TY - THES

T1 - Screening of organic acids suitable for stimulation treatments

AU - Derler, Markus

N1 - no embargo

PY - 2018

Y1 - 2018

N2 - Carbonate formations are stimulated since decades with the use of hydrochloric acid (HCl) based fluids due to the cost advantage and the high dissolving power. This stimulation design is associated with two distinctive drawbacks in high temperature formations. First, HCl has a high reaction rate with carbonate rocks that limits its penetration into the formation and second, its high corrosion rate. As a result, weaker acids becomes a viable alternative to mitigate these drawbacks. The purpose of this study is to gain an understanding of the reaction behavior of weaker acids with carbonate rocks, to evaluate their corrosion behavior and prove their applicability. Possible candidates were identified by screening selected acid parameters. The screening process mainly concentrated on organic acids, but other promising acid opportunities were also investigated. The dissolution and corrosion behavior of selected acids were compared equimolar to a 10% HCl solution at different temperatures. Dolomite and limestone samples were used for the dissolving study and samples of the spent acid were periodically collected to measure calcium and magnesium concentrations using ion chromatography. The ion concentration was used to determine and study the acid-mineral reaction behavior. The corrosion study was performed using low carbon steel samples and the corrosivity was determined via mass loss. The results of the dissolution experiment show that weak organic acids do not fully dissociate and therefore cannot dissolve the same amount of carbonate which HCl can dissolve. It also shows that a higher temperature leads to a higher reaction rate. In the corrosion experiment, the weak organic acid showed a lower mass loss and corrosion rate than HCl. The strong organic acids showed a higher mass loss and a higher corrosion rate compared to HCl.

AB - Carbonate formations are stimulated since decades with the use of hydrochloric acid (HCl) based fluids due to the cost advantage and the high dissolving power. This stimulation design is associated with two distinctive drawbacks in high temperature formations. First, HCl has a high reaction rate with carbonate rocks that limits its penetration into the formation and second, its high corrosion rate. As a result, weaker acids becomes a viable alternative to mitigate these drawbacks. The purpose of this study is to gain an understanding of the reaction behavior of weaker acids with carbonate rocks, to evaluate their corrosion behavior and prove their applicability. Possible candidates were identified by screening selected acid parameters. The screening process mainly concentrated on organic acids, but other promising acid opportunities were also investigated. The dissolution and corrosion behavior of selected acids were compared equimolar to a 10% HCl solution at different temperatures. Dolomite and limestone samples were used for the dissolving study and samples of the spent acid were periodically collected to measure calcium and magnesium concentrations using ion chromatography. The ion concentration was used to determine and study the acid-mineral reaction behavior. The corrosion study was performed using low carbon steel samples and the corrosivity was determined via mass loss. The results of the dissolution experiment show that weak organic acids do not fully dissociate and therefore cannot dissolve the same amount of carbonate which HCl can dissolve. It also shows that a higher temperature leads to a higher reaction rate. In the corrosion experiment, the weak organic acid showed a lower mass loss and corrosion rate than HCl. The strong organic acids showed a higher mass loss and a higher corrosion rate compared to HCl.

KW - Stimulation

KW - Säuerung

KW - Produktionsstimulation

KW - Karbonatsäuerung

KW - Sondenstimulation

KW - Sondenbehandlung

KW - stimulation

KW - acid stimulation

KW - production optimization

KW - acidizing

KW - matrix acidizing

KW - carbonate acidizing

KW - screening of organic acids

M3 - Master's Thesis

ER -