Numerical Simulation of the Acidizing Process and PVBT Extraction Methodology Including Porosity/Permeability and Mineralogy Heterogeneity

Oliveira, Thiago Judson Lima De; Melo, Andressa R. de; Oliveira, Joao Americo Aguirre; Pereira, Alexandre Zacarias Ignácio

doi:10.2118/151823-ms

Cited by 34 publications

(13 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, we need 3D numerical simulations to predict quantitatively the experimentally observed results. In the literature, a few 3D numerical studies (Cohen et al 2008;De Oliveira et al 2012;Ratnakar et al 2012Ratnakar et al , 2013Maheshwari et al 2013) have been performed recently to understand the dissolution process. However, these studies deal with slow-reacting acids and may not predict the results quantitatively for fast-reacting acids such as HCl.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Carbonate HCl Acidizing Experiments With 3D Simulations

Maheshwari

Balakotaiah

2013

SPE Production &Amp; Operations

View full text Add to dashboard Cite

Acidization of carbonate rocks is a common practice to reduce formation damage near the wellbore. In this process, an acidic solution is injected to dissolve some of the rock, creating conductive channels called wormholes. These wormholes facilitate the flow of hydrocarbons to the wellbore. In the literature, there are several theoretical and experimental studies performed to understand this process. Recent work by Maheshwari et al. 2013 focused on a qualitative comparison of 3D numerical results for slow-reacting acids with experimental data and presented a sensitivity analysis of the acidization process with respect to various transport, reaction, and rock properties. There are very few 3D numerical studies that can predict the experimental results quantitatively, such as the optimum injection rate for fast-reacting acids such as hydrochloric acid (HCl). Therefore, the main objective of this study is to quantitatively predict the experimentally observed acidization curve and dissolution patterns in carbonates with HCl.We present 3D numerical simulations of carbonate acidization with HCl using a two-scale continuum (TSC) model. The model describes the reactive transport at Darcy scale and retains all porescale physics through structure-property relations. Unlike previous studies, we use a new two-parameter (pore-broadening and poreconnectivity) structure-property relation to describe the change in permeability, pore radius, and interfacial area per unit volume with porosity. We predict quantitatively the experimentally observed acidization curve for an HCl/limestone system and show the existence of a critical heterogeneity (that corresponds to the minimum amount of acid required to breakthrough). We also present scaling criteria to estimate the wormhole-tip diameter and optimum acidinjection rate for vuggy and nonvuggy carbonates. Finally, we present the flow dynamics of acid inside the wormhole.

show abstract

Section: Introductionmentioning

confidence: 99%

Comparison of Carbonate HCl Acidizing Experiments With 3D Simulations

Maheshwari

Balakotaiah

2013

SPE Production &Amp; Operations

View full text Add to dashboard Cite

show abstract

“…The treatment tries to remove the near-wellbore damage without penetrating too deeply into the formation. This study focuses on matrix-acidizing experiments on carbonates, while following the aim of creating dominant wormholes with different acid systems (Berteux et al 1986;de Oliveira et al 2012).…”

Section: Basics In Theorymentioning

confidence: 99%

“…Finally, the data are summed up and correspond to a single conventional radio-frequency pulse excitation as long as no disturbing side effects take place. This allows faster imaging and recognition of short T 2 times or small pore sizes (Holmes and Bydder 2005;Tyler et al 2007;Du 2012).…”

Section: Experimental-test Proceduresmentioning

confidence: 99%

The First Visualization of Acid Treatments on Carbonates With 3D Nuclear-Magnetic-Resonance Imaging

et al. 2015

View full text Add to dashboard Cite

Carbonate reservoirs often show great heterogeneity in their inner rock structure, and stimulation treatments are often necessary to maintain or establish fluid production. Therefore, core-flow tests are usually conducted to test and model stimulation treatments within a laboratory scale to predict their performance. The visualization of wormholes that were created within core-flow tests requires novel technologies for evaluation and pathway-prediction purposes. Unfortunately, past visualization techniques were always associated with the destruction of the core sample, creating a demand for nondestructive methods.Nuclear-magnetic-resonance imaging (NMRI) is such a method that fulfills the approach of being nondestructive. The technology is widely known by medical applications, and this study developed a procedure on how to use the NMRI technology to visualize wormholes with NMRI in 3D.The study was started by initially choosing and obtaining various core samples that have different contents of calcite and dolomite. These core samples were imaged with the NMRI and microfocus-computed-tomography (mCT) technology in their unchanged state, and basic petrophysical experiments were conducted for initial experiments. The lCT technology was used as a reference visualization technique, because it provides a very high resolution with a corresponding high level of detail. Afterward, core-flow tests were conducted on the core samples with various acid systems and wormholes generated. Finally, the core samples with wormholes were imaged again with the NMRI and lCT technology, whereby the NMRI acquisition technique was improved toward imaging of rock samples, and the results were compared with the lCT results. The NMRI results showed moderate imaging achievements for the unchanged rock samples and high-quality imaging achievements for the extracted wormholes. IntroductionAcidizing applications are one of the most important stimulation strategies for carbonate reservoirs with low porosities and low permeabilities. Predicting the performance of such treatments is very difficult and normally performed with small-scale laboratory experiments in a core-flow tester. These experiments are evaluated by the measured parameters such as the used acid that was needed to create one or more wormholes through the core sample, but the wormhole pathway within the core sample is more difficult to identify. In the past, it was performed by techniques that destroyed the core sample by, for example, taking thin slices. One of the biggest disadvantages of conventional measures is thereby the mechanical destruction of the core samples, and damage to the wormhole structures themselves cannot be completely avoided.The nuclear-magnetic-resonance-imaging (NMRI) technology is already far developed through its medical applications and can be easily adapted from human/animal bodies toward rock

show abstract

“…This study focuses on matrix acidizing experiments on carbonates, while following the aim of creating dominant wormholes with different acid systems. (Berteux, Piot, & Thomas, 1986) (de Oliveira, Melo, Oliveira, & Pereira, 2012 The Nuclear Magnetic Resonance technology is based on two essential properties of atomic nuclei: The angular moment or spin that induces the net magnetic moment. The net magnetic moment property interacts with an applied static magnetic field B 0 and an oscillating magnetic field B 1 in such a way, that signals are produced and can be measured in consequence by an NMR machine.…”

Section: Basics In Theorymentioning

confidence: 99%

The First Visualization of Acid Treatments on Carbonates With 3D Nuclear Magnetic Resonance Imaging (NMRI)

Krebs

Lungwitz

Souza

et al. 2014

Day 2 Thu, February 27, 2014

View full text Add to dashboard Cite

Carbonate reservoirs with their high hydrocarbon potential show often a great heterogeneity in their inner rock structure, wherefore stimulation treatments are often necessary to maintain or establish fluid production. Therefore, core flow tests are usually conducted to test and model stimulation treatments within a laboratory scale in order to predict their performance. The visualization of wormholes that were created within core flow tests requires novel technologies for evaluation and pathway prediction purposes. Unfortunately, past visualization techniques were always associated with the destruction of the core sample and in that way, an increased demand raised in non-destructive methods.Nuclear Magnetic Resonance Imaging (NMRI) is such a method that fulfills the approach of being non-destructive. The technology is widely known by medical applications, but has never been used before in correlation with 3D rock imaging. Hence, this study developed a procedure on how to use the NMRI technology to visualize wormholes with NMRI in 3D.Therefore, a comprehensive study was started by initially choosing and obtaining various core samples that have different contents of calcite and dolomite. These core samples were imaged with the NMRI and µCT technology in their unchanged state as well as basic petrophysical experiments were conducted for initial experiments. The µCT technology was utilized as reference visualization technique, since it provides a very high resolution with a corresponding high level of detail. Afterwards, core flow tests were conducted on the core samples with various acid systems and wormholes generated. Finally, the core samples with wormholes were imaged again with the NMRI and µCT technology, whereby the NMRI acquisition technique was improved towards imaging of rock samples and the results were compared to the µCT results. The NMRI results showed moderate imaging achievements for the unchanged rock samples and high quality imaging achievements for the extracted wormholes.

show abstract

Numerical Simulation of the Acidizing Process and PVBT Extraction Methodology Including Porosity/Permeability and Mineralogy Heterogeneity

Cited by 34 publications

References 23 publications

Comparison of Carbonate HCl Acidizing Experiments With 3D Simulations

Comparison of Carbonate HCl Acidizing Experiments With 3D Simulations

The First Visualization of Acid Treatments on Carbonates With 3D Nuclear-Magnetic-Resonance Imaging

The First Visualization of Acid Treatments on Carbonates With 3D Nuclear Magnetic Resonance Imaging (NMRI)

Contact Info

Product

Resources

About