澳大利亚M区块低煤阶煤层气井产能主控因素及合理开发方式

Main controlling factors of productivity and reasonable development methods of low-rank coalbed methane in block M of Australia

为了研究低煤阶煤储层资源,结合低煤阶煤层气井的生产特征和气田地质模型资料,建立了低煤阶煤层气井数值模型,并进行了产能影响因素敏感性分析,明确了影响煤层气井产能的主控因素,基于储层物性划分,开展了低煤阶煤层气合理开发方式的优化研究。结果表明:合采井纵向穿过J和T共2套煤层组,纵向储层控制程度高、排水量大,有助于降压解吸,增加单井产量;影响低煤阶煤层气井产能的主控因素有累计净厚度、渗透率、含气量、井距和含气饱和度;埋深<250 m的储层最优井距为1 500 m,埋深为250~350 m的储层最优井距为1 200 m,埋深为350~400 m和埋深为400~450 m的储层最优井距为1 000 m,埋深450~600 m的储层最优井距为800 m,埋深>650 m的储层最优井距为700 m。该项研究为气田的有利区筛选和开发优化提供了理论基础和技术支撑。

Low-rank CBM reservoir has rich resources and huge development value.Combined with the production characteristics of low-rank coalbed methane wells and geological model of gas field,a numerical model of lowrank coalbed methane wells was established,the sensitivity analysis of the factors affecting the productivity was carried out,and the main controlling factors affecting the productivity of coalbed methane wells were defined.Based on the division of reservoir physical properties,the optimization study of reasonable development methods of low-rank coalbed methane was conducted.The results show that the commingled producing well passing through JJ and TT two sets of coal seam groups longitudinally had high degree of vertical reservoir control and large drainage,which is helpful for pressure reduction and desorption.Therefore,the commingled wells greatly increased the average single well production.The main controlling factors affecting the productivity of low-rank coalbed methane wells are cumulative net thickness,permeability,gas content,well spacing and gas saturation.Through the optimization analysis of well spacing for six types of reservoir,for the reservoirs with buried depth less than 250 m,the optimal well spacing is 1 500 m;for the reservoirs with buried depth of 250-350 m,the optimal well spacing is 1 200 m;for the reservoirs with buried depth of 350-450 m,the optimal well spacing is1 000 m;for the reservoirs with buried depth of 450-600 m,the optimal well spacing is 8 00 m;for the reservoirs with buried depth greater than 600 m,the optimal well spacing is 700 m.This study could provide theoretical basis and technical support for the selection and development optimization of favorable areas in gas fields.