东方A气田浅层大位移钻井关键技术研究

Research on Key Technologies of Shallow Extended Reach Drilling inDongfangAGas Field

针对东方A气田大位移井开发过程中面临浅部松软地层轨迹控制难度大、长裸眼段钻进摩阻扭矩高、套管下入困难、后期开发储层出现压力衰竭引起井漏等技术难题,从井身结构、定向井设计、钻具组合、钻井液性能、漂浮旋转下套管等方面进行技术研究。结果表明:设计?508.0 mm隔水套管入泥深度87 m能够满足松软地层承压能力和井口载荷要求;轨迹造斜率设计3°/30 m和(1.5+2+2.5)°/30 m相结合方案降低防碰风险和钻进摩阻扭矩;浅部地层使用1.5°高弯角马达和指向式旋转导向两趟钻降低轨迹控制难度;根据不同摩阻系数分析套管下入的极限情况,计算合理漂浮套管长度;在油基钻井液中加入超细碳酸钙提高衰竭地层承压能力。P2H井结合相关技术措施钻进至5 960 m完钻,该井水平位移5 325 m,水垂比3.87,创造了南海西部浅层大位移井纪录。

Dongfang A gas field faced many technical problems during the development of extended reach well,such as difficulty in shallow sof formation trajectory control,high friction and torque in long open hole section drilling,difficulty in casing running,pressure failure of late developed reservoir and easy to cause leakage,etc.Technical research was carried out from the aspects of well structure,directional well design,drlling assembly,drilling fluid properties,floating and rotating casing.The results show that the design of 508.0 mm non-standard size waterproof casing with a mud depth of 87 m can meet the pressure bearing capacity of soft formation and wellhead load requirements.The combination of trajectory building slope design of 3/30 m and(1.5+2+2.5)/30 m reduces the risk of collision and drilling drag and torque.In shallow formations,1.5°high angle motor and directional test rotary steering are used to reduce the difficulty of trajectory control.According to the different friction coefficient,the limit conditions of running are analyzed,and the reasonable floating casing length is calculated.Ultrafine calcium carbonate is added to oil-based drlling fluid to improve pressure bearing capacity of depleted formation.Combined with relevant technical measures,well P2H is drilled to 5960 m,the horizontal displacement of the well is 5325 m,and the water-sag ratio is 3.87,which breaks through the existing limit of the water-sag ratio of shallow extended reach wells in the west of the South China Sea.