Characteristics of Shale Wettability by Contact Angle and Its Influencing Factors: A Case Study in Songliao

Xue, Haitao; Dong, Zihan; Tian, Shansi; Lu, Shuangfang; An, Ce; Zhou, Yuan; Li, Boheng; Xin, X. B.

doi:10.3389/feart.2021.736938

Cited by 9 publications

(1 citation statement)

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“…For the exploitation and development of efficient oil and gas reservoirs, wettability plays the most significant role and controls the fluid flow, as well as affects the productivity of the reservoirs. − It is commonly held that wettability is a physiochemical parameter that depends on the fluid–rock interactions, total organic content (TOC), interfacial tension, thermal maturity, mineral compositions, and surface roughness and rock physical properties. − Thus, the wettability of shales is affected by various parameters from the presence of organic matter, rock composition, to mineral–grain orientations. However, shales are not fully characterized in terms of their wettability characteristics.…”

Section: Introductionmentioning

confidence: 99%

Shale Wettability Characteristics via Air/Brines and Air/Oil Contact Angles and Influence of Controlling Factors: A Case Study of Lower Indus Basin, Pakistan

et al. 2022

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Wettability is the fundamental parameter that influences the productivity of hydrocarbon reservoirs. The knowledge of this regarding shale formation is yet inadequate; thus, detailed analysis is essential for successful development of such reservoirs. The Early Cretaceous Sembar formations in the Lower Indus Basin, Pakistan, is considered as the key target for energy exploration; however, it exhibits large uncertainties due to the lack of data availability. Sembar shales hold significant hydrocarbon volumes rich in organic content; however, prior to this, no comprehensive research has been conducted to quantify the wetting behavior of these shales. Thus, precise information about the wetting behavior of Sembar shale formations is essential, as it is influenced by many factors. Therefore, in this study, we examined the wettability of Sembar shale samples by performing a suit of contact angle (CA) measurements. The CA measurements on shale samples were performed using different salt types (NaCl, KCl, MgCl2, and Reef Salt) and concentrations of 0.1 M and 0.5 M under ambient pressures and varying temperatures (25–50 °C). The CA was measured via air–brine and air–oil under prevailing pressure and temperature conditions. Subsequently, the sample morphology and surface topography were examined via field emission scanning electron microscopy and atomic force microscopy, respectively. The mineral compositions were obtained via X-ray diffraction studies. The results clearly show that the Sembar shale possesses a mixed wetting behavior. Under dry surfaces, they have large affinity to oil and deionized water in which the droplet spreads quickly on the sample surfaces. Conversely, the samples aged with n-decane and NaCl brines exhibited higher CAs than the untreated samples. Additionally, the CA measured by changing temperatures led to an increase for all brine droplets; the CA further increased as the concentrations of salts increased from 0.1 to 0.5 M. We then discussed the possible reasons for the discrepancy in CA values due to temperature changes and brine concentrations. Moreover, the CA was measured corresponding to the surface roughness from which it appears that it merely affects the wettability of these shale samples. However, the present study results lead to an improved understanding of the wettability of Sembar shale of the Lower Indus Basin in Pakistan.

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