%surfactant ABSN emulsifier+ barite. The density of the drilling fluid was 1.10-1.21g/cm3,the apparent viscosity was 33 mPa·s,the plastic viscosity was 24 mPa·s,the yield value(YP)was 9 Pa,the dynamic plastic ratio was 0.375,the filter loss in high temperature and high pressure was 10.0-11.0 mL,API filter loss was 2.5-2.8 mL,pH value was 8-9,and the density was controlled among 1.10-1.21 g/cm3. Application of the drilling fluid system in Well Bao 16-1 showed that,the drilling fluid system had low filter loss,good rheology and strong plugging and preventing collapse capability. The complex prescription was zero,the circle of drilling shortened,and the expanding rate of caliper reduced remarkably. Well Bao 16-1 was constructed smoother than the others drilled in the same structure,indicating that strong restraining and plugging polyamine class agents could solve the problem of stability of the well wall in this block effectively.