Performance Comparison of New Combinations of Acids with Mud Acid in Sandstone Acidizing

Abstract

The aim of this research is to find the best suitable acid to acidize undamaged low permeable sandstone formation Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50 to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration) and the design (Pre-flush, Main Acid, After-flush) is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid-Hydrofluoric with Concentration (3% HF-12% HCl). This study presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results analyzed are porosity, permeability, strength, color change and FESEM Analysis. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.

Myristic acid based imidazoline derivative as effective corrosion inhibitor for steel in 15% HCl medium

“…production or recovery of hydrocarbons from depleted wells. In this practice, hydrochloric acid solution in the concentration range of 15-32% (depending on whether the formation rock is made of sandstone or limestone) is force down a well bore to etch the formation rocks and create larger flow channels [1][2][3][4]. As it is known, HCl is corrosive hence corrosion of oil well metallic structures is inevitable.…”

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

“…The research group in recent years led by Shafiq et al presented multiple experimentations using various acid combinations (Shafiq et al 2013b(Shafiq et al , 2014Shafiq and Shuker 2013;Shafiq et al 2015;Shafiq and Ben Mahmud 2016). The acid combinations tested by the authors included a mixture of orthophosphoric (H 3 PO 4 ) acid and HF; fluoroboric (HBF 4 ) acid and HCOOH; and HCOOH and HF.…”

Sandstone matrix acidizing knowledge and future development

“…In comparison with mud acid, phosphonic-based HF acid system shows significantly better performance of permeability enhancement of 177.86% at 300°F. Shafiq et al (2015), Shafiq and Mahmud (2016) and Shafiq et al (2014) performed experimental study with The Berea sandstone core samples were reacted with these acid combinations and analyzed in terms of the porosity, permeability, mineralogy, pH change and strength. According to the findings, although all these acid combinations can be used as the main acid in sandstone acidizing, yet the best acid combination is 3%HF:9%H 3 PO 4 .…”

“…These acids also possessed some problems similar to mud acid like fast reaction rates and formation of precipitates. , Shafiq et al (2014) used organic mud acid to acidize sandstone formation in comparison with mud acid and presented their results in terms of acid pH value change. The results revealed that the pH value change after the acidizing is not much when organic mud acid is used as compared to standard mud acid, and this change is even less when fluoboric acid was added in place of hydrofluoric acid.…”