委内瑞拉奥里诺克胡宁区块丛式三维水平井安全钻井技术

委内瑞拉奥里诺克胡宁区块储层埋藏浅,地层疏松,丛式三维大位移水平井具有位移大(1 300 m以上),水垂比高(3.1~4.5),井眼曲率大(7°/30 m~10°/30 m)的特点,钻井作业面临井眼轨迹控制难、摩阻扭矩大、井壁稳定性差以及尾管下入困难等技术难点。为此,通过对平台内不同偏移距下的三维井摩阻扭矩分析、井眼轨迹优化设计、极限井深模拟计算以及钻井液体系与配方优选,有效解决了因垂深浅、水平段长引起的钻具摩阻扭矩大与托压问题,以及弱固结性疏松砂岩储层井壁失稳和储层保护等技术难题;采用漂浮下套管并配合井口加压的复合技术来解决套管下入设计深度问题。该研究成果在胡宁区块现场应用7口水平井,其中E3-23井完钻垂深仅375.3 m,而斜深为1 984.1 m,水平位移达1 688.4 m,水垂比达到4.5,成为目前已钻完井中水垂比最大的三维水平井。该项技术可为国内浅层油气田高效开发提供借鉴。

Drilling safety technologies for 3D cluster horizontal wells of Junin Block in Orinoco,Venezuela

The reservoirs of Junin Block in Orinoco, Venezuela, are shallow and unconsolidated. 3D extended-reach cluster horizontal wells are characterized with large displacement (over 1300 m), high horizontal displacement to vertical depth ratio (3.0–4.5) and high borehole curvature (7°/30m–10°/30m). Therefore, drilling operations in this block are technically challenged with difficult well trajectory control, large drag and torque, poor wellbore stability and difficult liner lowering. Solutions were figured out to the problems of high drag and torque and backing pressure of drilling tools caused by shallow vertical depth and long horizontal intervals and the wellbore stability and reservoir protection of weak-consolidation unconsolidated sandstone reservoirs were guaranteed by taking a series of measures , including 3D well drag and torque analysis at different offsets, well trajectory optimization design, ultimate well depth simulation and calculation, and drilling fluid system and formula optimization. The correlation between the well which was being drilled and its neighboring wells was calculated and scanned in time. When their space was close to 5 m, some measures were taken. Drilling platforms and vibrating sieving meshes were also real-time monitored, so as to stop the drilling in case of abnormal conditions. The combined technology of floating casing running and wellhead pressurization was used to run the casing down to the design depth. The research results were applied in 7 horizontal wells in the Junin Block. Among all the drilled wells, Well E3-23 is the 3D horizontal well with maximum horizontal displacement to vertical depth ratio (4.5), and its total vertical depth is only 375.3 m, along-hole depth 1984.1 m and horizontal displacement 1688.4 m. This technology provides a reference for the efficient development of domestic shallow oil and gas fields.