Abstract
Stimulation of the sandstone reservoir requires a mixture of acids such as mud acid, which assist in enlarging the microscopic paths by dissolving the siliceous fines or clays near the well-bore region. As a result, the formation permeability and porosity can be enhanced. In deeper wells, the temperature exceeds 200 °F, at these temperature ranges, problems can arise. For example, the use of mud acid mixtures can lead to issues like precipitations, corrosion, early consumption of acids, leading to lesser acid efficiency. In this study, the core flooding apparatus was used for acidizing experiments, designed to dissolve minerals and to analyze the changes in petrophysical parameters such as porosity, permeability, and mineralogy. Conventional and tight sandstone core samples were acidized using different chelating acids such as Hydroxyethylethylenediaminetriacetic acid (HEDTA), Ethylenediaminetetraacetic acid (EDTA) and Glutamic acid (GLDA) at high-temperature conditions. Analytical studies (mineral mass, pore size distribution, topology, grain size distribution, and density distribution were conducted using Tescan Integrated Mineral Analysis (TIMA). The obtained results showed that chelating agent HEDTA created more pore spaces in the core samples and is effective in dissolving positive ions. Also, the permeability was observed to be doubled by its application which could be effective in alteration of pore topology of the sandstone cores.
Highlights
Sandstone is a clastic sedimentary rock, primarily made up of quartz and minor cementing minerals such as quartz, feldspar, various forms of clays and carbonates (Shafiq et al 2018c), which can acquaint with severe damage if introduced to incompatible fluids
Hydroxyethylethylenediaminetriacetic acid (HEDTA) proved to be efficient in increasing the porosity of Berea sandstone samples where the increment is about 6.8% from the original porosity followed by GLDA at 5.8%
The study presented the behavior of different chelating agents reacting with different types of sandstones
Summary
Sandstone is a clastic sedimentary rock, primarily made up of quartz and minor cementing minerals such as quartz, feldspar, various forms of clays and carbonates (Shafiq et al 2018c), which can acquaint with severe damage if introduced to incompatible fluids. Sandstone acidizing is a heterogeneous acid-rock process; the selection of acid mixture is critical. Improper selection of acid and acid treatment will further damage the formation rather than. Especially in a high-temperature condition in the reservoir (Shafiq and Ben Mahmud 2017). Reservoir rocks are stimulated by acid injection below the fracture pressure of the formation. The injection of the acid in the sandstone layers will cause the dissolution of the minerals in the formation, increasing the flow rate of the reservoir fluid (Mahmud and Leong 2017; Leong et al 2018)
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