元坝气田超深层生物礁气藏产水类型识别与开发对策
Classification and develoment countermeasures on water production in extradeep bioreef gas reservoirs, Yuanba gasfield, Sichuan Basin
任世林 徐守成 杨 杰 张小青
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作者单位：中国石化西南油气分公司勘探开发研究院
中文关键字：元坝气田 碳酸盐岩 生物礁 产水类型 开发对策
英文关键字：Yuanba gasfield; Carbonate rock; Bioreef; Water-producing type; Development countermeasure
中文摘要： 元坝气田是一个以孔隙为主、局部发育裂缝（溶孔）的碳酸盐岩礁滩相气藏，礁、滩内部非均质性很强，形成“一礁一藏”“一滩一藏”的气藏分布模式，气藏气水关系复杂，不同礁滩体具有独立的气水系统，水体主要分布在东区。制定产水井出水类型判别方法对于不同类型产水区合理高效治水具有现实意义。通过采出程度和水气比双对数曲线法、出水累计天数和水气比半对数曲线法，在100 余组压汞实验数据的基础上，划分产水井类型并提出了相应的开发对策。结果表明：①产水气井的类型划分为“溶孔+ 裂缝”“裂缝+ 孔隙（溶孔）”“ 裂缝+ 溶孔”“网状裂缝”型4 类；②“ 溶孔+ 裂缝”型的水侵特征为无水采气期可持续至采出程13% 左右，平均水气比较小，“ 裂缝+ 孔隙（溶孔）” 型的无水采气期可持续至采出程度9% 左右，产水量相对较小，平均水气比较小，“裂缝+ 溶孔”型的无水采气期较短、平均水气比较大，网状裂缝型基本没有无水采气期，产水量急剧增大、平均水气比大；③针对不同类型的产水井，提出了“低位排水、高位控制”“分类控水”“低排低采、低排高采”“封堵水层、排水采气”“水资源回用”5 项控水治水开发对策。实践证明通过不同礁带产水井分类控水使产水气井保持了稳定的日均产气量。
英文摘要： Yuanba gasfield, Sichuan Basin, is also as carbonate gas reservoirs of bioreef and beach facies, in which are mainly developed with pores and partly fractures (dissolved pores). Moreover, it's found quite strong heterogeneity inside bioreef and beach. And two models of reservoir distribution, including one model of "one bioreef one gas reservoir" and another model of "one beach one gas reservoir" are formed. These reservoirs are characterized by complex gas-water relationship and an independent gas-water system developed in each bioreef and beach body. Most waterbody is distributed in the eastern gasfield. Therefore, to develop a method of discriminating water-producing type for these water-producing gas wells is of practical significance to reasonable and efficient water control of various types of water-producing areas. So, based on over 100 sets of mercury-intrusion test data, all water-producing gas wells were classified by means of log-log method of both recovery degree and water/gas ratio, and semi-log method of both cumulative water-producing day and water/gas ratio. Moreover, several corresponding countermeasures were proposed. Results show that (1) these water-producing gas wells can be classified into four types, such as "dissolved pore + fracture" type, "fracture + pore (dissolved pore)" type, "fracture + dissolved pore" type, and "network fracture" type; (2) for the “dissolved pore + fracture" type, the water invasion presents some characteristics that a water-free gas-producing period may last until a recovery degree reaches about 13% and an average water/gas ratio is lower. As for the "fracture + pore (dissolved pore)" type, the water-free gas-producing period lasts until the recovery degree reaches about 9%, the water-producing rate is lower, and the average water/gas ratio is also lower. As for the “fracture + dissolved pore” type, the water-free gas-producing period is shorter and the average water/gas ratio is higher. And as for the "network fracture" type, there is basically no water-free gas-producing period, and the water-producing rate increases sharply and the average water/gas ratio is high; and (3) five water-control countermeasures are made, including "water drainage at lower position and water control at higher position", "classified water control", "drainage and production at lower position, and drainage at lower position and production at higher position", "plugging water layer and drainage gas recovery", and "water resource recycle". It's practically proved that for the water-producing gas wells located at different bioreef belts, an average daily gas production can be kept stable by
conducting the classified water control.