威远区块页岩气水平井产量主控因素分析

An Analysis of Main Controlling Factors of Production for Horizontal Shale Gas Well in Weiyuan Block

四川盆地威远区块国家级页岩气示范区开发效果显著,但仍存在单井产量差异较大的问题,深入分析页岩气水平井高产的主控因素是目前研究的重点。利用威远示范区取芯井地质及测井资料明确龙马溪组龙一11小层作为最优开发层系,开展储层精细评价研究,结合水平井压后评价建立了储层厚度、最优靶体位置、Ⅰ类储层钻遇率与产量之间的关系,明确了天然裂缝发育程度对水平井产量的影响,定量计算了压裂液量、砂量和排量3项工程参数与缝网有效性的关系。结果表明:(1)龙一11小层厚度与产量呈高度正相关;(2)距离龙一11小层底部距离0~4m是最优靶体位置;(3)Ⅰ类储层钻遇率的高低直接影响着水平井高产与否;(4)天然裂缝发育有利于页岩气获得较高产量;(5)根据工程参数定义的缝网综合有效系数达到0.8以上时,可认为形成了有效的页岩气流动通道。

Pilot development in the Weiyuan national shale gas demonstration area in the Sichuan Basin but the test production rates of different wells show a great variety.In view of this,the research focuses on the main factors controlling the high production of horizontal shale gas wells in this area.Using the geological and logging date of coring wells confirm that Long Ⅰ11 sublayer of Longmaxi Formation is the best development strata.Combining detailed reservoir studies fracturing evaluation of horizontal wells,we establish the relationship between reservoir thickness,optimal target position,the drilling rate of Type I reservoirs and the production of gas wells,and confirm the natural fracture development and its impact on horizontal well productivity.The relationship between the effectiveness of the fracture network and fluid volume,sand volume and pipe rate was calculated.The results indicate:(1) there is a highly positive correlation between the thickness of the Long Ⅰ11 sublayer and production;(2) distance from the bottom of Long Ⅰ11 sublayer 0~4 m is the optimal target position;(3) the drilling rate of Type I reservoirs has a direct effect on the high production of gas wells;(4) the natural fracture development are highly relate to single well production;(5) the defines the comprehensive coefficient of fracture network is above 0.8,which can provide effective channel for shale gas flow after fracturing.