钻井液性能对火山碎屑岩崩解性的影响——以青海阿克楚克塞矿区火山碎屑岩为例

Effect of Drilling Fluid Properties on Pyroclastic Rock Collapsing:A Case Study of Pyroclastic Rock in Akechukesai Mining Area of Qinghai

为解决火山碎屑岩在钻进中易剥落、易崩塌的问题,探讨钻井液性能对火山碎屑岩崩解性的影响,以青海阿克楚克塞矿区火山碎屑岩为例,分析了其岩石样品的矿物成分,进行了岩石样品烘干和浸水循环实验,采用多元线性回归分析法分析了原1#、2#钻井液的主要参数和耐崩解性指数之间的关系。结果表明,钻井液的动塑比、静切力、失水量和漏斗黏度4项性能指标与火山碎屑岩崩解性的相关性可达83.37%,其中动塑比对火山碎屑岩崩解性的影响尤为显著。通过调整水解聚丙烯酰胺和褐煤树脂质量分数提高了钻井液的动塑比和稳定性,从而获得优选钻井液配方:水+4%膨润土+3%Na2CO3+0.1%NaOH+0.15%MV-CMC(中黏钠羧甲基纤维素)+0.5%LV-CMC(低黏钠羧甲基纤维素)+2%SPNH(褐煤树脂)+0.08%PHP(水解聚丙烯酰胺)。现场应用表明,钻进至429.00m深度时使用优选钻井液孔底沉渣厚度较1#钻井液降低了89.7%,较2#钻井液降低了80.3%。

In order to solve the problem of exfoliation and collapse of pyroclastic rocks during drilling,the authors studied the effect of drilling fluid performance on the disintegration of pyroclastic rocks.The samples of pyroclastic rocks in the Akechukesai mining area of Qinghai were taken to analyze the mineral composition of rocks,and the sample drying and soaking cycle experiments were carried out.The relationship between the main parameters of the original 1#and 2#drilling fluids and the slake durability index was analyzed by multiple linear regression analysis.It shows that the correlation between the dynamic performance ratio,static shear force,water loss,funnel viscosity of the drilling fluid and the disintegration of pyroclastic rocks can reach 83.37%.The effect of dynamic plastic ratio on the collapsing of pyroclastic rocks is particularly significant.By adjusting the mass fraction of hydrolyzed polyacrylamide and lignite resin to improve the dynamic fluid ratio and stability of the drilling fluid,the drilling fluid formulation is optimized as:water+4%bentonite+3%sodium carbonate+0.1%sodium hydroxide+0.15%medium viscosity sodium carboxymethyl cellulose+0.5%low viscosity sodium carboxymethyl cellulose+2%lignite resin+0.08%hydrolyzed polyacrylamide.The field application results show that when drilling to the depth of 429.00 m,the thickness of residual cuttings at the bottom of the hole with the optimized drilling fluid is 89.7%lower than that with the 1#drilling fluid,and 80.3%lower than that with the 2#drilling fluid.