Chelating Agents as Acid-Fracturing Fluids: Experimental and Modeling Studies

Tariq, Zeeshan; Aljawad, Murtada Saleh; Hassan, Amjed; Mahmoud, Mohamed; Al‐Ramadhan, Ammar

doi:10.1021/acs.energyfuels.0c04045

Cited by 24 publications

(13 citation statements)

References 56 publications

(93 reference statements)

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“…On the other hand, others investigated the effect of acid treatment on the mechanical rock structure (Zhang et al 2020b) and the influence of the rock mineralogy on acidizing efficiency (Martyushev et al 2022). Various acidizing fluids such as self-diverting acid (Bazin et al 1999;Lungwitz et al 2007), visco-elastic surfactant (VES) acid, gelled acid, self-generated acids, and recently, emulsified acid (Martyushev and Vinogradov 2021) and chelating agents (Tariq et al 2021) have been developed and investigated both in the laboratory and in field-scale (Gou et al 2021;Hassan and Al-Hashim 2017;Isah et al 2021a, b;Kiani et al 2021;Lai et al 2021;Li and Shi 2021;Martyushev and Vinogradov 2021;Melendez et al 2007;Taylor and Nasr-El-Din 2001).…”

Section: Introductionmentioning

confidence: 99%

Effect of acid treatment on the geomechanical properties of rocks: an experimental investigation in Ahdeb oil field

Alameedy

Alhaleem

Isah

et al. 2022

J Petrol Explor Prod Technol

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Acidizing is one of the most used stimulation techniques in the petroleum industry. Several reports have been issued on the difficulties encountered during the stimulation operation of the Ahdeb oil field, particularly in the development of the Mishrif reservoir, including the following: (1) high injection pressures make it difficult to inject acid into the reservoir formation, and (2) only a few acid jobs have been effective in Ahdeb oil wells, while the bulk of the others has been unsuccessful. The significant failure rate of oil well stimulation in this deposit necessitates more investigations. Thus, we carried out this experimental study to systematically investigate the influence of acid treatment on the geomechanical properties of Mi4 formation of the Mishrif reservoir. The acid core-flood experiments were performed on seven core samples from the oil reservoir in central Iraq. The porosity, permeability, acoustic velocities, rock strength, and dynamic elastic parameters were computed before and after the acidizing treatment. To determine the optimal acid injection rate, different injection flow rates were used in the core-flooding experiments. The propagation of an acid-induced wormhole and its effect on the rock properties were analyzed and compared to that of intact rocks. Computed tomography (CT) scan and a 3D reconstruction technique were also conducted to establish the size and geometry of the generated wormhole. To analyze the influence of mineralogical variation and heterogeneity and confirm the consistency of the outcomes, acidizing experiments on different rock samples were conducted. The results demonstrate that for all the rock samples studied, the mechanical properties exhibit rock weakening post-acid treatment. The Young’s modulus reduced by 26% to 37%, while the Poisson’s ratio, the coefficient of lateral earth pressure at rest, and the material index increased by 13% to 20%, 23% to 32%, and 28% to 125%, respectively. The CT scan visually confirmed that the acid treatment effectively creates a pathway for fluid flow through the core.

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Section: Introductionmentioning

confidence: 99%

Effect of acid treatment on the geomechanical properties of rocks: an experimental investigation in Ahdeb oil field

Alameedy

Alhaleem

Isah

et al. 2022

J Petrol Explor Prod Technol

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“…Through core-flooding experiments, Barri et al [ 51 ] found that DTPA can create wormholes in the carbonate reservoir rocks. Recently in our previous study [ 52 ], we found that chelating agents can improve the fracture conductivity by many folds because of the rock dissolution. Based on previous experiences, DTPA and GLDA were used to dissolve filter cake.…”

Section: Methodsmentioning

confidence: 99%

Reduction of Breakdown Pressure by Filter Cake Removal Using Thermochemical Fluids and Solvents: Experimental and Numerical Studies

et al. 2021

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The process of well cleanup involves the removal of an impermeable layer of filter cake from the face of the formation. The inefficient removal of the filter cake imposes difficulty on fracturing operations. Filter cake’s impermeable features increase the required pressure to fracture the formation. In this study, a novel method is introduced to reduce the required breakdown pressure to fracture the formation containing the water-based drilling fluid filter cake. The breakdown pressure was tested for five samples of similar properties using different solutions. A simulated borehole was drilled in the core samples. An impermeable filter cake using barite-weighted drilling fluid was built on the face of the drilled hole of each sample. The breakdown pressure for the virgin sample without damage (filter cake) was 6.9 MPa. The breakdown pressure increased to 26.7 MPa after the formation of an impermeable filter cake. Partial removal of filter cake by chelating agent reduced the breakdown pressure to 17.9 MPa. Complete dissolution of the filter cake with chelating agents resulted in the breakdown pressure approximately equivalent to the virgin rock breakdown pressure, i.e., 6.8 MPa. The combined thermochemical and chelating agent solution removed the filter cake and reduced the breakdown pressure to 3.8 MPa. Post-treatment analysis was carried out using nuclear magnetic resonance (NMR) and scratch test. NMR showed the pore size redistributions with good communication between different pores after the thermochemical removal of filter cake. At the same time, there was no communication between the different pores due to permeability impairment after filter cake formation. The diffusion coupling through NMR scans confirmed the higher interconnectivity between different pores systems after the combined thermochemical and chelating agent treatment. Compressive strength was measured from the scratch test, confirming that filter cake formation caused added strength to the rock that impacts the rock breakdown pressure. The average compressive strength of the original specimen was 44.5 MPa that increased to 73.5 MPa after the formation of filter cake. When the filter cake was partially removed, the strength was reduced to 61.7 MPa. Complete removal with chelating agents removed the extra strength that was added due to the filter cake presence. Thermochemical and chelating agents resulted in a significantly lower compressive strength of 25.3 MPa. A numerical model was created to observe the reduction in breakdown pressure due to the thermochemical treatment of the filter cake. The result presented in this study showed the engineering applications of thermochemical treatment for filter cake removal.

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“…Several experiments/measurements were performed, the lab-scale outcomes were reproduced numerically, and field-scale simulations were carried out. 30 …”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing

Guo

Liu

et al. 2022

ACS Omega

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As an important part of the acid fracturing process of carbonate reservoir, the performance of acid fracturing working fluid directly affects the stimulation effect of oil wells. In this paper, formaldehyde (agent A) and ammonium chloride (agent B) were used as the matrix. Several aldehydes with different volume ratios were prepared. The acid ratio with the highest acid yield was selected by the sodium hydroxide titration experiment. The results show that when the volume ratio of agent A to agent B is 1:1.3, the acid production capacity is the strongest. The pH values at several time points in the process of acid reaction were measured by a pen pH meter. The relationship curve between acid production capacity and time was obtained. The acid production capacity increased with time. It tends to be stable after a certain time. The experiment of acid rock reaction kinetics shows that the reaction rate between acid and rock decreases with the extension of time. The reaction time can reach 6 h. The reaction rate of autogenic acid under different temperatures and concentrations ranges from 6.61 × 10 –7 to 9.49 × 10 –7 mol/(s·cm 2 ) within 6 h. Therefore, it indicates that the reaction time between autogenic acid and carbonate rock is long and the reaction rate is low. It is beneficial to improve the acid treatment effect of the carbonate reservoir. The conductivity experiments show that at different temperatures, with the increase of sealing pressure, the etching ability of autogenic acid decreases. The etching effect is better at 338 K. After etching, the permeability and conductivity of the rock slab of 5 MPa closure pressure are 227 D and 72.62 D·cm, respectively. To sum up, this autogenic acid is an effective working fluid in the acid fracturing process of the carbonate reservoir. It can obviously reduce the reaction rate of acid rock and has certain conductivity.

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Chelating Agents as Acid-Fracturing Fluids: Experimental and Modeling Studies

Cited by 24 publications

References 56 publications

Effect of acid treatment on the geomechanical properties of rocks: an experimental investigation in Ahdeb oil field

Effect of acid treatment on the geomechanical properties of rocks: an experimental investigation in Ahdeb oil field

Reduction of Breakdown Pressure by Filter Cake Removal Using Thermochemical Fluids and Solvents: Experimental and Numerical Studies

Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing

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