A Novel Pore-Scale Thermal-Fracture-Acidizing Model With Heterogeneous Rock Properties

SPE Journal ◽  
2016 ◽  
Vol 21 (01) ◽  
pp. 280-292 ◽  
Author(s):  
John Lyons ◽  
Hadi Nasrabadi ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Mass Transfer ◽  
Reactive Transport ◽  
Reaction Rate ◽  
Oil And Gas ◽  
Injection Rate ◽  
Rock Properties ◽  
Thermal Fracture ◽  
Pore Scale ◽  
Heterogeneous Rock ◽  
Acid Reaction

Summary Fracture acidizing is a well-stimulation technique used to improve the productivity of low-permeability reservoirs and to bypass deep formation damage. The reaction of injected acid with the rock matrix forms etched channels through which oil and gas can then flow upon production. The properties of these etched channels depend on the acid-injection rate, temperature, reaction chemistry, mass-transport properties, and formation mineralogy. As the acid enters the formation, it increases in temperature by heat exchange with the formation and the heat generated by acid reaction with the rock. Thus, the reaction rate, viscosity, and mass transfer of acid inside the fracture also increase. In this study, a new thermal-fracture-acidizing model is presented that uses the lattice Boltzmann method to simulate reactive transport. This method incorporates both accurate hydrodynamics and reaction kinetics at the solid/liquid interface. The temperature update is performed by use of a finite-difference technique. Furthermore, heterogeneity in rock properties (e.g., porosity, permeability, and reaction rate) is included. The result is a model that can accurately simulate realistic fracture geometries and rock properties at the pore scale and that can predict the geometry of the fracture after acidizing. Three thermal-fracture-acidizing simulations are presented here, involving injection of 15 and 28 wt% of hydrochloric acid into a calcite fracture. The results clearly show an increase in the overall fracture dissolution because of the addition of temperature effects (increasing the acid-reaction and mass-transfer rates). It has also been found that by introducing mineral heterogeneity, preferential dissolution leads to the creation of uneven etching across the fracture surfaces, indicating channel formation.

Pore-scale hydrodynamic evolution within carbonate rock during CO2 injection and sequestration

2021 ◽  
Author(s):  
Chi Zhang ◽  
Siyan Liu ◽  
Reza Barati
Keyword(s):  
High Resolution ◽  
Reactive Transport ◽  
Injection Rate ◽  
Mineral Dissolution ◽  
Co2 Injection ◽  
Pore Scale ◽  
Modeling Framework ◽  
Calcite Dissolution ◽  
Potential Factors ◽  
The Impact

<p><span>The continuously rising threat of global warming caused by human activities related to CO</span><span><sub>2</sub> emission is facilitating the development of greenhouse gas control technologies. Subsurface CO</span><span><sub>2</sub> injection and sequestration is one of the promising techniques to store CO</span><span><sub>2</sub> in the subsurface. </span><span> </span><span>However, during CO<sub>2</sub> injection, the mechanisms of processes like injectant immobilizations and trapping and pore-scale geochemical reactions such as mineral dissolution/precipitation are not well understood. Consequently, the multi-physics modeling approach is essential to elucidate the impact of all potential factors during CO<sub>2</sub> injection, thus to facilitate the optimization of this engineered application.</span> </p><p><span>Here, we propose a coupled framework to fully utilize the capabilities of the geochemical reaction solver PHREEQC while preserving the Lattice-Boltzmann Method (LBM) high-resolution pore-scale fluid flow integrated with diffusion processes. The model can simulate the dynamic fluid-solid interactions with equilibrium, kinetics, and surface reactions under the reactive-transport scheme.  In a simplified 2D spherical pack, we focused on examining the impact of pore sizes, grain size distributions, porosity, and permeability on the calcite dissolution/precipitation rate. Our simulation results show that the higher permeability, injection rate, and more local pore connectivity would significantly increase the reaction rate, then accelerate the pore-scale geometrical evolutions. Meanwhile, model accuracy is not sacrificed by reducing the number of reactants/species within the system.</span></p><p><span>Our modeling framework provides high-resolution details of the pore-scale fluid-solid interaction dynamics. To gain more insights into the mineral-fluid interfacial properties during CO</span><span><sub>2</sub> sequestration, our next step is to combine the electrodynamic forces into the model. Potentially, the proposed framework can be used for model upscaling and adaptive subsurface management in the future. </span><span> </span></p>

scholarly journals Geochemical Investigation of CO2 Injection in Oil and Gas Reservoirs of Middle East to Estimate the Formation Damage and Related Oil Recovery

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7676
Author(s):  
Ilyas Khurshid ◽  
Imran Afgan
Keyword(s):  
Oil Recovery ◽  
Oil And Gas ◽  
Injection Rate ◽  
Rock Properties ◽  
Co2 Injection ◽  
Formation Damage ◽  
Gas Reservoirs ◽  
Oil And Gas Reservoirs ◽  
Carbon Dioxide Co2 ◽  
Injection Rates

The injection performance of carbon dioxide (CO2) for oil recovery depends upon its injection capability and the actual injection rate. The CO2–rock–water interaction could cause severe formation damage by plugging the reservoir pores and reducing the permeability of the reservoir. In this study, a simulator was developed to model the reactivity of injected CO2 at various reservoir depths, under different temperature and pressure conditions. Through the estimation of location and magnitude of the chemical reactions, the simulator is able to predict the effects of change in the reservoir porosity, permeability (due to the formation/dissolution) and transport/deposition of dissoluted particles. The paper also presents the effect of asphaltene on the shift of relative permeability curve and the related oil recovery. Finally, the effect of CO2 injection rate is analyzed to demonstrate the effect of CO2 miscibility on oil recovery from a reservoir. The developed model is validated against the experimental data. The predicted results show that the reservoir temperature, its depth, concentration of asphaltene and rock properties have a significant effect on formation/dissolution and precipitation during CO2 injection. Results showed that deep oil and gas reservoirs are good candidates for CO2 sequestration compared to shallow reservoirs, due to increased temperatures that reduce the dissolution rate and lower the solid precipitation. However, asphaltene deposition reduced the oil recovery by 10%. Moreover, the sensitivity analysis of CO2 injection rates was performed to identify the effect of CO2 injection rate on reduced permeability in deep and high-temperature formations. It was found that increased CO2 injection rates and pressures enable us to reach miscibility pressure. Once this pressure is reached, there are less benefits of injecting CO2 at a higher rate for better pressure maintenance and no further diminution of residual oil.

Simulation of proppant transport and fracture plugging in the framework of a radial hydraulic fracturing model

2020 ◽  
Vol 35 (6) ◽  
pp. 325-339
Author(s):  
Vasily N. Lapin ◽  
Denis V. Esipov
Keyword(s):  
Numerical Model ◽  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Injection Rate ◽  
Fluid Injection ◽  
Subtraction Technique ◽  
Gas Industry ◽  
Proppant Transport ◽  
Hydraulic Fracture Propagation

AbstractHydraulic fracturing technology is widely used in the oil and gas industry. A part of the technology consists in injecting a mixture of proppant and fluid into the fracture. Proppant significantly increases the viscosity of the injected mixture and can cause plugging of the fracture. In this paper we propose a numerical model of hydraulic fracture propagation within the framework of the radial geometry taking into account the proppant transport and possible plugging. The finite difference method and the singularity subtraction technique near the fracture tip are used in the numerical model. Based on the simulation results it was found that depending on the parameters of the rock, fluid, and fluid injection rate, the plugging can be caused by two reasons. A parameter was introduced to separate these two cases. If this parameter is large enough, then the plugging occurs due to reaching the maximum possible concentration of proppant far from the fracture tip. If its value is small, then the plugging is caused by the proppant reaching a narrow part of the fracture near its tip. The numerical experiments give an estimate of the radius of the filled with proppant part of the fracture for various injection rates and leakages into the rock.

scholarly journals Linear Exchange Model for the Description of Mass Transfer Limited Bioavailability at the Pore Scale

2010 ◽  
Vol 44 (6) ◽  
pp. 2064-2071 ◽  
Author(s):  
Falk Hesse ◽  
Hauke Harms ◽  
Sabine Attinger ◽  
Martin Thullner
Keyword(s):  
Mass Transfer ◽  
Exchange Model ◽  
Pore Scale ◽  
Linear Exchange ◽  
Linear Exchange Model

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

2015 ◽  
Vol 782 ◽  
pp. 260-299 ◽  
Author(s):  
Preyas N. Shah ◽  
Eric S. G. Shaqfeh
Keyword(s):  
Mass Transfer ◽  
Shear Rate ◽  
Shear Flow ◽  
Reaction Rate ◽  
Patch Size ◽  
Patch Area ◽  
First Order ◽  
Effective Boundary ◽  
Order Surface ◽  
Slip Distance

Surfaces that include heterogeneous mass transfer at the microscale are ubiquitous in nature and engineering. Many such media are modelled via an effective surface reaction rate or mass transfer coefficient employing the conventional ansatz of kinetically limited transport at the microscale. However, this assumption is not always valid, particularly when there is strong flow. We are interested in modelling reactive and/or porous surfaces that occur in systems where the effective Damköhler number at the microscale can be $O(1)$ and the local Péclet number may be large. In order to expand the range of the effective mass transfer surface coefficient, we study transport from a uniform bath of species in an unbounded shear flow over a flat surface. This surface has a heterogeneous distribution of first-order surface-reactive circular patches (or pores). To understand the physics at the length scale of the patch size, we first analyse the flux to a single reactive patch. We use both analytic and boundary element simulations for this purpose. The shear flow induces a 3-D concentration wake structure downstream of the patch. When two patches are aligned in the shear direction, the wakes interact to reduce the per patch flux compared with the single-patch case. Having determined the length scale of the interaction between two patches, we study the transport to a periodic and disordered distribution of patches again using analytic and boundary integral techniques. We obtain, up to non-dilute patch area fraction, an effective boundary condition for the transport to the patches that depends on the local mass transfer coefficient (or reaction rate) and shear rate. We demonstrate that this boundary condition replaces the details of the heterogeneous surfaces at a wall-normal effective slip distance also determined for non-dilute patch area fractions. The slip distance again depends on the shear rate, and weakly on the reaction rate, and scales with the patch size. These effective boundary conditions can be used directly in large-scale physics simulations as long as the local shear rate, reaction rate and patch area fraction are known.

Pore-scale investigation on multiphase reactive transport for the conversion of levulinic acid to γ-valerolactone with Ru/C catalyst

2021 ◽  
pp. 130917
Author(s):  
Xiangqian Wei ◽  
Wenzhi Li ◽  
Qiying Liu ◽  
Weitao Sun ◽  
Siwei Liu ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Levulinic Acid ◽  
Pore Scale

Comparison of Wormhole Profiles on Carbonate Rocks Using Emulsified and Single-Phase Retarded Acids

2022 ◽  
Author(s):  
Norah Aljuryyed ◽  
Abdullah Al Moajil ◽  
Sinan Caliskan ◽  
Saeed Alghamdi
Keyword(s):  
Organic Acids ◽  
Single Phase ◽  
Injection Rate ◽  
Flow Rates ◽  
Low Viscosity ◽  
Propagation Behavior ◽  
Additional Equipment ◽  
Acid Reaction ◽  
Optimum Injection Rate ◽  
Indiana Limestone

Abstract Acid retardation through emulsification is commonly used in reservoir stimulation operations, however, emulsified acid are viscous fluids, thus require additional equipment at field for preparation and pumping requirements. Mixture of HCl with organic acids and/or chemical retarders have been used developed to retard acid reaction with carbonate, however, lower dissolving power. Development of low viscosity and high dissolving retarded acid recipes (e.g., equivalent to 15-26 wt.% HCl) addresses the drawbacks of emulsified acids and HCl acid mixtures with weaker organic acids. The objective of this study is to compare wormhole profile generated as a result of injecting acids in Indian limestone cores using 28 wt.% emulsified acid and single-phase retarded acids at comparable dissolving power at 200 and 300°F. Coreflood analysis testing was conducted using Indiana limestone core plugs to assess the pore volume profile of retarded acid at temperatures of 200 and 300° F. This test is supported by Computed Tomography to evaluate the propagation behavior as a result of the fluid/rock reaction. Wider wormholes were observed with 28 wt.% emulsified acid at 200°F when compared to test results conducted at 300°F. The optimum injection rate was 1 cm3/min at 200 and 300°F based on wormhole profile and examined flow rates. Generally, face-dissolution and wider wormholes were observed with emulsified acids, especially at 200°F. Narrower wormholes were formed as a result of injecting retarded acids into Indiana limestone cores compared to 28 wt.% emulsified acid. Breakthrough was not achieved with retarded acid recipe at 300°F and flow rates of 1 and 3 cm3/min, suggesting higher flow rates (e.g., > 3 cm3/min) are required for the retarded acid to be more effective at 300°F.

Boosting Algorithm Choice in Predictive Machine Learning Models for Fracturing Applications

2021 ◽  
Author(s):  
Abdul Muqtadir Khan
Keyword(s):  
Machine Learning ◽  
Data Science ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Injection Rate ◽  
Model Construction ◽  
Gradient Boosting ◽  
Light Gradient ◽  
Fracture Damage ◽  
Boosting Technique

Abstract With the advancement in machine learning (ML) applications, some recent research has been conducted to optimize fracturing treatments. There are a variety of models available using various objective functions for optimization and different mathematical techniques. There is a need to extend the ML techniques to optimize the choice of algorithm. For fracturing treatment design, the literature for comparative algorithm performance is sparse. The research predominantly shows that compared to the most commonly used regressors and classifiers, some sort of boosting technique consistently outperforms on model testing and prediction accuracy. A database was constructed for a heterogeneous reservoir. Four widely used boosting algorithms were used on the database to predict the design only from the output of a short injection/falloff test. Feature importance analysis was done on eight output parameters from the falloff analysis, and six were finalized for the model construction. The outputs selected for prediction were fracturing fluid efficiency, proppant mass, maximum proppant concentration, and injection rate. Extreme gradient boost (XGBoost), categorical boost (CatBoost), adaptive boost (AdaBoost), and light gradient boosting machine (LGBM) were the algorithms finalized for the comparative study. The sensitivity was done for a different number of classes (four, five, and six) to establish a balance between accuracy and prediction granularity. The results showed that the best algorithm choice was between XGBoost and CatBoost for the predicted parameters under certain model construction conditions. The accuracy for all outputs for the holdout sets varied between 80 and 92%, showing robust significance for a wider utilization of these models. Data science has contributed to various oil and gas industry domains and has tremendous applications in the stimulation domain. The research and review conducted in this paper add a valuable resource for the user to build digital databases and use the appropriate algorithm without much trial and error. Implementing this model reduced the complexity of the proppant fracturing treatment redesign process, enhanced operational efficiency, and reduced fracture damage by eliminating minifrac steps with crosslinked gel.

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