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

Abstract

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.

Sodium fatty alcohol polyoxyethylene ether carboxylate/cationic surfactant binary system for high‐salt oil reservoir

“…But other composite systems such as AECM–CTAB (7:3) did not show enhanced properties; their contact angle was 95.37° and they were still in the lipophilic surface, while this composite system was still able to achieve ultralow interfacial tension. Wettability and interfacial tension have no direct relationship, and the strength of wettability is related to a variety of factors that have been studied (Alqam et al, 2021; Bhutto et al, 2023; Lu et al, 2017; Zhang et al, 2018). Therefore, it is not effective to improve recovery by reducing the interfacial tension alone.…”

Wettability Alteration of Limestone Carbonate Cores Using Methylene Blue and Alumina-Based Nanofluid: Implications for EOR

“…The experimental setup consisted of three main components, which included a light source, sample placing stage, and a camera for image recording. Details of the CA measurements were described in our previously published study [3]. CA measurements followed four basic steps, as describe below:…”

“…Fossil fuels are a significant contributor to the world energy demand [1][2][3][4][5]. It is reported that carbonate reservoir rock formations exhibit a high volume of about 60% of all the global reserves.…”

Assessment of the CO2 Geological Storage Potential of Yanchang Shale Gas Formation (Chang7 Member) Considering the Capillary Sealing Capability of Caprock

“…(3) The geological data and wellbore retained during the shale gas development process can be reused to lower the costs. (4) The injection of CO 2 can improve the recovery of CH 4 , which brings additional economic benefit [12][13][14][15][16][17][18][19][20]. In an earlier field experiment, CO 2 was injected into the Yanchang shale gas formation with the aim of increasing production.…”