Xu Tong, Jia Ailin, Huang Yougen, Fei Shixiang, Guo Zhi, Meng Dewei, Feng Naichao, Liu Ruohan, Wang Chenhui, Huang Suqi
Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China.
Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710018, China.
ACS Omega. 2024 May 6;9(19):20807-20818. doi: 10.1021/acsomega.3c09154. eCollection 2024 May 14.
Studying the gas-water distribution characteristics is essential in guiding the efficient development of gas fields. The relationship between gas and water in the Sudong 41-33 Block is complicated and has not been adequately researched. In recent years, gas wells have suffered from increased water/gas ratios and significant liquid loadings, which greatly affect the development of the block. A comprehensive analysis of formation water, log interpretation, and production data was conducted to determine the gas-water distribution characteristics and main controlling factors in the Sudong 41-33 Block. The findings indicate the following. (1) The formation water in the study area consists mainly of CaCl brine with high total dissolved solids (TDS) (with an average value of 36.06 g/L). The hydrochemical characteristics indicate that the formation water is typical sedimentary buried water under well-sealing conditions, which is markedly different from shallow river water and seawater. (2) The formation water can be categorized into three types: edge-bottom water under the gas layer (Type I), stagnant water in tight sandstone (Type II), and isolated lenticular water (Type III). The water layer distribution in the plane is mainly concentrated in the northwest region, whereas it is dispersed in other regions. On the vertical, the water layer mainly appears in Px, Px, and Ps Members. (3) The physical properties of the reservoir, hydrocarbon generation intensity (HGI), source rock-reservoir relationship, and mini-structure are the main factors affecting the gas-water distribution in the study area. Based on the clarification of the characteristics of gas and water distribution and its main controlling factors, it is of great importance to accurately identify the water layer, avoid the direct development of the water layer, adopt the proper production pressure differential, and carry out drainage gas production measures in time to ensure the effective development of the gas field.
研究气水分布特征对于指导气田高效开发至关重要。苏东41-33区块气水关系复杂，尚未得到充分研究。近年来，气井出现水气比上升和严重积液现象，极大地影响了该区块的开发。通过对地层水、测井解释和生产数据进行综合分析，以确定苏东41-33区块的气水分布特征及主控因素。研究结果表明：（1）研究区地层水主要为高总溶解固体（TDS）（平均值为36.06g/L）的氯化钙型卤水。水化学特征表明，地层水是典型的封闭条件下的沉积埋藏水，与浅层河水和海水明显不同。（2）地层水可分为三种类型：气层下的边底水（I型）、致密砂岩中的滞流水（II型）和孤立透镜状水（III型）。水层在平面上的分布主要集中在西北部地区，而在其他地区则较为分散。在垂向上，水层主要出现在盒8、盒7和山西组段。（3）储层物性、生烃强度（HGI）、源储关系和微构造是影响研究区气水分布的主要因素。在明确气水分布特征及其主控因素的基础上，准确识别水层、避免水层直接开发、采用合适的生产压差并及时采取排水采气措施，对于确保气田有效开发具有重要意义。
