To ensure the performance efficiency and long-term operational safety of the engineering barrier in deep geological repositories, it is of great importance to investigate gas migration behavior in the water-saturated bentonite subjected to decay heat generated by the nuclear waste. In this work, experimental investigations were conducted to find out influences of multi-step thermal cycles on variations

Understanding the behavior and composition of fracturing flowback water (FFW) can provide insight into in situ water–rock interactions, assessment of the success of the fracturing operations. FFW was collected from three wells (Z202-H1, Z203, and Z205) for up to 108 days after fracturing in the same area of western Chongqing, China. The samples were analyzed for the concentrations of various ions (Na+

The accurate determination of hydrate formation temperature (HFT) is an extremely vital step in the context of designing processes containing hydrates. Due to the prohibitive time and the expensive cost of the experimental procedures, some empirical and theoretical approaches have been developed for estimating HFT. However, most of these prior approaches are associated with a lack of generalization

The geometric complexity of the 3D pore-fracture system of tight rock at the pore-scale is a primary challenge for the prediction of gas flow. In this paper, the 3D pore-fracture systems of tight rock are reconstructed based on the representation unit volume (REV) of the intact tight sandstone and fractal fracture. A 3D regularized lattice Boltzmann model that considered the gas slippage effect is

Using supercritical CO2 as fracturing medium to develop shale gas not only improve the stimulation effect of reservoir, but also reduce CO2 emissions. To optimise the flow of shale gas into a wellbore, it is important to understand the flow characteristics of gas in the shale fracture system after reservoir reconstruction. To date, no research has been conducted on the effect of supercritical CO2 on

Permeability determines the exploration and development efficiency of the oil and gas field, while the pore structure directly affects the permeability of sandstones. Therefore, in the current study, the pore structure and permeability of sandstones were quantitatively analyzed from macro and micro perspectives. With SEM images at different magnifications, pore size distributions (PSD) were obtained

The effective thermal conductivity changes in the sediments during depressurization are significant for hydrate exploitation. But these changes cannot be measured directly because of the unavailable stable conditions during depressurization. In this work, in order to form the stable conditions for the measurements, soaking was designed to stabilize temperature and pressure in the sample after depressurization

Borehole instability in the petroleum industry is mainly because of mechanical, chemical, and thermal factors which result in substantial yearly expenditures. The essential part of analysing borehole stability is choosing an optimum rock strength criterion. Many rock strength criteria have been used for rock failure analysis, however all mechanical, chemical and thermal effects are seldom coupled with

Although the stress sensitivity of carbonate reservoir has been investigated extensively, that of saline-lacustrine fractured tight carbonate reservoir still remains to be fully understood. In this work, permeability stress sensitivity behavior of saline-lacustrine fractured tight carbonate reservoir was investigated based on steady state test and pressure attenuation method. Several core analysis

To investigate the interaction between coal and fracturing fluid and its influence on the pore structures of the coal, three commonly used water-based fracturing fluids were selected and used to treat Illinois coal. A series of low-temperature nitrogen ad-/desorption experiments and nuclear magnetic resonance measurements were conducted to comparatively analyse the evolution of the coal pore structure

Hydraulic fracturing operations have been widely used to enhance reservoir permeability during the extraction of oil, shale gas and tight sandstone gas. Recently, non-aqueous fracturing fluids, such as supercritical carbon dioxide and nitrogen, have been proposed as the potential fracturing fluid candidates due to their advantages of decreasing formation damage, conserving water resources and avoiding

The efficiency and safety of natural gas hydrate exploitation is significantly affected by the occurrence and distribution of hydrate and the seepage behaviors of gas and water in hydrate bearing sediments. We present the results from xenon hydrate formation and dissociation experiments with different salinities using quartz etching microfluidic chips. Direct visualization of hydrate growth morphology

Maintaining the fracture network created by hydraulic fracturing remains challenging because unpropped fractures close during production, resulting in shale gas production decline. Chemical dissolution is being implemented to maintain unpropped fracture conductivity, and the effect of oxidative dissolution on organic-rich shale may have the potential to maintain these fractures. In this paper, the

The Junggar Basin, Xinjiang has abundant coalbed methane (CBM) resources, and most of the CBM is found in the coal reservoirs with high dip angle (>50°), where the generation, accumulation and extraction of CBM significantly differs with flat coal reservoirs. This study clarifies the effect of high dip angle on the fluid pressure field, in situ stress field, permeability and gas bearing capacity of

With the development of coal-bed methane (CBM) mining technology, deep coal-beds have become the target of CBM development. In order to simulate changes in coal adsorption and permeability characteristics caused by increased mining depth, low-temperature liquid nitrogen adsorption tests, isothermal adsorption tests and triaxial seepage tests under rising gas pressure have been conducted. In this study

Fouling formation in gas dehydration units is performed mainly by gradual accumulation of sulfur-containing compounds and its corrosion products in glycol streams. High concentrations of iron-sulfur species in glycol media increase the fouling propensity on the tube surfaces of heat exchangers. Therefore, the factors affecting the fouling formation and their ranks were determined in a pilot plant gas

Shale is an extremely tight and fine-grained sedimentary rock with nanometer-scale pore sizes. The internal nanopore structure gives rise to not merely the ultra-low permeability of shale, but also the significant slip flow (non-Darcy) phenomenon. This study involves a second-order correction of the traditional Klinkenberg equation and its experimental verification, in consideration of the effect of

Particle Image Velocimetry (PIV) is a well established technique used to measure displacements in fluids. Proppant transport and placement is a crucial phase in the process of well completion to stimulate production in gas and oil reservoirs. Proppant (a granular material) is injected along fluids during hydraulic stimulation to prop fractures open after hydrocarbon production is initiated. This work

Plugging and diverting acid fracturing is an indispensable and promising technology that aims to enhance productivity for complex carbonate reservoirs. The key to success for this technology is the formation of effective plugged zones within preexisting fractures. However, because fracture pattern before and after acid-etching is quite different, the plugging behavior of fibers and particulates within

Sand production greatly influences reservoir stability and safety during gas hydrate exploitation in hydrate-bearing sediments (HBS). Gravel packing is an effective method for sand control. Median grain size ratio (D50/d50) values and sand migration of gravel pack are important factors in sand control during gas hydrate exploitation. This paper focuses on sand migration in samples with an optimal (D50/d50)

Water holdup measurement is always in the spotlight of the oil and gas industry. One way of determining water holdup in gas-liquid two-phase flow is through dielectric constant of flow. In this study, we proposed Superficial Dielectric Constant (SDC) and established the SDC model to describe the relationship between dielectric properties and water holdup. Firstly, we designed a Resonant Cavity Sensor(RCS)

The ultra-low permeability nature of shale reservoirs leads to an extended linear flow and necessitates horizontal wells with multi-stage engineered fractures to efficiently extract hydrocarbons resources. These artificially-generated and naturally-occurring fractures form complex networks that create complex flow regimes which control oil production. These fractures are neither identical nor equally-spaced

The periphery of the Huangling Massif is one of the principal prospecting regions of the Lower Cambrian shale gas resources in South China. The geological setting and ground surface conditions are complicated within this area, and the petroleum geological data is limited due to the low degree of exploration. A novel approach based on the regional geological survey and remote sensing data was proposed

An original approach to the problem of chemo-mechanical characterization of shale rocks is presented, which consists of combining grid nanoindentation technique, scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS), and multispectral image analysis. X-ray microanalysis of the major elements is performed over the indented region, resulting in high-resolution images of the spatial

Aiming at the “multilayer superimposed coalbed methane (MSCBM) system,” which is a widely developed CBM reservoir formation mode, a MSCBM production test device was developed. The initial reservoir pressure of the simulated reservoirs (coal seams Nos. I–IV) was 1.0, 1.4, 1.8, and 2.2 MPa, respectively. MSCBM production experiments were carried out using different numbers of gas-producing layers. The

In the shale gas vertical separation metering skid, after the shale gas is separated by the gas-liquid separator, the bottom sand-carrying sewage is driven by high pressure, and the high-speed flowing sand particles will cause serious erosion to the sewage valve. Given this problem, taking a production well in the Changning area as an example, the corresponding mathematical model, and a three-dimensional

N-Methyl-diethanolamine (MDEA) is a potential solvent to capture CO2 at high-pressure and high CO2 concentration conditions due to its high CO2-loading capacity and the pressure-driven nature of CO2-MDEA reaction equilibrium. However, no studies have been reported on packed column modelling and experimental evaluation of CO2 absorption process using MDEA solvent for high pressure and high CO2 concentration

Pipeline networks are the primary means of natural gas transmission, and assessing the gas supply reliability is of great significance for the safe and stable operation of pipeline networks. However, current assessment researches for the gas supply reliability are just conducted on the entire pipeline networks and based on the failed pipeline networks, i.e. the assessment process is static. The individual

The corrosion behaviour of X70 pipeline steel in CO2-containing formation water at various temperatures was studied in a high-temperature and high-pressure reactor via weight loss measurements, scanning electron microscope, X-ray diffraction, energy dispersive spectroscopy, and electrochemical methods. The concentrations of CO2 and ions in formation water at 30–150 °C were calculated. The equilibrium

To achieve efficient recovery of subsurface energy resources, a suitable trajectory needs to be identified for the production well. In this study, a new approach is presented for automated identification of optimum well trajectories in heterogeneous oil/gas reservoirs. The optimisation procedures are as follows. First, a productivity potential map is generated based on the site characterisation data

Impurity effects are an intricate issue in CO2 geological storage, involving both pre-dissolved impurities in the geological medium and co-injected impurities. Numerical simulations were carried out in this study to investigate the coupling effects of pre-dissolved H2S and different co-injected impurities (H2S, CH4 and N2) on CO2 sequestration in layered sour saline aquifers. The native H2S would be

Central Algerian Sahara hosts many prolific hydrocarbon accumulations in the Paleozoic successions. In this work a contemporary stress field of the Saharan platform has been evaluated using the dataset from recently drilled wells in El Agreb, El Gassi and Hassi Messaoud fields. A pore fluid pressure gradient of 0.56 PSI/feet is interpreted from the in-situ measurements in the Paleozoic reservoir units

The quantitative determination of the influence of the critical factors on the adsorption capacity of the shale is important for accurately evaluating its adsorption capacity under the geological conditions. The adsorption experiments are performed on both the dry and the water-saturated shale samples, and the Grand Canonical Monte Carlo (GCMC) simulations are carried out on both the organic and inorganic

The adsorption mechanism of carbon dioxide (CO2) in the coal matrix is significant in practical stability and migration process of CO2 into a coalbed seam. This study presents the kinetic investigation and the main controlling step of CO2 adsorption capacity onto Malaysian coals. The experimental data of CO2 adsorption were determined using a volumetric technique at 273, 298, 308, and 318 K and pressures

Pressure drawdown in a production well is a key parameter to control and optimize hydrocarbon production from the reservoirs. During production process in a stress-sensitive unconventional reservoir, there exist two competing mechanisms that are related to the pressure drawdown and impact the production: pressure gradient between the reservoir and production well and stress dependency of permeability

The physics of proppant transport in fractured reservoirs is of great interest to the oil and gas industry; nevertheless, the outcomes are controversial. This study provides a comprehensive reference for proppant transport findings. The various types of fracturing fluids and their carrying capacity were discussed. The factors affecting proppant transport based on the Plexiglass visualization cell were

Reservoir geomechanical parameters play a vital role in evaluating sanding potential, wellbore stability, and drilling performance for making decisions on development strategies of oil and gas fields. Compared to expensive experimental/laboratory investigations, the petrophysical log data-driven shear sonic velocity models are proven to be cost effective and quick to estimate geomechanical formation

Prediction of fracture initiation pressure (FIP) is an essential issue for safety drilling, fracturing evaluation and efficient production in shale gas exploitation. To quickly and accurately evaluate the FIP of a horizontal borehole drilled in anisotropic rocks, an analytical solution for borehole stress was first deduced based on the complex potential method and superposition principle. In combination

Accurate prediction of gas production is critical for the shale gas development. Compared with the complicated physics-based simulation, the decline curve analysis (DCA) models based on parameter linearization or direct curve regression are much more straightforward and efficient. However, the linearization method might be time consuming in obtaining the parameters, and the direct regression might

Exploration of shale gas has indeed changed the dynamics of the petroleum industry. Efficient drilling in shale bearing zones largely depends on the nature of drilling fluid that are used. Non-damaging drilling fluid (NDDF) has emerged as an important class of drilling fluids over the last decade due to its superior inhibitive nature that yields better wellbore conditioning, especially in formations

Multi-fractured horizontal well (MFHW) is commonly used in tight gas reservoirs to achieve commercial development, and the created hydraulic fractures are irregularly distributed and stress-sensitive in general. The Blasingame decline analysis method that can deal with the variable rate/BHP cases has attracted great interest. In this paper, a Blasingame decline analysis model of MFHW with irregularly

The dissociation curves of pore hydrate, conventionally depicted on the P-T plane, depend generally upon the adopted experimental conditions. In this paper, the experimental results are presented on the phase equilibrium conditions for the hydrate-bearing soils (HBS) at different initial water contents, amounts of the dissolvable salt and initial vessel pressures. It is shown that a unique relationship

The elastic wave velocities of hydrate-bearing sediments (HBS) are considerably affected by the content of free gas and hydrate. Although several existing models relate the free gas and hydrate saturation to acoustic velocities, the accuracy of these models is still uncertain because of the difficulty in determining the gas content. In this study, we acquired the gas volume fraction and acoustic velocity

Methane hydrate has the potential to become a high quality medium for gas storage and a special fuel because of its high efficiency for gas storage and its combustibility. It is important to study the factors that affect the combustion characteristics of methane hydrate. In this paper, the effects of gas content and ambient temperature on the combustion of methane hydrate spheres are investigated experimentally

The Cascadia Margin in the Pacific Ocean is a widely investigated region for oceanic gas hydrates. In this study, numerical simulation models are developed to simulate the flow of methane gas up fault zones in the Southern Hydrate Ridge of the Cascadia Margin. Three different hydrate formation scenarios, common to hydrate formation mechanisms in similar settings, are simulated. The tested scenarios

The present study aims at characterizing the sedimentological and petrophysical properties of the Middle-Late Miocene Mt Messenger reservoir in Taranaki Basin, New Zealand. It is a detailed study based on availability of sedimentological (petrography, SEM and XRD), well log data (gamma ray, neutron, density, sonic, shallow and deep resistivity, PEF and RFT logs), in addition to conventional and special

The utilization of acid has been approved as a potential approach to enhance Stimulated Reservoir Volume (SRV) by creating secondary pores and microfractures in shale reservoirs. This paper proposed an acid soaking technique to quantify the generation of microfracturing behaviors. Two types of core samples from distinct shale depositional environments, namely Longmaxi carbonate-rich, and Yanchang clay-rich

Stimulated reservoir volume (SRV) seldom provides an actual producible reservoir volume in gas shale reservoirs. It is determined by analysing microseismic events induced by a network of hydraulic fracture and reopened natural fractures. However, the occurrence of noncontributory microseismic events leads to an overestimation while the presence of natural fractures leads to an underestimation of producible

Petrophysical reservoir quality assessment is achieved through several methods based on the pore volume, connectivity, and conductivity. Reservoir quality index (RQI), and reservoir flow indicator (FZI) are among the most important parameters that are used for this assessment. In addition, the effective pore radius of Winland (r35) is additional technique that is applied based on mercury injection

The present study proposes a new burst capacity model for corroded oil and gas pipelines based on extensive parametric three-dimensional (3D) elasto-plastic FEA validated by full-scale burst tests. The corrosion defect is assumed to be semi-ellipsoidal-shaped in the proposed model as it better approximates the geometry of real corrosion defects than the commonly used rectangular idealization. Based

Current gas rate decline analysis methods in boundary-dominated flow (BDF) are mainly based on Arps' empirical decline models, or the liquid-based analytical models associating with pseudo-variables. Recently, Stumpf and Ayala (2016), and Wang and Ayala (2020) demonstrated that the decline exponents (b) used in Arps’ hyperbolic model can be rigorously estimated in advance for both constant and variable

The prediction of unconfined compressive strength (UCS) of oil well cement class “H” based on the artificial neural network (ANN) modeling approach is presented in this study. 195 cement samples were embedded with varying dosages of strength enhancing pre-dispersed nanoparticles consisting of nanosilica (nano-SiO2), nanoalumina (nano-Al2O3), and nanotitanium dioxide (nano-TiO2) at various simulated

Gas hydrate, as an alternate hydrocarbon source, has attracted significant attention in past decades. A precise estimation of permeability of the gas hydrate-bearing formation is essential for predicting the flow behaviors and the associated gas production performance. In this research, the influence of gas hydrate saturation on pore structural properties and then affect permeability was investigated

Coal seams are usually fractured reservoirs where the factures/cleats are fluids flow channels, and the matrix blocks serve as the storage space. The gas transport within the matrix has crucial impacts on the variation of cleat aperture and thus affects the reliable determination of coal permeability. Most literature on laboratory measurements and the development of relevant analytical models focus