张集煤矿多分支井强封堵防塌钻井液体系研究及应用

Study and application of drilling fluid system for strong plugging and collapse prevention in multi-branch wells of Zhangji Coal Mine

摘要:

张集煤矿多分支井是一口为查明3号异常区地质（陷落柱、薄煤带和地堑等）与水文地质特征开展的1直5支支井钻探工程。T3孔主要目的层为3_上和3_下煤层， 煤层机械强度低，裂缝和割理发育，均质性差，存在较高剪切应力作用，煤层段井壁极不稳定，在钻井过程中极易发生井壁坍塌、井漏、卡钻甚至埋掉井眼等井下复杂情况。本文通过对施工中钻井液的主要技术难点进行分析，研制了多分支井强封堵防塌聚合物钻井液体系，主要配方：基浆+0.5%KPAM+1%铵盐+1%腐殖酸钾+1%降滤失剂+1%防塌剂+3%NS封堵剂。主要性能：粘度35~50 s，密度1.05~1.2 g/cm³，失水量4~6 mL。完成钻井工程量2506.23 m，岩心取心率92%，满足了施工的要求。

Abstract:

Zhangji coal mine multi-branch well is a drilling project of 1 straight 5 branch wells deployed to find out the geological （collapse column， thin coal belt and graben， etc.） and hydrogeological characteristics of No.3 abnormal area.The main target layers of T3 hole are 3_up and 3_down coal seams， which have low mechanical strength， developed fractures and cleats， poor homogeneity and high shear stress. The wellbore of coal seam section is extremely unstable， and it is easy to cause wellbore collapse， lost circulation， stuck or even buried wellbore during drilling. By analyzing the main technical difficulties of drilling fluid operation， the polymer drilling fluid system for strong plugging and anti-sloughing of multi-branch wells is developed. The main formula is： base slurry+0.5%KPAM+1%ammonium salt +1%potassium humate+1%filtrate loss agent+1% anti-sloughing agent+3%NS plugging agent， viscosity 35~50s， density 1.05~1.2g/cm³， water loss 4~6mL. One main hole and five branch holes were drilled， drilling quantity was 2506.23m， hole formation rate was 100%， core recovery rate was 92%， which ensured the requirements of construction.