秋南1井高密度钻井液应用技术

The Application of High Density Drilling Fluid in Well Qiunan-1

秋南1井是塔里木盆地库车凹陷东秋构造带上的一口重点超深预探井，完钻井深为7003m。该井自三开吉迪克组地层以下均采用KCl-欠饱和盐水高密度钻井液，钻井液密度最高达2．28g／cm^2；至完钻时，使用高密度钻井液施工了16个多月。应用结果表明，该钻井液具有良好的抗温性（150℃）；控制钻井液pH值为9～10，既有利于处理剂功效的发挥，又有利于保持钻井液有良好的热稳定性；在钻井液中加入表面活性剂和抗氧化剂，有利于抑制黏土水化分散、高温表面钝化，提高了钻井液的高温稳定性；高软化点沥青在高温条件下有良好的变形性，有利于改善泥饼质量，从而降低高温高压滤失量。但是，目前国内适合高密度钻井液的抗高温、抗污染处理剂种类少，选择面小；高密度钻井液的抗污染问题还没有得到很好的解决，现场只有采用置换的办法处理，造成维护处理成本增加，需要继续对抗高温、抗污染钻井液配方及应用工艺技术进行研究。

Well Qiunan-1,7,300 m in depth,is a key ultra deep exploration well drilled in Tarim Basin.When drilled to the Jidike Formation in the third interval of the well,high density(2.28 g/cm3) KCl-undersaturated mud was used in this well for 16 months by the end of the well.The filed practice showed that this mud had a good temperature stability(150 ℃).pH of the fluid,controlled between 9 to 10,will be beneficial not only to the best function of the mud,but also to the stability of the mud at elevated temperatures(coupled with the addition of oxygen scavenger).High softening point asphaltene helps improve the cake quality and the filtration performance of the mud.Contamination to the high density drilling fluid cannot be avoided for the time being because of the shortage in contaminant-tolerant additives supply,and the contaminated mud is generally discarded and new mud added,thus leading to a high mud cost.This problem is yet to be solved.