摘要
沁水盆地南部高阶煤层多分支水平井钻井施工中遇到了以下难题:①井壁稳定性差,容易发生井下复杂事故;②煤层易受污染,储层保护难度大;③岩屑携带不畅,井壁严重失稳;④缺乏先进适用的钻井工具及仪器。为解决上述问题,分析了多分支水平井井眼轨迹及分支结构优化设计、复合造穴、水平井与洞穴井连通、井眼轨迹控制、充气欠平衡钻井等关键技术的要点,结合现场先导试验实施情况和效果,综合研究后认为:①沁水盆地3#煤层分布稳定、煤层平坦、煤岩机械强度相对较高、煤层顶板稳定,适于采用多分支水平井钻井技术来开发煤层气,而且利用国内现有技术和装备完全可以实施多分支水平井钻井施工;②在该区实施充气欠平衡钻井应尽量选取小的欠压值,或者保持近平衡钻进,重点应放在辅助清水钻井液携岩方面;③高阶煤层比较脆且存在互相垂直的天然裂缝,极易引起井下垮塌、卡钻等复杂事故,甚至造成井眼报废,钻进过程中要密切关注钻井参数的变化,及时调整钻井参数,防止井下发生复杂事故;④储层保护、携带煤屑和井壁稳定仍是高阶煤层多分支水平井亟待攻克的技术瓶颈。
Great difficulties have been encountered in the drilling of multi-branch horizontal wells in the Qinshui Basin with high-rank coal beds.(1)Poor wellbore stability will result in kinds of downhole accidents;(2)Reservoir protection becomes difficult due to the easily contaminated coal seams;(3)Unsmooth cuttings carrying leads to severe wellbore instability;(4)There is lack of advanced and appropriate drilling tools and instruments.In view of this,this paper first focuses on the involved key techniques including the optimal design of multi-branch well type and well trajectory,composite local diameter enlargement,inter-connection between horizontal wells and caved holes,trajectory control,and the air and underbalanced drilling,etc.Then,in combination with the field cases for the pilot tests and their results,an overall study draws the following conclusions:(1)The No.3coal bed in the Qinshui Basin is in stable and flat distribution,where the mechanical strength of coal rocks is relatively high with a steady cap rock integrity.All these provide good conditions and the possibilities for the multi-branch horizontal drilling there by use of the existing domestic technology and equipment.(2)The air and underbalanced drilling there should adopt a minimum underbalance value or remain the near balance condition.Much concern should be paid to the purpose of cuttings carrying through the clean water as the drilling fluids.3)High-rank coals are brittle and natural fractures are perpendicular to each other,which results in downhole collapse and sticking,even the wellbore abandonment.Any changes of drilling parameters should be closely concerned and timely adjusted to prevent any possible downhole accidents.(4)Reservoir protection,cuttings carrying,and wellbore stability are still the bottlenecks of multi-branch horizontal well drilling in the high-rank coal beds.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2011年第11期18-21,119,共4页
Natural Gas Industry
关键词
沁水盆地南部
高阶煤层
煤层气
多分支水平井
钻井工艺技术
可行性
欠平衡钻井
钻井参数
Qinshui Basin,south,Shanxi,high-rank coal bed,multi-branch horizontal well,drilling technology,feasibility,under-balanced drilling,drilling parameters
作者简介
作者简介：崔树清，1967年生，高级工程师，博士；毕业于中国地质大学（北京），现从事钻井技术管理及研究工作。地址：（062552）河北省任丘市中国石油华北油田公司钻采工程部。电话：（0317）2780242。E—mail：bh_cui@petrochina．com．cn.
