准噶尔盆地南缘H101井高密度油基钻井液技术

准噶尔盆地南缘H101井三开井段安集海河组地层以泥岩为主,在钻井过程中因泥岩水化膨胀、分散造浆而造成高密度钻井液维护处理困难、井壁垮塌、卡钻等井下故障,为此设计应用了高密度油基钻井液。根据安集海河组地层的特点、油基钻井液的实践及钻井要求,确定了高密度油基钻井液配方,并对其流变性、稳定性及抗污染性能进行了评价,结果表明,流变性、稳定性及抗污染性能达到设计要求。H101井三开井段钻进安集海河组地层过程中,高密度油基钻井液的密度最高达2.46 kg/L,除出现几次阻卡现象外,未发生其他井下故障。与邻井相比,三开井段平均机械钻速提高6倍以上,钻井周期缩短100 d以上。这表明,使用高密度油基钻井液可以解决安集海河组地层钻井过程中存在的卡钻、井漏等井下故障,并能提高机械钻速,降低钻井成本。 

High Density Oil-Based Drilling Fluid Deployed in Well H 101 in the Southern Margin of the Junggar Basin

The Anjihaihe Formation formation in the third spud-section of Well H101 in the Southern Margin of Junggar Basin is dominated by mudstone.During drilling, shale hydration expansion and the dispersal mud may sometimes make it difficult to maintain desirable performances with high specific-gravity oil-based drilling fluid.At the same time, borehole wall collapse, sticking and other downhole problems may be encountered.To eliminate these problems, high specific-gravity oil-based drilling fluids have been designed and deployed.With consideration to specific characteristics of the Anjihaihe Formation, the performance of the oil-based drilling fluid and the requirements of drilling operations, a formula for high specific-gravity oil-based drilling fluid has been determined.In addition, its rheology, stability and pollution resistance performances were assessed.Relevant results showed that, the rheology, stability and pollution resistance capacities of the drilling fluid can meet the design requirement.The density of the high specific-gravity oil-based fluid is up to 2.46kg/L during drilling of the in the Anjihaihe Formation in the third section interval of the Well H101.No downhole problems have been encountered except a few sticking situations.Average ROP in the third section is 6 times higher than those of adjacent wells in the area, whereas the drilling cycle shortened more than 100 d.Relevant results showed that the high density oil-based drilling fluid system could effectively remove stuck drilling pipe, avoid lost circulation downhole fault in Anjihaihe Formation drilling process.In addition, the system could improve the rate of penetration and reduce drilling costs.