A New Method To Evaluate Reaction Kinetics of Acids with Carbonate Rocks Using NMR Diffusion Measurements

Abstract

In this work, a new method to evaluate the reaction kinetics of different stimulation fluids with carbonate rocks was introduced. NMR diffusion measurements were used to determine the acid diffusion coefficient and the acid tortuous path inside carbonate rocks. Reaction kinetics can also be evaluated using rotating disk apparatus (RDA) in which a disc is rotated in the bulk fluid at different rotational speeds. RDA does not represent the actual, restricted acid diffusion that takes place in the porous media because only the surface of the rock is exposed to the reaction and the acid is not confined in the porous media. NMR diffusion measurements can accurately describe and determine the acid restricted diffusion in porous media. The diffusion coefficient of the acid is a crucial term in describing the reaction kinetics of acids with carbonate rocks. It is also used to predict the optimum injection rate required during the acidizing treatment and the soaking time for different fluids required to remove scales and deposits in the wellbore. The restricted diffusion was determined for different fluids such as GLDA chelating agent, HEDTA chelating agent, and EDTA chelating agent. Core flooding experiments for each fluid were conducted to determine the optimum injection rate. NMR restricted diffusion measurements then were conducted to determine the restricted diffusion and in turn to determine the optimum injection rate. The optimum injection rate estimated from the NMR was compared to that from the core flooding experiments. The results were a good match showing that NMR is a suitable, reliable, and robust method to evaluate reaction kinetics of different fluids with carbonate rocks.

Applications of Chelating Agents in the Upstream Oil and Gas Industry: A Review

“…It showed lower removal efficiency compared to EDTA and DTPA at the same conditions. , The NTA chelating agent was also effective in removing the filter cake formed by calcite water- and oil-based drilling fluid in 24 h of soaking time . A polyacidic chelate (NPC) breaker was developed to dissolve the filter cake formed by calcite drilling fluid …”

“…123 A polyacidic chelate (NPC) breaker was developed to dissolve the filter cake formed by calcite drilling fluid. 124 Overall, chelating agent solutions show high performance in different applications of filter cake cleanup processes. Table 4 summarizes the solubility of filter cake in different types of chelating agents.…”

Review of Acid Diffusion Measurement Methods in Porous Media

“…A higher Δ value is recommended so that the diffusing molecules experience the geometrical restrictions of the confining space. Elsayed et al 26 proposed a new model that replaces the heterogeneity factor in the equation by Mahmoud and Nasr-El-Din. 54 with diffusive tortuosity.…”

“…Currently, the study conducted by Elsayed et al 26 was the only one that suggested measuring the diffusion coefficient of a weak acid using NMR. The measurement was carried out using the approach proposed by Zecca et al 66 and Cott et al 67 The approach was originally used to measure the self-diffusion of nonreactive fluids.…”

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

“…Moreover, special core analysis (SCA) experiments such as wettability, capillary pressure, and clay minerals analysis can be determined using NMR (Al-Garadi et al 2022;Connolly et al 2017;Elsayed et al 2020a;Freedman et al, 2003a;Newgord et al 2020;Tandon et al 2020;Tandon and Heidari 2018;Worden and Morad 1999). Numerous EOR methods including acid and fracture stimulation, thermochemical fluids for gas condensate removal, miscible gas injection (huff 'n' puff), CO 2 injection, and thermal-EOR have been evaluated with the use of different NMR measurements (Adebayo et al 2020a, b;Chen et al 2018a, b;Dang et al 2019;Elsayed et al 2021bElsayed et al , 2020bHassan et al 2020;Mukhametdinova et al 2020). Drilling and production and engineering operation issues are also addressed in the literature.…”