天然气工业2018，Vol.38Issue(5)：77-86,10.DOI:10.3787/j.issn.1000-0976.2018.05.009
致密砂岩气藏近井地带含水饱和度变化规律
Change of water saturation in tight sandstone gas reservoirs near wellbores
摘要
Abstract
Tight sandstone gas reservoirs commonly contain water, so liquid loading often appears near wellbores, leading to production decline and even shutdown of gas wells. Therefore, the study on the change of water saturation near wellbores is of great significance to understanding the water production mechanisms of gas wells. In this paper, a set of physical simulation experiment procedures of identifying the change of water saturation near wellbores was designed according to the principle of radial well seepage of gas wells, and the production performance after vertical well fracturing in gas reservoirs was simulated by connecting tight cores with a diameter of 10.5 cm, 3.8 cm and 2.5 cm in series in a descending order of distance. According to the depressurizing production mode of gas wells, tubes with small diameters of 20, 30, 40 and 50 μm were used to simulate gas well tubing to control the gas production rate. And the change of water saturation near wellbore in the process of depletion production and its influencing factors were investigated. Finally, combined with actual data of production wells, the water saturation and water production of gas wells near wellbores and in different zones were calculated at the above four different small diameters of tubes and the changes thereof were also analyzed. The following results were obtained. First, each gas production rate corresponds to a critical water saturation. When the initial water saturation is lower than the critical value, the formation water flowing near the wellbore and in the middle zone can be carried out along with the production of gas and no liquid loading is formed. Second, when the initial water saturation is higher than the critical value, a large amount of formation water migrating from the distal zones accumulates near the wellbore, and thus liquid loading occurs at the bottom hole. Third, when the initial water saturation is equal to the critical value, the higher the gas production rate is, the more easily liquid loading tends to form near the wellbore. Fourth, for the same water saturation, water production increases and recovery factor decreases with the increase of gas production rate. In conclusion, the cumulative water production chart of a gas well generated by the physical simulation experiment method proposed in this paper agrees well with the water production behavior of the corresponding gas well. The research results are conducive to the effective prediction of gas well water production and can be used as guidance for the reasonable gas well water control.关键词
致密砂岩气藏/近井地带/含水饱和度/微管直径/平面径向渗流/物理模拟实验/气井产水量/采气速率/治水措施Key words
Tight sandstone gas reservoir/Near the wellbore/Water saturation/Tube with a small diameter/Plane radial seepage/Physical simulation experiment/Water production rate of gas well/Gas production rate/Water control引用本文复制引用
马宏煜,张春秋,高树生,叶礼友,刘华勋,熊伟,史江龙,王霖,吴康,祁青山..致密砂岩气藏近井地带含水饱和度变化规律[J].天然气工业,2018,38(5):77-86,10.基金项目
国家科技重大专项"裂缝—孔洞型储层空间特征及渗流规律实验评价" (编号:2016ZX05052-002-001) （编号:2016ZX05052-002-001）
国家科技重大专项"裂缝孔隙 (洞) 型边底水气藏水侵机理及对气藏稳产能力和采收率影响" (编号:2017ZX05030-003-003-001) （洞）
中国石油天然气股份有限公司科学研究与技术开发项目 (编号:2016B-1501). （编号:2016B-1501）
