Rock Permeability Research Articles

Advances in enhanced geothermal systems: Integrating laboratory, numerical and field insights

An enhanced geothermal system is a designed and engineered thermal reservoir that has been deliberately stimulated to extract economically viable amounts of heat from geothermal resources having no natural permeability. Enhanced geothermal system projects are typically initiated to meet the industrial production standards, usually via techniques such as chemical stimulation, hydraulic fracturing, or thermal processes to enhance the permeability of the reservoir. The main aim of this study is to evaluate the current advancements in enhanced geothermal system through a comprehensive examination of laboratory experiments, numerical simulation, and fieldwork investigations from numerous studies that are insufficient captures and combined by current open literature. This study highlighted the critical importance of precisely developing fracture systems, whether natural or artificially induced, in ensuring the effectiveness of such projects. Notably, hydraulic fracturing techniques have been proven instrumental in enhancing the performance of enhanced geothermal systems. On the contrary, research conducted through numerical simulations has demonstrated consistent findings that it is beneficial to enhance the permeability of low-permeability rock for the efficient use of enhanced geothermal systems. Additionally, this study has highlighted the intricate and expensive nature of designing enhanced geothermal systems due to uncertainties in subsurface conditions especially from projects that are in initial stages of development. This study enables researchers and operators to improve the efficiency and safety of geothermal energy extraction, paving the way for more sustainable enhanced geothermal system projects in the future.

Precipitants transport during post-flush and its impacts

Wellbore stimulation is often needed for different situations in the field ranging from deepwater frac-packs to enhanced geothermal systems. Acidizing is commonly designed for cleaning perforation, recovering perforation functions, and improving injectivity during completion operations such as frac-pack, aiming to reduce the fracturing pressure and enhance productivity. However, some field observations have shown unexpected breakdown pressure increases after the post-flush period of acid treatment in sandstone reservoirs. To understand this problem, a 3D model has been established in this paper to simulate the acidizing process through a perforation hole, and then the subsequent post-flush resulting in precipitant transport. Finally, the breakdown process where fluid is injected into the rock is modeled to compare breakdown pressures in different cases. Our numerical results reveal that although minerals can be effectively dissolved by chemical reactions during the main flush period, the generated precipitants transported during the post-flush period may affect the rock breakdown process. The precipitant transport might develop high-porosity channels, potentially leading to the breakthrough along the precipitant deposits and establishing a string hydraulic communication between the perforation hole and the surrounding rock. The existence of these high-porosity channels enables fluids to flow swiftly into the surroundings, impeding enough pressure accumulation to crack the rock. The formation of high-porosity channels in the post-flush period and its potential impact on the breakdown pressure is influenced by several factors such as post-flush fluid injection rate, acid concentration and viscosity, and the initial rock permeability.

The influence of mining stress paths on rock damage and permeability

The influence of mining stress paths on rock damage and permeability

Microbial Mineralization-Based Rapid and High-Strength Simultaneous Repair of Surrounding Rock Fracture Zones and Lining Cracks

Grouting technology based on microbial mineralization represents a novel approach to enhancing the properties of rock and soil. Widely studied for its combination of high efficiency and environmental friendliness, this method improves the strength and permeability of rock and soil. In this study, a novel approach involving bioslurry + filling particles was proposed to reinforce sand columns. It was observed that the addition of filling particles provided new nucleation sites for crystallization, significantly enhancing the cementation effect of sand particles. After 3 days of grouting treatment, sand columns containing 10% filling particles exhibited an order of magnitude reduction in permeability with the unconfined compressive strength (UCS) reaching 2.5 MPa, more than twice that of sand columns reinforced with bioslurry alone. Additionally, this study presented a method for the simultaneous repair of sand particles and concrete cracks. Results indicated that after 3 days of the grouting treatment, the interfacial shear strength between sand columns and concrete reached 100 kPa. Moreover, for concrete with crack apertures less than 1 mm, the permeability coefficient was reduced by over 80%, while the recovery ratio of the splitting tensile strength reached 64.2%. These findings highlight the potential of microbial mineralized grouting technology in addressing practical challenges, providing a foundation for the rapid and high-strength simultaneous repair of tunnel-surrounding rock fracture zones and lining cracks.

Investigation of pore structure evolution and damage characteristics of high temperature rocks subjected to liquid nitrogen cooling shock

Liquid nitrogen (LN2) can be utilized in the development of enhanced geothermal systems, as well as for deep/ultra-deep hydrocarbon reservoir stimulation, fire suppression, and other high-temperature geological projects. It is a crucial issue in the utilization of LN2 to investigate the pore structure evolution, permeability, and damage characteristics of high-temperature rocks under the influence of LN2 cooling shock. These rocks were first slowly heated to 150∼600°C and held for 2 h, followed by LN2 or natural cooling. The evolution of pore volume in high-temperature rocks affected by liquid nitrogen cooling was quantified. T2 cutoff values were determined through centrifugal tests, while the contents of irreducible and mobile fluids were estimated. Based on the aforementioned analysis as well as changes in irreducible fluid saturation, pore throat, tortuosity, and permeability, this study examines the closure and development of pores along with permeability behavior. The findings suggest that, despite a more pronounced decrease in porosity at lower heating temperatures, LN2 cooling specimens exhibit superior pore connectivity and permeability compared to those cooled naturally. LN2 stimulation not only induces crack initiation and propagation but also results in further cooling induced densification based on heating densification. 225°C is considered to be the optimal temperature for cooling contraction induced densification in this study. At higher heating temperatures, the damage to rock cooled with LN2 is more severe than that of naturally cooled. This results in a greater increase in porosity, movable fluid content and proportion, and permeability of LN2 cooled specimens compared to naturally cooled specimens. The damage mechanism can be better understood by the constructed damage model that coordinates the pore increase/decrease and mutual pore transformation from the perspective of pore evolution.

Acoustic vibration restoration of rock permeability while crude oil filtration containing paraffins

The paper presents the results of experimental studies on the filtration of a reservoir fluid (crude oil containing paraffins) through sedimentary rocks under the influence of acoustic vibrations in an ultrasound band. A laboratory rig is assembled that allows for modeling the filtration of a fluid from a reservoir into a well during the propagation of elastic waves from a well. Medium permeability sandstones are the focus of the study. The effect of acoustic vibrations manifests itself in unblocking the pore space and leads to restoration of rock permeability to different extents. Dependences of rock permeability on the frequency of acoustic vibrations are obtained. A model of the influence of acoustic vibrations on paraffin particles is developed.

Gas Fracturing Simulation of Shale-Gas Reservoirs Considering Damage Effects and Fluid–Solid Coupling

With the increasing demand for energy and the depletion of traditional resources, the development of alternative energy sources has become a critical issue. Shale gas, as an abundant and widely distributed resource, has great potential as a substitute for conventional natural gas. However, due to the low permeability of shale-gas reservoirs, efficient extraction poses significant challenges. The application of hydraulic fracturing technology has been proven to effectively enhance rock permeability, but the influence of environmental factors on its efficiency remains unclear. In this study, we investigate the impact of gas fracturing on shale-gas extraction efficiency under varying environmental conditions using numerical simulations. Our simulations provide a comprehensive analysis of the physical changes that occur during the fracturing process, allowing us to evaluate the effects of gas fracturing on rock mechanics and permeability. We find that gas fracturing can effectively induce internal fractures within the rock, and the magnitude of tensile stress decreases gradually during the process. The boundary pressure of the rock mass is an important factor affecting the effectiveness of gas fracturing, as it exhibits an inverse relationship with the gas content present within the rock specimen. Furthermore, the VL constant demonstrates a direct correlation with gas content, while the permeability and PL constant exhibit an inverse relationship with it. Our simulation results provide insights into the optimization of gas fracturing technology under different geological parameter conditions, offering significant guidance for its practical applications.

Integrated assessment of deep geothermal heating investments in Northern Belgium through techno-economic, life cycle, global sensitivity and real options analysis

The decarbonization of the heating sector is crucial for the green transition of the energy mix. This study investigates threefold the economic and environmental performance of deep geothermal heating investments in Northern Belgium First, techno-economic and life cycle assessment (LCA) are performed, followed by a global sensitivity analysis focusing on the geological uncertainty. Lastly, real options analysis (ROA) is employed to investigate the economic and environmental value of the investors’ flexibility. A novel ROA method is proposed that considers the LCA results to calculate development decisions that minimize the expected environmental impact of the investment. The results show that the economic and environmental performance of the investment vary with the energy prices and the electricity mix. The performance of the investment is driven by the plant’s pumping requirements, which are induced by the relatively low rock permeability at the targeted location. Also, the results’ variability mainly originates by uncertainty regarding the permeability value. Nevertheless, the investors’ flexibility adds large economic and environmental value to the investment. However, the development strategies that optimize the economic or the environmental performance of the plant present some trade-offs. This study demonstrates that the economic and environmental performance of deep geothermal heating investments in Northern Belgium can be improved by focusing on the factors that simultaneously drive the costs, environmental impacts, and their variability. It also shows that utilizing the investors’ flexibility to optimize the investment’s economic and environmental performance can add significant value to the investment.

Numerical modeling of the mineralizing processes within the Shaxi porphyry-type Cu-Au deposit, Eastern China: Influence and restriction from physical and chemical characteristics of host rocks

The Shaxi porphyry-type Cu-Au deposit is located in the northwestern outer margin of the Luzong volcanic basin, which is situated in the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB), Eastern China. It is a large porphyry-type Cu-Au deposit with confirmed copper resources exceeding 1 Mt and gold resources exceeding 40 tons. Previous studies have extensively investigated the genesis, controlling structures, geochemical characteristics, fluid evolution, alteration zone, and ages of mineralization and host rocks in this deposit. However, research on the influence of the physical and chemical properties of the host rocks on the mineralizing processes has not been explored in detail. This study employs the finite element method to apply numerical modeling of multiple physical and chemical fields, interlinking heat transfer, fluid flow, material migration, mineralization reaction, and their coupling with porosity and permeability of rock, to investigation of the influence of different porosities, permeabilities, and chemical properties of the host rocks on the mineralizing processes in the Shaxi deposit. The results show that the porosity and permeability of the host rocks play a significant role in the mineralization of porphyry-type systems. The different porosity and permeability of the intrusions and strata control the depth, the mineralization intensity, the morphology of the ore bodies, and the spatial location of the mineralization center. The chemical properties of the strata significantly restrict the mineralization intensity and horizontal spatial rather than affecting the depth of mineralization. Furthermore, the formation of skarn-type deposits may require a longer period of time than that of porphyry-type deposits under the same mineralization conditions and ore grade. This paper also indicates that the numerical modeling method employed in this study can be used to predict the mineralization depth and spatial location of deep concealed porphyry-type deposits, aiding research in deep-seated mineral exploration.

Investigating the CO2 injection and the performance of nanoparticles in preventing formation damage at different pressures and concentrations

AbstractAsphaltene deposition is one of the main challenges during CO2 injection (miscible or immiscible) into reservoirs. Asphaltene deposition reduces the porosity and permeability of reservoir rock and changes its wettability to strongly oil‐wet. In this article, to control the asphaltene deposition during CO2 injection the use of direct asphaltene inhibitors (Al2O3 and Fe3O4) in reservoir conditions. In this research, nanoparticle screening (to investigate its significance in reducing asphaltene precipitation) has been done and it can be stated that Al2O3 nanoparticle will perform better effectivity than Fe3O4 nanoparticle. After that, by using effective nanoparticles (Al2O3) in different concentrations (1000 and 2000 ppm), the amount of asphaltene deposition during CO2 injection has been investigated. The obtained results show that increasing the injection pressure (from immiscible to miscible) causes an increase in asphaltene deposition and the use of nanoparticles will reduce the amount of asphaltene deposition.

EFFECT OF GRAPHENE OXIDE AQUEOUS DISPERSIONS ON ROCK WETTABILITY

Among the various methods to improve oil recovery from reservoirs (wells stimulation), the use of nanofluids has emerged as a promising alternative for modifying the wettability and permeability of sandstone rocks. For this reason, in this study, graphene oxide (GO) was synthesized from graphite, and a nanofluid was formulated using GO dispersed in water to evaluate its capacity for modifying wettability on sandstone core plugs from Colombian reservoirs. The experimental setup included three preliminary tests: visual wettability, contact angle measurements, and detergency. The results demonstrated an increase in the water wettability of the rocks, leading to a decrease in the contact angle of the water-rock system by up to 42.6%. Additionally, the visual wettability and detergency tests yielded positive results, indicating that graphene oxide is an effective wettability modifier, rendering the rock more water-wet.

Deterioration of volcanic tuffs from rock dwellings in Brhlovce (Slovakia) induced by freeze-thaw cycling studied by non-destructive tests and µCT visualization

The aim of this paper is to evaluate the effect of freeze-thaw-induced weathering of volcanic tuffs from the rock dwellings in the village of Brhlovce (Slovakia) based on a non-destructive and experimental study of tuff pore space properties. Traditional techniques for characterization of the porosity and pore size distribution and new experimental techniques like spontaneous imbibition (pore interconnection) or indicative rock pore structure method (pore size distribution) were compared with pore network models acquired by X-ray computed microtomography before and after freeze-thaw cycling in a custom-built thermodilatometer VLAP04. The results offer insight into how frost weathering altered the pore network of volcanic tuffs. Brhlovce tuffs are highly susceptible to frost damage due to their high porosity, pore interconnectivity, and bimodal pore size distribution pattern, where nanometric-sized micropores predominate over larger micrometric-sized capillary pores. Poromechanical principles were applied to confirm that ice crystallization initiates in well-connected micropores with a corresponding crystallization pressure below 10 MPa. After undergoing 100 freeze-thaw cycles with temperature oscillations ranging from − 10 to 10 °C, there was a significant increase in total porosity, pore interconnectivity, and rock permeability. Additionally, the pore size distribution was altered. These parameters influence the transport of fluids and the moisture regime in rock masses, which can serve as a precursor to physical and chemical weathering processes

Real-Time Prediction of Petrophysical Properties Using Machine Learning Based on Drilling Parameters.

The prediction of rock porosity and permeability is crucial for assessing reservoir productivity and economic feasibility. However, traditional methods for obtaining these properties are time-consuming and expensive, making them impractical for comprehensive reservoir evaluation. This study introduces a novel approach to efficiently predict rock porosity and permeability for reservoir assessment by leveraging real-time machine learning models. Utilizing readily available drilling parameters, this approach offers a cost-effective alternative to traditional time-consuming methods to predict formation petrophysical parameters in real-time. The data set used in this study was collected from two vertical wells located in the Middle East. It encompasses drilling parameters such as the rate of penetration (ROP), gallons per minute (GPM), revolutions per minute (RPM), strokes per minute (SPP), torque, and weight on bit (WOB), along with the corresponding measurements of porosity (ϕ) and permeability (k) obtained through core analysis. Three machine learning models, namely, decision trees (DTs), random forest (RFs), and support vector machines (SVMs), were employed and evaluated for their effectiveness in predicting porosity and permeability. The results demonstrate promising performance across the different data sets. All three models achieved correlation coefficients (R) higher than 0.91 in predicting porosity. The RF model exhibited accurate predictions of permeability, achieving R values surpassing 0.92 in the various data sets. While the DT model displayed slightly lower performance, with the R-value decreasing to 0.88 in the testing data set, the SVM model suffered from overfitting, with R values dropping to 0.83 in the testing data set. The novelty of this work lies in the successful application of machine learning models to the real-time prediction of reservoir properties, providing a practical and efficient solution for the oil and gas industry. By achieving correlation coefficients exceeding 0.91 and showcasing the models' efficacy in a dynamic testing data set, this study paves the way for improved decision-making processes and enhanced exploration and production activities. The innovative aspect lies in the utilization of drilling parameters for timely and cost-effective estimation, transforming conventional reservoir evaluation methods.

On the stress-dependent tight-rock permeability under anisotropic stress conditions

Permeability is a key parameter for characterizing an unconventional tight-rock reservoir and predicting hydrocarbon production from the reservoir. Because of the technical difficulty in accurately measuring extremely low tight-rock permeability, the permeability measurements have been commonly made in laboratory under hydrostatic (or isotropic stress) conditions. For unconventional reservoirs, stress distributions, however, are generally anisotropic. This paper presents a theoretical and experimental study on stress-dependent tight-rock permeability under anisotropic stress conditions. The theoretical development is based on the concept of effective stress and expresses rock permeability as an exponential function of the effective stress defined in this paper. The laboratory permeability data obtained under anisotropic stress conditions support the usefulness of the theoretical model for the stress-dependent permeability and demonstrate the importance of stress anisotropy in determining rock permeability. Considering that the effective stress is the only independent variable for determining the relationship between rock permeability and stress, we further propose a workflow to convert tight-rock permeability data collected under hydrostatic stress conditions to those for anisotropic stress conditions that are more realistic for field applications. A theoretical relation for upscaling a parameter characterizing the impact of stress anisotropy on local-scale permeability is also discussed as the first step to address this important upscaling issue.

Study on the Change Law of Pore Structure and Permeability of Coal Under Chemical Permeability Enhancement Technology

In order to deeply explore the permeability enhancement effect and permeability enhancement mechanism of the three chemical permeability enhancement technologies, the pore structure change and permeability enhancement mechanism of anthracite coal were studied from the perspective of coal pore structure. The following conclusions are drawn: the permeation effect of the four solutions from large to small is 99% CS2, 10% NaClO, 8% HF, 8% The total pore volume of HCl and HCl solution decreases after acidification, the pore volume of HF solution increases after acidification, the number of pores in the coal sample after oxidation of NaClO solution increases, and the micropores are transformed into mesopores, and the pore volume of CS2 solution increases after extraction, and the pore expansion effect is better than that of the other three solutions, and the pore volume with a pore diameter greater than 2 nm affects the flow of gas between pores, and the larger the pore volume, the higher the permeability. The pores with a pore diameter of less than 2 nm have little correlation with the permeability of coal and rock, and the micropores do not affect the gas flow

Study on the evolution of permeability properties of limestone under different stress paths

Abstract Stress path change has a great relationship with the effect of deformation and strength of rock. However, the underground rock body is in the engineering environment where the stress field, seepage field, and other fields are coupled to change, the law of fluid flow in the rock body is complex and variable. The change in the stress field has an important effect on the seepage characteristics of rock body; therefore, it is necessary to study the pattern of rock permeability evolution pattern by different stress paths. This study is based on the study of limestone, conducting triaxial unloading seepage mechanics experiments, the evolution of permeability properties of limestone specimens was analyzed based on the test results. The results show that in the conventional triaxial loading seepage test, the permeability of the limestone decreases before the rock stress reaches the peak intensity and increases after that. Increasing axial pressure unloading surrounding pressure compression section, permeability loss rate and effective stress are in line with the changing law of Gaussian distribution function. Under the action of constant axial pressure unloading surrounding pressure, with the increase in unloading amount, the permeability rate of change appears to increase slowly, and in the late stage of unloading section, the permeability rate of change appears to surge. Unloading section permeability change rate and cumulative unloading amount are in line with the law of change of the exponential function. Creep unloading pressure seepage test found that unloading pressure stage strain-time and permeability-time evolution characteristics are in line with the exponential rule of change. The experimental results of this study can provide an important experimental and theoretical basis for the permeability analysis of low-permeability rock body under complex stress conditions in underground engineering.

Three-stage hydrocarbon accumulations in the Middle Permian in the Central Sichuan Basin

The Middle Permain Maokou Formation (P2m) is a new region of natural gas exploration in the Sichuan Basin, is characterized by bioclastic limestone with localized dolomitization, and karst fractured-vuggy reservoirs. Currently, on the gas source, hydrocarbon accumulation process and control factors in the Sichuan Basin during the Permian are lacking. To bridge this gap, herein, we identified the filling sequence minerals inside the pores/vugs, along with the oil charge of the Maokou Formation using drill cores, thin sections, oil inclusion analysis, and U-Pb dating of calcite cements. The results showed that the reservoir space of the Maokou Formation was predominated by the residual dissolved pores/vugs, fractures, and dissolved fractures. The pores/vugs underwent four stages of mineral filling by very fine-fine (-crystalline, CC1) calcite → fine-medium calcite (CC2: from 256.4 ± 1.7 to 244.1 ± 6.3 Ma) → fibrous calcite (FC; ∼183.9 ± 8.2 Ma) → coarse-macro calcite (CC3; ∼171.5 ± 5.3 Ma). Combined with the homogenization temperature and salty of fluid inclusion, we considered that three stages of oil charge were present in the Maokou Formation reservoirs. The first stage involved the formation of paleo-oil reservoirs during the Late Permian to Early Triassic, corresponding to the high-maturity aqueous inclusions in CC2, with a homogenization temperature of 106.7°C–137.8°C. At that time, the oil generation from the Lower Cambrian Qiongzhusi Formation rocks peaked, and the generated hydrocarbons migrated upward into the Maokou Formation through the strike-slip faults in the basin center. The second stage involved the formation of paleo-oil reservoirs during the Early Jurassic. The Permian source rocks reached the oil generation window with hydrocarbon expulsion, which was consistent with the oil inclusions in FC. The third stage involved the formation of paleo-gas reservoirs during the Middle Jurassic to Early Cretaceous, corresponding to the high-density methane inclusions and bitumen inclusions occurring in CC3, with the homogenization temperature peaking at 151.9°C–178°C. The natural gas in the Middle Permian of the Central Sichuan Basin is predominantly sourced from the Lower Cambrian Qiongzhusi Formation mudstone and partially from the source rocks of the Middle Permian, indicating a significant source-reservoir conduit of the strike-slip faults in the basin center. The findings provide considerable baseline data to advance further research in the Sichuan Basin.

Study on the evolution of limestone damage and permeability under the tunnel driving stress path

The tunnel water inrush problems threaten the safety of tunneling. To understand the water inrush mechanism in tunnel tunneling, triaxial water seepage test and COMSOL numerical simulation were applied to study the water seepage law of tunnel surrounding rock according to the tunnel driving stress path. The results show that the permeability changes slowly, increases sharply and decreases sharply, respectively, during seepage and mechanical loading-unloading. However, during the σ1−σ3 active unloading stage, the permeability cannot return to the state before the plastic stage. The permeability presents a highly fitting exponential relationship with the stress of deviatoric and effective volume. During different loading and unloading stages, the index relationship is different, which is related to the rock damage degree. Through uniaxial cyclic loading-unloading acoustic emission test, it is verified that axial strain ε1 is related to cumulative AE count, that is rock damage degree. The damage variable D based on axial strain ε1 was established, and the permeability evolution law was effectively characterized by damage variable D. The permeability and crack evolution process cannot be directly observed during seepage test. The numerical model of real heterogeneous rock samples is established based on COMSOL. The simulated rock shear fracture feature is close to that of laboratory tests. In the numerical simulation of seepage, the evolution laws of damage, fracture and permeability in rock are effectively quantified. It is proved that the necessary numerical simulation can serve as an effective supplement to the laboratory test.

Analysis of fractures generated by faults at micro- and macro-scale and the influence on the secondary permeability: application to the Nevado del Ruiz area (Colombia)

This research contributes to the knowledge of the geothermal area of the Nevado del Ruiz Volcano (Colombia) by analyzing the secondary permeability and connectivity of fractures at microstructural and macrostructural level. Although the Nevado del Ruiz Volcano (NRV) area has had geothermal exploration studies for power generation since 1968, there is still no exploitation of its geothermal resources. The NRV geothermal reservoir is characterized by a low primary permeability and the presence of several geological faults crossing a tectonically active and complex region. The analysis was performed comparing a zone affected by intense faulting with another one characterized by the same lithology, but with less influence of faulting and located further from the volcano. Fractures were characterized at outcrops with the window sampling method, and petrographic analysis was performed to confirm the mineralogy of samples collected. At the microstructural scale it was found that faulting does not necessarily influence the interconnectivity of fractures, but it does influence their intensity, quantity, and strike. To analyze the influence of fractures on groundwater flow, it is suggested to consider three main aspects: secondary permeability, connectivity, and fracture intensity. The lithology of major geothermal interest in the NVR area (Pes) presented greater connectivity and fracture intensity, which, combined with the high foliation observed in field, increase its effective permeability. The secondary permeability of different lithologies in the NRV area ranged between 1.15 × 10–6 and 10.32 × 10–7 m2. Most of the hot springs were in areas of high macrostructural connectivity, supporting the idea that groundwater flow is dominated by the secondary permeability of rocks. Estimation of the secondary permeability and identification of areas of high fracturing and connectivity, contributes to the understanding of the NRV geothermal area, which is a key aspect when drilling for successful well production. The methodology presented is useful in the initial exploration phase in fractured geothermal reservoirs.

Restoration of Rock Permeability Degraded by Well Killing Fluid Using Ultrasonic Vibrations: Experimental Studies

The operation of oil production wells is accompanied by the invasion of well killing fluids into a near wellbore zone while well intervention which deteriorates rock permeability and decreases well oil rate. In order to restore the permeability of the rock in the near wellbore zone of the formation, it is proposed in this work to use ultrasonic alternating loading during well inflow stimulation. To study the effect of alternating loading on the permeability of rocks, a laboratory set-up is developed and filtration experiments are carried out. The rock studied was sandstone of medium permeability. The experimental studies included four stages: filtration of the killing fluid (calcium chloride solution) in the forward direction (simulating well killing); keeping the sample in conditions of pumped kill fluid; filtration of kerosene in the opposite direction (simulating an inflow stimulation) until the maximum possible restoration of permeability; filtration of kerosene in the reverse direction under ultrasonic alternating loading conditions for additional permeability restoration. It was revealed, that under conditions of ultrasonic alternating loading, the pore space of the rock, previously blocked by particles of the killing fluid, is unblocked and the permeability of the samples is restored. An analysis was made of the mechanism of blocking the pore space with the killing fluid and restoring the permeability of the rock.