苏里格气田区小井眼二开水平井优化设计

Optimal Design of Slim-hole Second Spud Horizontal Well in Sulige Gas Field

小井眼二开水平井具有周期短、节省钻井成本的优点,但在钻进过程中会出现的井眼轨迹控制难、机械钻速(rate of penetration,ROP)慢、井壁易垮塌和易发生井漏等问题,针对上述问题对苏里格气田区小井眼水平井进行优化设计。井身结构的设计采用自下而上的设计原则,确定井身结构为小井眼二开水平井,二开结构可以减少下钻次数,缩短钻井周期;井眼轨迹设计采用五段制中的“直-增-稳-增-水平”井眼轨道设计,增加稳斜段弥补造斜不足的问题;针对钻遇地层特征优选钻具组合,应用聚晶金刚石复合片(polycrystalline diamond compact,PDC)钻头提高破岩效率;针对易塌易漏地层进行钻井液的分析研究,优选聚合物钻井液提高井壁稳定性。经过现场的应用,解决了井壁易塌易漏问题,提高了机械钻速,缩短了钻井周期。结果表明:小井眼二开水平井的结构设计合理,可以在现场进行推广。

Slim-hole second spud horizontal well has the advantages of short cycle and low drilling cost,but problems such as difficulty in wellbore trajectory control,slow rate of penetration(ROP),easy wellbore collapse and lost circulation may occur during the drilling process.Aiming at the above problems,the slim hole horizontal well in Sulige gas field was optimized.The design of the wellbore structure adopted the bottom-up design principle,and the wellbore structure was determined as a second spud horizontal well with a small hole.The second spud structure can reduce the number of drilling down and shorten the drilling cycle.In the design of borehole track,the five-stage system of"straight-accret-steady-accret-horizontal"borehole track was adopted,and the steady section was added to make up for the lack of deviation.Optimizing the drilling tool assembly according to the characteristics of the stratum encountered,and using the polycrystalline diamond compact(PDC)bit to improve the rock breaking efficiency.In the analysis and research of drilling fluid,polymer drilling fluid was preferred to improve wellbore stability.After on-site application,the problem of easy collapse and leakage of the well wall was solved,the ROP was improved,and the drilling cycle was shortened.The results show that the structural design of the second spud horizontal well is reasonable and can be promoted in the field.