Acidizing of conventional and tight sandstone formation using chelating agents: mineralogical prospect
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ORIGINAL PAPER--PRODUCTION ENGINEERING
Acidizing of conventional and tight sandstone formation using chelating agents: mineralogical prospect Mian Umer Shafiq1,2 · Hisham Ben Mahmud2 · Sophia Nawaz Gishkori3 · Kiat Moon Lee4 · Reza Rezaee5 Received: 3 February 2020 / Accepted: 15 June 2020 © The Author(s) 2020
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. Keywords Stimulation · Mineralogy · Chelating agent · Sandstone · Petrophysical
Introduction 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; therefore, the selection of acid mixture is critical. Improper selection of acid and acid treatment will further damage the formation rather than * Mian Umer Shafiq [email protected] 1
NFCIET, Multan, Opposite Pak Arab Refinery, Khanewal Road, Multan, Pakistan
2
Curtin University, Malaysia, CDT 250, 98009 Miri, Sarawak, Malaysia
3
University of Gujrat, Gujrat, Pakistan
4
UCSI University, Kuala Lumpur, Malaysia
5
Curtin University Australia, Kent Street, Bentley, WA, Australia
improving it, especially in a high-temperature condition in the reservoir (Shafiq and Ben Mahmud 2017). Illite/smectite, for example, a component of clay, swells when contacted with freshwater and can reduce the permeability and porosity of the rock effectively. Reservoir rocks are stimulated by acid injection below the fracture pressure of the formation. The in
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