川东北元坝地区陆相地层井壁稳定技术研究

发布时间：2018-12-29 12:58

【摘要】：川东北元坝地区陆相失稳地层主要集中在陆相的沙溪庙组-须家河组顶部,失稳原因主要为：空气钻井震动产生、气液转换过程中滤液的侵入导致泥页岩产生膨胀及分散进而引起井壁垮塌、液体欠平衡钻井导致井壁力学不稳定三种,失稳现象主要为井壁掉块、垮塌。陆相地层泥页岩占比例较高,达70%以上,蓬莱镇组-上沙溪庙组泥岩质纯、性脆、较硬,而下沙溪庙组-须五段泥岩性软、吸水性、可塑性强；同时,上沙溪庙组-自流井组含有页岩,页理较发育,可剥成极薄的页片状。通过粘土矿物分析、电镜扫描以及线性膨胀、分散实验等方法,元坝地区泥页岩属于硬脆性泥页岩,伊利石含量普遍高于50%,膨胀性低,分散性弱,微裂缝发育,应力敏感性较强。针对川东北元坝地区陆相地层井壁失稳现象,根据地层压力变化,积极调整钻井液密度,欠平衡钻进过程中,欠压值不宜过大,在目前基础上应提高钻井液密度0.1-0.2g/cm3。同时,钻井液防塌应以“提高封堵防塌能力为主,兼顾抑制性”。通过对封堵剂的优选,优选出阳离子乳化沥青等关键处理剂,进一步提高钻井液封堵性能。针对气液转换过程中的井壁失稳现象,通过表面张力等实验方法,优选出润湿反转剂,优化形成全油基前置液配方及工艺。通过在YB10-1H井、YL601H井开展了油基前置液的现场应用,试验井划眼时间平均为31h,较非试验井划眼时间73.5h大幅降低。以“封堵+密度控制”为主的防塌钻井液技术在YB10-1H井、YL601H井成功进行了应用,井壁稳定效果显著,YB10-1H井三开井段平均井径扩大率仅为5.5%,远低于设计要求的12%。通过现场的成功应用,最终形成了一套适合川东北元坝地区陆相地层井壁稳定技术,满足了钻井施工需要。
[Abstract]:The terrestrial instability strata in Yuanba area of northeast Sichuan are mainly concentrated on the top of Shaximiao formation and Xujiahe formation in the continental facies. The main causes of instability are the vibration of air drilling. In the process of gas-liquid transformation, the invasion of filtrate leads to the expansion and dispersion of shale, and then to collapse of wellbore. There are three kinds of instability in wellbore mechanics caused by liquid underbalanced drilling. The main phenomena of instability are wellbore block loss and collapse. The mudstone of Penglai Zhen formation and Upper Shaximiao formation is pure, brittle and hard, while the lower Shaximiao formation is soft, absorbent and plastic. At the same time, the Upper Shaximiao formation-Ziliujing formation contains shale, the foliation is relatively developed and can be stripped into extremely thin sheet. By means of clay mineral analysis, scanning electron microscope, linear expansion and dispersion test, the shale in Yuanba area belongs to hard and brittle shale, the content of Illite is generally higher than 50%, the swelling property is low, the dispersity is weak, and the microfracture is developed. Stress sensitivity is strong. In view of the instability phenomenon of wellbore in the Yuanba area of northeast Sichuan, according to the change of formation pressure, the density of drilling fluid should be adjusted actively, and the under-pressure value should not be too large in the process of underbalanced drilling. The density of drilling fluid should be increased by 0.1-0.2g / cm ~ 3. At the same time, the sloughing prevention of drilling fluid should be based on improving plugging and sloughing prevention ability. Through the optimization of plugging agent, cationic emulsified asphalt and other key treatment agents were selected to further improve the plugging performance of drilling fluid. In view of the instability of wellbore in the process of gas-liquid conversion, the wetting reversal agent was selected by surface tension experiment, and the formulation and process of the whole oil based preliquid was optimized. Through the field application of oil-based precursor in YB10-1H well, YL601H well, the average drilling time of test well is 31 h, which is much lower than that of non-test well in 73.5 h. The anti-sloughing drilling fluid technology based on "plugging density control" has been successfully applied in YB10-1H well and YL601H well has been successfully applied. The effect of sidewall stabilization is remarkable. The average diameter expansion rate of the third section of YB10-1H well is only 5.5. It is far below the design requirement of 12. Through the successful application in the field, a set of well-wall stabilization technology suitable for the continental formation in Yuanba area of northeast Sichuan has been formed, which meets the requirements of drilling construction.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE28

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