Sandstone matrix acidizing knowledge and future development

Abstract

To meet rising global demands for energy, the oil and gas industry continuously strives to develop innovative oilfield technologies. With the development of new enhanced oil recovery techniques, sandstone acidizing has been significantly developed to contribute to the petroleum industry. Different acid combinations have been applied to the formation, which result in minimizing the near wellbore damage and improving the well productivity. A combination of hydrofluoric acid and hydrochloric acid (HF:HCl) known as mud acid has gained attractiveness in improving the porosity and permeability of the reservoir formation. However, high-temperature matrix acidizing is now growing since most of the wells nowadays become deeper and hotter temperature reservoirs, with a temperature higher than 200°F. As a result, mud acid becomes corrosive, forms precipitates and reacts rapidly, which causes early consumption of acid, hence becoming less efficient due to high pH value. However, different acids have been developed to combat these problems where studies on retarded mud acids, organic-HF acids, emulsified acids, chelating agents have shown their effectiveness at different conditions. These acids proved to be alternative to mud acid in sandstone acidizing, but the reaction mechanism and experimental analysis have not yet been investigated. The paper critically reviews the sandstone acidizing mechanism with different acids, problems occurred during the application of different acids and explores the reasons when matrix stimulation is successful over fracturing. This paper also explores the future developing requirement for matrix acidizing treatments and new experimental techniques that can be useful for further development, particularly in developing new acids and acidizing techniques, which would provide better results and information of topology, morphology and mineral dissolution and the challenges associated with implementing these ''new'' technologies.

Investigation of change in different properties of sandstone and dolomite samples during matrix acidizing using chelating agents

“…Acidizing is a process in which injected fluid (mainly acid) in porous media reacts with matrix/minerals. This may lead to the variation in permeability and porosity due to the dissolution of rock minerals and re-precipitation of reaction products (Shafiq and Mahmud 2017).…”

Introductory Chapter: Developments in the Exploitation of Unconventional Hydrocarbon Reservoirs

“…This is the injection of acids into a reservoir to dissolve the rock matrix. Dissolution of portions of the rock creates wormholes while increasing its permeability and porosity [13]. Acid fracturing and matrix acidisation are the two main acidisation methods adopted as stimulation techniques [14].…”

“…limestone, dolostone and carbonate-rich shale) and silicate-rich rocks (e.g. sandstone) are soluble in HCL and HF, respectively [13,27]. Most formation rocks are not exclusively one or the other; therefore, in many instances, an acid blend (mud acid) comprising a combination of more than one type of acid is used.…”

A preliminary screening and characterization of suitable acids for sandstone matrix acidizing technique: a comprehensive review

“…In general, the procedures of experiment and results from these literature studies have provided an important insight and some constructive outlooks for the experimental work or simulation design and setup that are worth technical investigation in the future. As highlighted by Shafiq and Mahmud (2017), the future of matrix acidizing should focus on solving the problems associated with high temperature. New acid combinations developed are expected to not only improve the permeability, but also reduce the precipitation effect.…”