元坝地区高密度超高密度钻井液技术

Ultra-high Density Drilling Fluid Technology Used in Yuanba

元坝地区地质构造复杂,地层压力状况复杂多变,气藏储层存在较强的非均质性,局部存在有裂缝性高压气层,海相地层的嘉陵江组还可能钻遇高压盐水层。钻井施工过程中使用的钻井液密度多在2.20 g/cm3以上,最高达2.42 g/cm3,钻井液的流变性控制及抗污染能力的强弱成为保证井下施工安全的关键因素。根据室内研究及现场应用情况,形成了1套元坝地区使用的高密度超高密度钻井液技术,能够控制密度在2.40 g/cm3左右的钻井液的流变性,控制了酸根及盐膏污染,具有一定的抗温、抗污染能力。

Formations in Yuanba area have complex geological structure and varied formation pressures.Gas reservoirs in this area are highly heterogeneous,some of them are highly pressurized and fractured.High pressure brine zones may also be encountered in the marine facies Jialingjiang Formation.Drilling fluids used in this area have densities of mostly above 2.2 g/cm^3,even as high as 2.42g/cm^3,Rheology and contamination tolerance of drilling fluids with such high densities are critical to the success of drilling.A high density ultra-high density drilling fluid technology is developed for use in this area.This technology allows the drilling fluid to have a density as high as 2,40 g/cm^3,and to tolerate the contamination of carbonate,salt and gypsum,and the negative effect on drilling fluid of medium high temperatures.