Carbonate Acidizing: Modeling and Uncertainty Propagation Analysis

  • Qasim Sahu

Student thesis: Master's Thesis

Abstract

Reservoir stimulation is a common technique used to improve the productivity of carbonate reservoirs. One of the effective stimulation methods is carbonate acidizing. This process involves injecting a reactive fluid to dissolve the rock mineral, creating a conductive path for hydrocarbon flow. With the development of tight and unconventional reservoirs, stimulation has become more critical for optimal economic production. This study aims to simulate the dissolution of carbonate in matrix acidizing. A reactive transport model is implemented in a finite – element solver to simulate the initiation and propagation of the dissolution channel in the carbonate rock in a two – dimensional domain. We investigate the effect of varying the injection rate on the dissolution channel and the efficiency of the acidizing fluid. Next, we use polynomial chaos expansion to conduct uncertainty propagation analysis. These uncertainties may have a major impact on the predictability of the simulation model. We utilize the surrogate model and Sobol indices to identify the most significant parameter in the model. The analysis provides an assessment of how the uncertainty can propagate to the model’s response. Also, we utilize the surrogate model to calculate the univariate effect. The results showed that the dissolution channel and pore volume to breakthrough depends on the injection rate. Furthermore, the surrogate model reproduces the simulation model results for the 5 dissolution channel, the pore volume to breakthrough, and the effective permeability. The global sensitivity analysis shows that the acid capacity number is the most significant parameter for the pore volume to breakthrough with the highest Sobol index value. For effective permeability, the initial mean porosity is the primary source of uncertainty. The marginal effect calculated for the individual parameter correlates with the results from Sobol indices.
Date of AwardJul 2021
Original languageEnglish (US)
Awarding Institution
  • Physical Science and Engineering
SupervisorHussein Hoteit (Supervisor)

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