Estimation method of heterogeneous sulfur saturation distribution in high sulfur content gas reservoirs based on well test data

• Published in: Environmental earth sciences Vol. 82; no. 4; p. 115
• Main Authors: Liu, Xianshan, Liu, Shudong, Wang, Yang, Xiang, Yi, Qing, Chun, Zhang, Hang, Ren, Hongming, Li, Chengyong
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2023; Springer Nature B.V
• Subjects: Algorithms; Biogeosciences; Deposition; Distribution; Dynamic analysis; Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; Exploitation; Gas production; Gas wells; Geochemistry; Geology; Hydrology/Water Resources; Methods; Oil and gas fields; Oil and gas production; Original Article; Permeability; Perturbation theory; Pressure drop; Production methods; Reservoirs; Saturation; Seepage; Simulators; Sulfur; Sulfur content; Sulfur deposition; Sulphur; Terrestrial Pollution; Weighting functions; Inverse solution algorithm (ISA); Well-testing; Sulfur saturation estimation; High sulfur content; Sour gas reservoirs
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-023-10788-4

Sulfur deposits exist during the exploitation of high sulfur content gas reservoirs, which may reduce the permeability in the reservoir and accelerate the decline of gas production. Existing methods can only be used to estimate the average value of sulfur saturation, not the distribution of heterogeneous sulfur saturation. To this end, in this study, a radial heterogeneous seepage model is established, and the pressure solution in Laplace space is solved using Laplace and Perturbation theory, which is transformed into real space using a numerical inversion algorithm. The instantaneous sulfur saturation with a weighting function is redefined. Based on this, an inverse solution algorithm (ISA) is derived, which can be used to estimate the distribution of heterogeneous sulfur saturation from well-test data. The validity and reliability of the method were verified by a commercial simulator. P4 well is a typical high-sulfur gas well in China's P gas field, and the sulfur saturation and permeability in the reservoir near this well were estimated by ISA. The results show that the reservoir permeability is severely damaged by sulfur deposition located in the reservoir within 5 m near P4 well, where the pressure drop and sulfur deposition are high, and the sulfur saturation is as high as 30–40%. Overall, the proposed ISA facilitates accurate dynamic analysis in high sulfur-content gas reservoirs and provides a basis for preparing stimulation measures in areas contaminated by sulfur deposition.