Distribution and Main Controlling Factors of Gas and Water in Tight Sandstone Gas Fields: A Case Study of Sudong 41-33 Block in Sulige Gas Field, Ordos Basin, China

Tong Xu; Ailin Jia; Yougen Huang; Shixiang Fei; Zhi Guo; Dewei Meng; Naichao Feng; Ruohan Liu; Chenhui Wang; Suqi Huang

doi:10.1021/acsomega.3c09154

Distribution and Main Controlling Factors of Gas and Water in Tight Sandstone Gas Fields: A Case Study of Sudong 41-33 Block in Sulige Gas Field, Ordos Basin, China

ACS Omega. 2024 May 6;9(19):20807-20818. doi: 10.1021/acsomega.3c09154. eCollection 2024 May 14.

Authors

Tong Xu¹, Ailin Jia¹, Yougen Huang², Shixiang Fei², Zhi Guo¹, Dewei Meng¹, Naichao Feng¹, Ruohan Liu¹, Chenhui Wang¹, Suqi Huang¹

Affiliations

¹ Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China.
² Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710018, China.

Abstract

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 CaCl₂ 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 P₂x_8-1, P₂x_8-2, and P₁s₂ 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.