Organization
SINOPEC East China Oil & Gas Company, Nanjing, Jiangsu 210019, China
摘要
渝东南地区常压页岩气区块处于盆缘过渡带—盆外褶皱区，具有构造复杂、应力差异大、压力系数低等地质特点，给工程工艺提效增产带来巨大挑战。该区浅表层缝洞发育、漏失层位多，钻完井周期长；构造应力变化快、差异系数大，压裂难以形成复杂缝网；地层能量不足、排液效率低，影响气井连续稳定生产。为此以“四提”为目标，创新实践关键技术，工程工艺持续创效。钻井工程围绕“提速、提效、降本”攻关形成以井身结构优化、强化参数钻井为主，设备、工具一体化配套的常压页岩气钻完井技术，机械钻速年均提高14.90%，钻完井周期降幅10.67%，钻井成本降幅7.64%，刷新同期多项纪录。压裂工程围绕“增效降本”，通过“适度密切割+暂堵转向”提升裂缝复杂度，“高强度加砂+砂陶粒径组合”促进缝网多尺度有效支撑，集成应用低成本压裂材料与提速降本设备工具，形成“复杂缝网+经济型材料+智能压裂装备”的特色压裂工艺及配套，单井归一千米最终可采储量(EUR)由0.34亿立方米提升至0.45亿立方米，费用下降34.6%。排采工程以“全生命周期精细管理、延缓递减、挖潜增效”为目标，攻关建立了早期优选管柱、中期泡排+压缩机降压开采、后期单管射流泵、强力泵+尾管等机械排采的全生命周期排水采气技术体系，实现了分区分类分阶段精准施策，老井年递减率降低2.1%，全气田生产时率从95.9%提升至98.7%。通过工程工艺的全流程攻关，有力支撑了渝东南常压页岩气的效益开发，也可为其他常压页岩气的高效开采提供借鉴。
Abstract
The normal-pressure shale gas block in southeast Chongqing is located in the transitional zone of the basin margin and the extrabasinal fold area, which has the geological characteristics of complex structure, large stress difference and low pressure coefficient, which brings great challenges to improve the efficiency and production of engineering technology. Shallow surface fractures and caverns are developed in this area, with many thief zones, and long drilling and completion period. The structural stress changes quickly and the difference coefficient is large, so it is difficult to form complex fracture network. The lack of formation energy and low drainage efficiency affect the continuous and stable production of gas wells. Therefore, with the goal of “increasing quality, speed, efficiency and yield”, key technologies are innovated and implemented, and the benefits of engineering processes are created constantly. With the aim to “speed up, improve efficiency and reduce cost” in drilling projects, the normal-pressure shale gas drilling and completion technology is formed, which focuses on well structure optimization and drilling with optimized parameters, and integrates equipment and tools. The mechanical drilling rate increases by 14.90% per year, the drilling and completion period decreases by 10.67%, and the drilling cost decreases by 7.64%, setting multiple new records in the same period. Focusing on increasing efficiency and reducing cost of fracturing projects, fracture complexity is improved through “moderately close cutting + temporary plugging and turning”, effective multi-scale support of fracture network is promoted by “high-strength sand injection + sand-ceramic particle size combination”, low-cost fracturing materials and cost-reduced equipment and tools are integrated and applied, forming the characteristic fracturing process and supporting facilities of “complex fracture network + economic materials + intelligent fracturing equipment”. The final EUR of one kilometer per well was increased from 34 to 45 million cubic meters, and the cost decreased by 34.6%. With the goal of “fine management of the whole life cycle, delay of decline, and efficiency improvement by tapping the potential”, the full-life cycle drainage and gas production technology system of mechanical drainage such as early selection of pipe string, mid-stage foam drainage + compressor depressurized mining, late-stage single pipe jet pump and heavy-duty pump + liner pipe has been established, and precise policies have been implemented in different areas, classification and stages, and the annual decline rate of old wells has been reduced by 2.1%. The production time rate of the whole field increased from 95.9% to 98.7%. Through the research on the whole process of engineering technology, it strongly supports the efficient development of normal-pressure shale gas in southeast Chongqing, and provides beneficial reference for the efficient exploitation of other normal-pressure shale gas.
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