The Effects of Acid Contact Time and the Resulting Weakening of the Rock
Surfaces on Acid-Fracture Conductivity

Melendez, Maria; Pournik, Maysam; Zhu, Ding; Hill, A.D.

doi:10.2523/107772-ms

Cited by 20 publications

(12 citation statements)

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“…10: Conductivity Laboratory Setup. From Melendez, 2007 After acidizing, to simulate fluid flow through a created fracture, nitrogen is flowed through a closed system at varying flow rates and the corresponding pressure drop is recorded under different closure stresses. A flowmeter is used to monitor the nitrogen flowing through the system and to vary the flowrates to obtain data.…”

Section: Objectives Of Researchmentioning

confidence: 99%

“…35. Melendez, 2007 When roughness was observed, the higher the rock strength determined from Brinell Hardness Number, the higher the resulting conductivity. Stress is absorbed on the high points, or points of support, created from the roughness pattern which helps even out the stress distribution on the fracture.…”

Section: Roughness Turbulencementioning

confidence: 99%

“…37: Effect of Surface Structure on Conductivity. From Melendez, 2007 If there is no surface etching, there is nothing to help keep the fracture opened.…”

Section: Roughness Turbulencementioning

confidence: 99%

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Acid Fracturing Carbonate-Rich Shale: A Feasibility Investigation of Eagle Ford Formation

Cash

Zhu

Hill

2016

Day 3 Fri, August 26, 2016

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Due to the extensive technically recoverable shale natural gas resources and an increase in production from shale plays over the last 10 years, it is essential to focus on stimulation techniques to enhance productivity in shale resources. One such stimulation technique is acid fracturing. Similar to hydraulic fracturing, acid fracturing injects acid into a formation at a pressure greater than the fracture pressure, creating fractures and etching the created fracture face. The high carbonate content of the Eagle Ford Shale makes the formation a possible acid fracturing candidate. Minimal research has been completed on the effects of acid fracturing high carbonate-containing shale formations, where various conditions can limit the permeability of petroleum fluids. In this study, eight Eagle Ford shale samples, four from Zone C and four from Zone D, are used to determine the effect of surface etching pattern, acid concentration, calcite content, and Brinell Hardness Number on created acid fracture conductivity in the Eagle Ford shale. The resultant surface etching volume is determined by a pre-and post-surface Profilometer scan to calculate the change in surface profile. Calcite content is determined by X-Ray Diffraction analyses. Conductivity tests are performed on the eight samples up to a closure stress of 4000 psi, sample integrity permitting. Based on the results determined in this study, acid fracturing the Eagle Ford shale could provide optimistic increases in production. Acid fracturing treatments in high calcite containing zones of the Eagle Ford shale are expected to result in an increase in productivity. For the Eagle Ford Shale, the surface etching patterns that result in iii highly sustained conductivity values are channeling and roughness. A direct correlation is shown between calcite content of the shale and resultant surface etching volume. Furthermore, the higher the calcite content of the samples, the more likely the etching pattern will result in channeling and surface roughness. Brinell Hardness tests are completed on Eagle Ford samples determining that, on average, the higher the Brinell Hardness number, the better resulting surface etching pattern and sustained acid fracture conductivity.iv

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Section: Objectives Of Researchmentioning

confidence: 99%

Section: Roughness Turbulencementioning

confidence: 99%

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Acid Fracturing Carbonate-Rich Shale: A Feasibility Investigation of Eagle Ford Formation

Cash

Zhu

Hill

2016

Day 3 Fri, August 26, 2016

Self Cite

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“…Detailed discussion of experimental setup can be found in Zou (2006) with more detailed information on rock strength measurements in Melendez (2007) and surface etching characteristics in Malagon (2007). It was designed to accommodate larger rock samples, higher injection rates, and higher temperatures.…”

Section: Acid-fracture Conductivity Experimentsmentioning

confidence: 99%

“…As the effect of treatment conditions on resulting fracture conductivity and fracture face strength (Melendez et al 2007;Pournik et al 2007) and characterization of etched fracture surfaces (Malagon et al 2006;Antelo et al 2009) were discussed before, this study focuses on the effect of rock type and statistical properties on etching pattern and resulting conductivity. Total of 62 experiments were conducted with several different acid systems and rock types at different acid contact times.…”

Section: Introductionmentioning

confidence: 99%

Acid-Fracture Conductivity Correlation Development Based on Acid-Fracture Characterization

2009

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Acid fracturing is a stimulation process in which the dissolution of formation rock leaves unevenly etched fracture faces that creates lasting conductivity after fracture closure. The success of acid fracturing depends on the conductivity created and retained under overburden stress in addition to the length of conductive fracture. In order to have sufficient conductivity after fracture closure, the fracture face must be non-uniformly etched by the acid while the strength of the rock is still maintained at high levels to withstand the closure stress.A systematic experimental study to investigate the effect of etching pattern and rock strength on the resulting fracture conductivity was conducted in a laboratory facility designed to perform acid fracture conductivity characterization. Detailed etched surface characterization and rock strength measurement were performed on acid etched fracture faces in order to correlate to resulting conductivity.Resulting fracture conductivities clearly show the importance of characterizing acid etching patterns. In evaluating the measured fracture conductivities, we distinguished between those tests in which a prominent channel was created along the middle of the rock samples from those tests in which more uniformly distributed roughness features were created on the fracture faces. The channels developed in small scale laboratory tests are likely artifacts of the apparatus and cannot be expected to scale to field conditions. For the roughly etched fracture faces, statistical parameters describing the surface roughness in addition to average fracture width were needed to accurately predict measured conductivities. Both etched pattern characterization and resulting conductivity measurements suggested the need to model conductivity of limestone and dolomite samples separately. New conductivity correlations were developed both for limestone and dolomite formations which matched the experimental results better than previous correlations.

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A Thermal–Hydraulic–Mechanical–Chemical Coupling Model for Acid Fracture Propagation Based on a Phase-Field Method

Dai,

Hou,

Lee

et al. 2024

Rock Mech Rock Eng

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The Effects of Acid Contact Time and the Resulting Weakening of the Rock Surfaces on Acid-Fracture Conductivity

Cited by 20 publications

References 0 publications

Acid Fracturing Carbonate-Rich Shale: A Feasibility Investigation of Eagle Ford Formation

Acid Fracturing Carbonate-Rich Shale: A Feasibility Investigation of Eagle Ford Formation

Acid-Fracture Conductivity Correlation Development Based on Acid-Fracture Characterization

A Thermal–Hydraulic–Mechanical–Chemical Coupling Model for Acid Fracture Propagation Based on a Phase-Field Method

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