美国Barnett页岩气开发中应用的钻井工程技术分析与启示

Technology Analysis and Enlightenment of Drilling Engineering Applied in the Development of Barnett Shale Gas in America

美国Barnett页岩气开发十分成功,有较多经验可供参考。井身结构设计要满足多次压裂的增产方式和长达30～50a生产周期的要求;丛式井成为降低开发成本、增大对储层控制能力的有效技术;水平井技术是页岩气开发的关键技术,水平井的成本一般是垂直井的1～1.5倍,而产量是垂直井的3倍左右;水平段钻进中,常使用油基钻井液和PDC钻头,在保持水平井眼稳定性的同时,提高机械钻速;低密度、高强度固井完井技术,能为后期储层改造和开发做好准备;随钻伽马测井曲线,可用于较准确地识别页岩储层,若水平井技术结合geo VISION随钻成像服务和RAB钻头附近地层电阻率仪器等LWD技术,可以更为合理的控制井眼轨迹。提出国内钻井工程技术集成与发展的建议:实现地面上集成、集中的"小间距丛式井组"(井工厂),做到"组少井多";实现储层中水平井眼轨道空间分布,合理开发"地下立体井网",做到"少井高产和高采收率";追求"钻井速度高、井眼质量好、钻井成本低"的钻井模式;开展长水平段水平井或水平分支井钻井技术的整体研究:研究满足后期开发和压裂需求的完井方式,在成本允许的条件下采用泡沫水泥固井技术,研制特殊套管、封隔器、分支工具等材料和新型井下工具。

Barnett shale gas is developed successfully in America providing many experiences.The design of hole structure must need the demands of stimulation by multiple fracturing and long production cycle of 30-50 years.Cluster well has become the effective one for decreasing cost of development and strengthening the control to reservoirs.Horizontal well is the key technique for the development of shale gas,whose cost is 1-1.5 times of the vertical well and whose production is about 3 times of the vertical well.During the drilling of the horizontal section,oil-based drilling fluid and PDC bit are usually used for holding the horizontal hole stability and enhancing rate of penetration.Well cementation and completion at low density and high strength may get ready for later reservoir reconstruction and production.Gamma ray log while drilling can be used for recognition of the shale reservoir correctly.The combination of the horizontal well and LWD technique（such as geo VISION imaging during drilling and the equipment of formation resistivity near RAB drill bit） may control the well track rationally.A suggestion of technique integration and development of China drilling engineering is proposed： on the surface,integrated and centralized ＂small-interspacing cluster well group＂（well plant） makes the structure of less groups and more wells;in the reservoir,reasonable spatial distribution of horizontal hole track with ＂underground stereo well pattern＂ make high output and recovery efficiency by few wells;drilling pattern should be ＂high drilling speed,good quality of borehole,and low drilling cost＂.Comprehensive research of drilling technology should be made on the horizontal well with long horizontal interval or horizontal multilateral well.Well completion system meets the demands of later development and fracturing should be researched.Cementing technology of foamed cement may be applied under the condition of the cost permitted.Special casing,packer,multilateral tool and new-type of down hole tool should be developed.