A method is proposed to predict the flowing bottomhole pressures （FBHPs） for two-phase coalbed methane （CBM） wells. The mathematical models for both gas column pressure and two-phase fluid column pressure were dev...A method is proposed to predict the flowing bottomhole pressures （FBHPs） for two-phase coalbed methane （CBM） wells. The mathematical models for both gas column pressure and two-phase fluid column pressure were developed based on the well liquid flow equation. FBHPs during the production were predicted by considering the effect of entrained liquid on gravitational gradients. Comparison of calculated BHPs by Cullender-Smith and proposed method was also studied. The results show that the proposed algorithm gives the desired accuracy of calculating BHPs in the low- productivity and low-pressure CBM wells. FBHP is resulted from the combined action of wellhead pressure, gas column pressure and fluid column pressure. Variation of kinetic energy term, compressibility and friction factors with depth increments and liquid holdup with velocity should be considered to simulate the real BHPs adequately. BHP is a function of depth of each column segment. The small errors of less than 1.5% between the calculated and measured values are obtained with each segment within 25 m. Adjusting BHPs can effectively increase production pressure drop, which is beneficial to CBM desorption and enhances reservoir productivity. The increment of pressure drop from 5.37 MPa2 to 8.66 MPa2 leads to an increase of CBM production from 3270 m3/d to 6700 m3/d and is attributed to a decrease in BHP from 2.25 MPa to 1.33 MPa.展开更多
苏里格气田东区北部上古生界气藏原始压力系数低,并且随采出程度的增加目前地层压力系数降低至0.4,因该区域经压裂改造后的水平井对井筒沉积物清理过程中有较高的储层保护和工艺安全要求,常规的冲砂、清砂工艺存在局限性。借鉴水平井欠...苏里格气田东区北部上古生界气藏原始压力系数低,并且随采出程度的增加目前地层压力系数降低至0.4,因该区域经压裂改造后的水平井对井筒沉积物清理过程中有较高的储层保护和工艺安全要求,常规的冲砂、清砂工艺存在局限性。借鉴水平井欠平衡钻井和吐哈油田直井氮气钻磨桥塞的成功案例,以Boyun Guo和Ali Ghalambor等人的研究结果为基础,建立了井底流压、固相携带能力、施工压力和井口流速4种数学模型,并基于数学模型的计算和预测结果,于2023—2024年在苏里格气田试验应用连续油管气液混相钻冲砂6井次,单井日增气均超过2.5×104 m 3/d。试验井的随钻电子压力计数据结果显示,实测井底流压值与理论计算结果吻合,证实井底流压计算核心数学模型的准确可靠。该研究为同类井解堵增产提供了一种全新的解决方法。展开更多
基金part of a key project carried out in 2009–2010financially supported by the National Key Sci-Tech Major Special Item (Grant No. 2009ZX05038)
文摘A method is proposed to predict the flowing bottomhole pressures （FBHPs） for two-phase coalbed methane （CBM） wells. The mathematical models for both gas column pressure and two-phase fluid column pressure were developed based on the well liquid flow equation. FBHPs during the production were predicted by considering the effect of entrained liquid on gravitational gradients. Comparison of calculated BHPs by Cullender-Smith and proposed method was also studied. The results show that the proposed algorithm gives the desired accuracy of calculating BHPs in the low- productivity and low-pressure CBM wells. FBHP is resulted from the combined action of wellhead pressure, gas column pressure and fluid column pressure. Variation of kinetic energy term, compressibility and friction factors with depth increments and liquid holdup with velocity should be considered to simulate the real BHPs adequately. BHP is a function of depth of each column segment. The small errors of less than 1.5% between the calculated and measured values are obtained with each segment within 25 m. Adjusting BHPs can effectively increase production pressure drop, which is beneficial to CBM desorption and enhances reservoir productivity. The increment of pressure drop from 5.37 MPa2 to 8.66 MPa2 leads to an increase of CBM production from 3270 m3/d to 6700 m3/d and is attributed to a decrease in BHP from 2.25 MPa to 1.33 MPa.
文摘苏里格气田东区北部上古生界气藏原始压力系数低,并且随采出程度的增加目前地层压力系数降低至0.4,因该区域经压裂改造后的水平井对井筒沉积物清理过程中有较高的储层保护和工艺安全要求,常规的冲砂、清砂工艺存在局限性。借鉴水平井欠平衡钻井和吐哈油田直井氮气钻磨桥塞的成功案例,以Boyun Guo和Ali Ghalambor等人的研究结果为基础,建立了井底流压、固相携带能力、施工压力和井口流速4种数学模型,并基于数学模型的计算和预测结果,于2023—2024年在苏里格气田试验应用连续油管气液混相钻冲砂6井次,单井日增气均超过2.5×104 m 3/d。试验井的随钻电子压力计数据结果显示,实测井底流压值与理论计算结果吻合,证实井底流压计算核心数学模型的准确可靠。该研究为同类井解堵增产提供了一种全新的解决方法。
