适用于页岩油钻井的低伤害防塌水基钻井液体系  

Low Damage Highly Inhibitive Water Based Drilling Fluid for Drilling Shale Oil Reservoir

作　　者：艾磊 高云文 欧阳勇 辛庆庆 周宇 AI Lei;GAO Yunwen;OUYANG Yong;XIN Qingqing;ZHOU Yu(Oil and Gas Technology Research Instiute,Changqing Oilfield Company,China National Petroleum Corporation,Xi'an,Shaanxi 710018)

机构地区：[1]中国石油天然气股份有限公司长庆油田分公司油气工艺研究院,西安710018

出　　处：《钻井液与完井液》2023年第5期602-610,共9页Drilling Fluid & Completion Fluid

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“中低熟页岩油原位转化基础理论研究与关键技术开发及先导试验”(2021DJ5203)。

摘　　要：长73页岩储层发育微纳米级孔缝,地层岩石强度低,钻井液滤液易侵入储层造成井壁失稳和储层伤害。厘清了长73页岩井壁失稳机理及钻井液技术难点,借鉴“1/3和2/3架桥封堵规则”,引入刚性和可变形封堵材料,构建了广谱型多级粒径分布区间。以瞬时滤失量为评价指标,通过曲面响应建模优化出最佳配比,室内优选了防塌抑制剂组合,在此基础上研发出一套低伤害强防塌水基钻井液体系,评价实验结果表明,所构建的钻井液能够有效平衡地层坍塌应力,老化后静置72 h流变性依旧良好,抑制性强,页岩线性膨胀率较清水环境和现场钻井液分别降低了16.74%和13.61%;封堵性显著,瞬时滤失量仅为1 mL,对岩心的封堵率高达93.5%,储层保护性好,泥饼清除后岩心板中无孔喉堵塞现象,渗透率恢复值高达95.2%;润滑性能适中,钻井液老化前后摩阻系数均保持在0.08左右,现场试验水平段平均井径扩大率仅为4.27%,平均机械钻速可达18.4 m/h,钻进期间水平段无井下复杂事故,各项性能能够满足长73页岩油水平井钻井的需要。Chang 73 reservoirs have the characteristics of micron-nano crack development and low strength of formation rocks.It can lead to the intrusion of drilling fluid filtrate into the reservoir causing borehole collapse and reservoir damage.We clarified the destabilization mechanism of Chang 73 shale and the technical difficulties of drilling fluids.Then the multi-stage particle size distribution intervals with broad spectrum was constructed by introducing rigid and deformable plugging materials,which was based on the"1/3 and 2/3 bridging rule".Next,using the instantaneous water loss as the evaluation index,the optimal ratio was optimized by surface response modeling,and the combination of anti-collapse inhibitor was preferred in the room.Based on which a low damage and anti-collapse water-based drilling fluid was developed.The results of the evaluation indicated that the drilling fluid can effectively balance the formation collapse stress,and the rheological properties remain satisfactory after aging for 72 h.It also reduced shale linear swell by 16.74%and 13.61%compared to clear water environments and in the field drilling fluids respectively.Due to its remarkable plugging properties,the instantaneous filtration loss of the drilling fluid was only 1mL and the plugging rate of the core was as high as 93.5%.Based on the reservoir protection capability of the drilling fluid,there was no pore throat plugging in the core slab after mud cake removal and the permeability recovery value of the core was as high as 95.2%.It was important that the lubricity of the drilling fluid was moderate and the friction coefficient remain around 0.08 before and after the drilling fluid ages.The average diameter expansion rate of the horizontal section in the field test was only 4.27%,and the average mechanical drilling speed could reach 18.4m/h.There were no complicated downhole accidents in the horizontal section during the drilling period,and all the performances could meet the needs of horizontal wells in the Chang 73 reservoirs.

关 键 词：页岩油 水基防塌钻井液 封堵性 储层保护 

分 类 号：TE254[石油与天然气工程—油气井工程]