新疆乌鲁木齐头屯河矿区煤层气井钻探施工技术探讨
发布时间:2018-06-25 来源: 散文精选 点击:
摘要:新疆乌鲁木齐头屯河地区地层较为破碎、地层裂隙发育比较严重,而且煤层气井煤储层埋藏浅、煤層压力低和煤层保护难度大,这些对煤层气井的钻探提出了更高的技术要求。针对目前头屯河地区钻探施工存在的问题和难点,通过井壁稳定的力学分析方法提出井身结构应选择直井。依据空气欠平衡钻井技术与常规钻井技术对煤层的污染和破坏程度,提出采用空气欠平衡钻井技术,采用低固相或无固相钻井液。根据水泥浆顶替流态的计算方式,计算出水泥浆顶替应当采用塞流顶替。依据煤储层的保护要求提出一种新的煤储层保护方案,即使用绕煤层固井工具。
关键词:煤层气井;钻探;直井;塞流顶替;绕煤层固井
Discussion on drilling technology of coal-bed methane well in Toutunhe mining area of Urumqi City, Xinjiang Province
ZHAO Tao, CAI Shunshan
The 216 group, China National Nuclear CorporationUrumqi City, Xinjiang Province830011
Abstract: The stratum is cracked and the formation cracks are serious in Toutunhe area of Urumqi City, Xinjiang Province. But the coal-bed methane wells are buried in shallow stratum. Because of low coal seam pressure and the big difficulty in coal seam protection, it requires higher technology on the drilling of coal-bed methane wells. Aiming at these problems and difficulties in drilling construction in Toutunhe area, it is proposed that the wellbore structure should be the vertical well through the mechanics analysis of borehole stability. Based on the pollution and damage degree caused by the air under-balanced drilling technique and the conventional drilling technique, the air under- balanced drilling technique is proposed and low solid or solid free drilling fluid should be used. According to the calculation method of cement slurry displacement fluid flow, the cement slurry displacement should be the plug flow displacement. According to the protection requirement of coal reservoir, there is a new coal reservoir protection scheme, which is accomplished by around the coal seam cementing tool.
Keywords: coal-bed methane well; drilling; vertical well; plug flow displacement; bypass coal-bed cementing

引言
煤层气俗称“瓦斯”,是一种非常规天然气,以吸附或储集的方式存在于煤层孔隙中[1]。我国煤气资源储量丰富,约36.8万亿立方米,居世界第三位。新疆煤层气资源丰富,其中头屯河地区钻孔控制的0.3m以上的煤层22层,单层厚度在0.030m~22.22m,平均纯煤总厚53.31m。然而,由于头屯河地区地层较为破碎、地层裂隙发育比较严重,而且煤层气井煤储层埋藏浅、煤层压力低和煤层保护难度大的特点对于煤层气井的钻探提出了更高的技术要求,对于煤层气的勘探和开发提出了较大的考验。由于我国煤层气的利用和开发起步较晚,且我国煤层气储层特性较国外煤层气有较大区别[2-4],因此在煤层气井固井过程中存在着很多的问题和难点[5],对于新疆头屯河地区的煤层气开发来说也面临着诸多问题。
目前,头屯河地区煤层气资源正处于调查评价阶段,由于煤层具有特殊物性,煤层气的开采一般都采用大型水力压裂,因此煤层气井的钻探施工工艺将大大影响后期煤层气的产量。所以,本文将针对目前头屯河地区钻探施工存在的问题和难点,提出井身结构应选择直井,采用空气欠平衡钻进技术,采用低固相或无固相钻井液,水泥浆顶替应当
采用塞流顶替并提出一种新的煤储层保护方案。本文希望通过对新疆头屯河地区煤层气井钻探施工方案的探讨,讨论并优化煤层气井钻探方案,希望能够提高头屯河地区煤层气井施工质量,为解决头屯河地区煤层气井钻探施工时存在的技术难题提供有效途径。
1.区域地质概况
勘查区位于东南沟向斜的北翼,总体为一向西南倾斜的单斜构造,倾角多在10°~85°,沿走向和倾向变化较大,沿走向自西向东由10°变化到85°左右,沿倾向由浅至深由20°变化到50°左右。勘查区构造复杂程度属中等类型,即“二类”。勘查区内出露的地层由老至新有中石炭统奇尔古斯套群(C2qr)、侏罗系下统三工河组、侏罗系中统西山窑组(J2x)、侏罗系中统头屯河组(J2t)、和第四系(Q4)。
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