Application status and research progress of shale reservoirs acid treatment technology

Li, Nianyin; Dai, Jinxin; Jian-hui, LI; Bai, Fengjun; Liu, Pingli; Luo, Zhifeng

doi:10.1016/j.ngib.2016.06.001

Cited by 18 publications

(8 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During stimulation, water-based hydraulic fracturing fluids (HFFs) are pumped down the wellbore at elevated pressures to promote cracking and enhance permeability of the shale reservoir. This injection process follows a pumping schedule with multiple stages (Frackoptima, 2014(Frackoptima, , 2017Crawley, 2016;Li et al, 2016;Oilfieldbasics, 2019;Khan et al, 2021;Jew et al, 2022). First, a concentrated acid spearhead is injected to partly dissolve minerals and aid in fracture initiation.…”

Section: Introductionmentioning

confidence: 99%

“…Breakers are also introduced, which decompose viscous gels at a delayed time, lowering the viscosity of the fluid before flowing back. Although varying greatly across operators, each of the pumping stages typically lasts for minutes, and the total pumping project is more than an hour (Eberhard, 2011;Frackoptima, 2014;Li et al, 2016;Oilfieldbasics, 2019). After the injection stops, a shut-in stage of several weeks to months begins, allowing fractures to close on the proppant, after which production can last for years (Frackoptima, 2014;Crawley, 2016;Oilfieldbasics, 2019;Wang et al, 2020;Khan et al, 2021;Jew et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of sequential stimulation practices on geochemical alteration of shale

Druhan²,

Bargar³

2022

Front. Water

View full text Add to dashboard Cite

Water-based hydraulic fracturing fluids (HFFs) can chemically interact with formation shale, resulting in altered porosity and permeability of the host rock. Experimental investigations of spatial and temporal shale-HFF interactions are helpful in interpreting chemical compositions of the injectate, as well as predicting alteration of hydraulic properties in the reservoir due to mineral dissolution and precipitation. Most bench-top experiments designed to study shale-HFF chemical interactions, either using batch reactors or flow-through setups, are carried out assuming that the acid spearhead has already become mixed with neutral HFFs. During operations, however, HFFs are typically injected according to a sequenced pumping schedule, starting with a concentrated acid spearhead, followed by multiple additions of near-neutral pH HFFs containing chemical amendments and proppant. In this study, we use geochemical modeling to consider whether this pre-mixed experimental protocol provides results directly comparable to a sequential discrete fluid-shale interaction protocol. Our results show that for the batch system, the transient evolution in major ion concentrations is faster with the sequential procedure. After 2 h of reaction time, the two protocols converge to the same aqueous concentrations. In a flow-through geometry, the pre-mixed model predicts extensive chemical alteration close to the injection point but negligible alteration downstream. In contrast, the sequential model predicts mineral reactions over hundreds of meters along the flow path. The extent of shale alteration in the sequential model at a given location depends on shale mineralogy and where the acid spearhead resides during the shut-in period. The predictive model developed in this study can help experimentalists to design bench-top tests and operators to better translate the results of laboratory experiments into practical applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of sequential stimulation practices on geochemical alteration of shale

Druhan²,

Bargar³

2022

Front. Water

View full text Add to dashboard Cite

show abstract

“…Random and complex morphology is one inherent feature of underground fractures, especially the surface roughness is increased due to acid corrosion or treatment when the calcite-enrichment area is dissolved in priority (Li et al, 2016;Ogilvie et al, 2006;Yang et al, 2018). Because of the fluctuation characteristics of fracture surface accord with normal distribution, the Gauss Model has been widely accepted for constructing surface profiles that more tally with the actual situation (Guo et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Numerical study on particle transport and deposition in rough fractures

Wang

Gong

et al. 2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

View full text Add to dashboard Cite

The transport and deposition of particulate materials through fractures is widely involved in environmental engineering and resource development engineering. A 3D Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupling method was used to investigate the particle and fluid flow. The Gauss Model was applied to construct the rough surfaces. First, the numerical results were compared with the previous results and reasonable agreements were obtained. Second, the results indicated a novel flow pattern of particles in rough fractures. Then, a comprehensive particle sedimentary analysis indicated that the deposition distance of particles was inversely proportional to the particle size and density ratio. In addition, the particle deposition rates were increased by the mean roughness and there was an uneven sediment distribution impacted by roughness. Reasons for this uneven sediment distribution were analyzed in detail. Moreover, the bridge plugs of particles considering the closure of fractures were simulated as well. A part of particulate materials would be filtered at the inlet due to size effect and the transport distance of entered particles decreased significantly when the particle was large. A critical particle radius (R < 0.27 mm) that can flow through closure fracture in this work was found. This work can provide a clear insight into the migration and deposition characteristics of particles in the rough fractures underground.

show abstract

“…6,7 Although the concept of acid HF is relatively new, other acid treatment technologies such as downhole acidic scale removal and matrix acidizing are well-established and have been widely implemented. 8 The concept of matrix acidizing even dates back to 1895 where concentrated HCl acid was used to stimulate the matrix of carbonate reservoirs. 9 One of the technical challenges associated with the implementation of acid treatment in either carbonate reservoirs or carbonate-rich shale reservoirs is the high reactivity of the acidizing fluids.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The conductivity of these fractures (without any proppants) is retained by the nonuniform etching/roughness even after fracture closure. Several studies have recommended the combination of proppant HF and acid HF for effective reservoir stimulation. , Although the concept of acid HF is relatively new, other acid treatment technologies such as downhole acidic scale removal and matrix acidizing are well-established and have been widely implemented . The concept of matrix acidizing even dates back to 1895 where concentrated HCl acid was used to stimulate the matrix of carbonate reservoirs…”

Section: Introductionmentioning

confidence: 99%

Microencapsulation of Acids by Nanoparticles for Acid Treatment of Shales

2017

View full text Add to dashboard Cite

Acid treatment is one of the common well-stimulation techniques to improve the production in tight carbonates or calcite-rich shale reservoirs. Because the reaction rates are often too large at the reservoir temperatures, retarded acid systems such as emulsified acids, foamed acids, and polymer-gelled acids are used. The retarded acids also minimize damage to the wellbore and propagate acids long-distance from the wellbore in fractured shales. In this work, a novel encapsulation method of highly concentrated acid (∼10 wt % HCl) is reported as an alternative retarded acid system. Microencapsulation of these acids is performed using highly hydrophobic silica nanoparticles. The mixing of these particles with acid under high shear rates results in the formation of acid-in-air powders. The release of acid from these powders could be triggered by external stimuli such as mechanical pressure or surfactant addition. The thermal stability, corrosion inhibition efficiency, and shale surface reactivity are compared to conventional acid-in-oil emulsions, which are typically used for shale acidization processes. The encapsulation is found to be quite robust at 80 °C, and half-life (time taken to release 50% of encapsulated acid) is increased by more than 2 orders of magnitude as compared to acid-in-oil emulsions. A gravimetric measurement technique is used to quantify the iron corrosion rate for these two systems. The corrosion rate for the case of powders is found to be lower than that of emulsions at all of the studied temperatures (25, 60, and 80 °C). The shale surface topography is analyzed using an optical profilometer before and after the surface treatment with these two encapsulated-acid systems. The release of acid from powders, triggered via mechanical pressure, results in surface etching, which could potentially increase the fracture conductivity in shales. The release of acid can also be enhanced by the addition of anionic surfactants in the carrier fluid. The simplicity of the acid-in-powder generation process along with excellent thermal stability and corrosion inhibition efficiency makes the proposed acidencapsulation technique lucrative for acid treatment applications.

show abstract

Application status and research progress of shale reservoirs acid treatment technology

Cited by 18 publications

References 35 publications

Influence of sequential stimulation practices on geochemical alteration of shale

Influence of sequential stimulation practices on geochemical alteration of shale

Numerical study on particle transport and deposition in rough fractures

Microencapsulation of Acids by Nanoparticles for Acid Treatment of Shales

Contact Info

Product

Resources

About