煤层气井无杆排采工艺应用与改进方向

鄂尔多斯盆地东缘地区煤层气资源量巨大，现已成为我国煤层气主力产区之一。区块自开发以来，针对中浅层煤层大斜度井与水平井开展了液力无杆泵、水力射流泵、电潜泵、隔膜泵排采工艺试验，生产中发现上述4类无杆排采工艺具有能有效避免大斜度井与水平井管杆偏磨的优点，但同时存在防煤粉防砂能力一般、防腐蚀防垢能力一般，存在高压刺漏风险、下泵深度受限、地面设备可靠性不强等缺点。通过分析区块前期中浅层煤层气井无杆排采工艺试验效果，总结了各类无杆排采工艺的优缺点，并指出中浅层煤层气井无杆排采工艺的改进方向。目前，随着煤层气勘探开发领域由中浅层煤层逐步转向深层煤层，原有中浅层煤层气井无杆排采工艺已无法满足深层煤层气井的排水采气需求，针对深层煤层气 “原生结构煤发育、地层压力高、高含气、高饱和、游离气与吸附气共存”的地质特征和 “见气早、气液比高”的生产特点，认为深层煤层气井无杆排采工艺需跳出中浅层煤层气井无杆排采工艺的思路，可以借鉴区块内致密气和海陆过渡相页岩气先导试验井的采气工艺经验，在生产现场开展“同心管气举”工艺、“小油管+泡排”工艺与“连续油管+柱塞+气举”工艺试验，能在有效避免传统无杆排采工艺缺点的同时实现深层煤层气的高效开发。 

Application and improvement directions of rodless drainage technology in coalbed methane wells: A case study from east margin of Ordos Basin

The eastern margin of Ordos Basin has a huge amount of coalbed methane resources, and has become one of the main coalbed methane producing areas in China. Since the development of the block, hydraulic rodless pump, hydraulic jet pump, electric submersible pump and diaphragm pump drainage and production process tests have been carried out for highly deviated wells and horizontal wells in medium shallow coal seam. During production, it is found that the above four types of rodless drainage and production processes have the advantages of effectively avoiding eccentric wear of pipes and rods in highly deviated wells and horizontal wells, however, they have general ability to prevent pulverized coal and sand, corrosion and scale and some disadvantages such as the risk of high-pressure puncture and leakage, the limited depth of lowering the pump, and the poor reliability of ground equipment. By analyzing the test results of rodless drainage technology of medium shallow coalbed methane wells in the early stage of the block, the advantages and disadvantages of various rodless drainage technologies are summarized, and the improvement direction of rodless drainage technology of medium shallow coalbed methane wells is pointed out. At present, as the exploration and development field of coalbed methane has gradually shifted from medium shallow coal seam to deep coal seam, the original rodless drainage and production process of medium shallow coalbed methane wells has been unable to meet the drainage and gas production demand of deep coalbed methane wells. In view of the geological characteristics of deep coalbed methane, such as “development of primary structure coal, high formation pressure, high gas content, high saturation, coexistence of free gas and adsorbed gas” and the production characteristics of “early gas breakthrough and high gas-liquid ratio”, it is considered that the rodless drainage process of deep coalbed methane wells needs to jump out of the rodless drainage process of medium shallow coalbed methane wells. We can learn from the gas production process experience of pilot test wells of tight gas and sea land transitional phase shale gas in the block, and carry out the tests of “concentric pipe gas lift”, “small tubing + bubble drainage” and “coiled tubing + plunger + gas lift” on the production site, which can effectively avoid the shortcomings of the traditional rodless drainage process and realize the efficient development of deep coalbed methane.