深部煤层气水平井测-定-录一体化地质导向技术

Integrated geo-steering technology of logging and orientation in deep coalbed methane horizontal well

  • 摘要: 我国深部煤层气资源丰富,目前已逐步进入勘探开发阶段,但经济高效的煤层气井数量偏少。钻井工程导向技术是制约煤层气水平井产能的首要因素:一方面,要求着陆井段轨迹平滑,使着陆层位和角度与地层参数相互匹配,以免造成后期排采设备故障率高、排采不连续的现象;另一方面,水平段煤层钻遇率尽可能高,以保障供气充足。基于此,在总结前期深部煤层气水平井地质导向经验基础上,提出集测井、定向、录井技术于一体的地质导向技术,最大限度优化井眼轨迹,提高靶点着陆准确度和水平段煤层钻遇率。该技术主要流程为:根据前期有限的钻探、地震等资料建立目的层地质模型,钻井工程实施过程中通过垂直井段获取钻遇地层的测井参数响应值,水平段钻进时实时对比定向和录井参数,及时校正随钻伽玛,利用GeoWorks软件进行层位对比和划分,并建立动态地质模型,进而调整和预测后续井眼轨迹。通过沁水盆地横岭区块HL-U-04井实例应用,该技术取得了良好的应用效果,施工周期缩短了30%,煤层钻遇率提高了24.47%。该井完钻后连续油管压裂套管压力在5.7 m3/min的排量下稳定维持在35 MPa,达到了储层改造效果,投产后该井排采初期日产气量稳定在1000 m3左右。因此,测-定-录一体化地质导向技术提高了水平井钻井技术的精确性和高效性。

     

    Abstract: China is rich in deep coalbed methane (CBM) resource,which has gradually entered the stage of exploration and development. However,the number of cost-effective CBM wells is relatively small. Drilling technology is the dominate factor restricting the productivity of CBM horizontal well. On the one hand,the track of landing well section is required to be smooth,contributing to the match between landing horizon,angle and formation parameters,which avoids high failure rate of drainage equipment and discontinuous drainage. On the other hand,the drilling intercept rate of coal seam in horizontal section must be as high as possible to ensure sufficient gas supply. Therefore,on the basis of the geo-steering experience of deep CBM horizontal wells in the early stage,this study puts forward the geo-steering technology which integrates well log,orientation and mud logging technology to optimize the well trajectory and improve the landing accuracy of target and the coal seam drilling intercept rate in the horizontal section. The main process of this technology is as follows:first establishing the geological model of the target layer according to the limited drilling and seismic data in the early stage,then obtaining the response value of the logging parameters of the drilled formation through the vertical well section during the implementation of the drilling project,comparing the directional and logging parameters in real time when drilling in the horizontal section,and correcting the gamma while drilling in time,then using the GeoWorks software to carry out the layer comparison and division,finally establishing the dynamic geological model to adjust and predict the follow-up well trajectory. Through the application of well HL-U-04 in Hengling block of Qinshui Basin,the technology has achieved a good application result. The construction period was shortened by 30% ,and the coal seam drilling intercept rate was increased by 24. 47% . After the completion of drilling,the fracturing casing pressure of coiled tubing was stable at 35 MPa with the displacement of 5. 7 m3/ min,which achieved the effect of reservoir reconstruction. During production,the daily production of the well was stable at about 1 000 m3 at the initial stage of production. Therefore,the integrated geo-steering technology of logging and orientation improves the accuracy and efficiency of horizontal well drilling technology.

     

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