The choice of the flow velocity in EGR thus becomes important since higher injection rates could lead to premature mixing of the fluids and lower injection rates generally provide longer resident times for the fluids in contact and indirectly increases the mixing of the gases. Additionally, the medium peclet numbers mostly indicate the best injection rates that translate to a smoother displacement

Shale gas wells with high production rates usually have large amounts of hydraulic liquid retention, which can cause aqueous phase trapping (APT). However, the APT can be auto-relieved after a well shut-in for a certain period. To clarify its mechanism, the experiments of shale permeability during liquid imbibition and diffusion were conducted. Then, theoretical analysis was interpreted. Samples include

Characterized by rock sediments and complicated storage mechanisms, shale reservoir development is to create flow systems comprised of complex natural fissures and hydraulic fracture stimulation such that the hydrocarbons in the reservoir can be recovered economically. The prediction of shale reservoir production performance is critical for reservoir management and challenging due to the compounding

Coalbed methane (CBM) is mainly adsorbed in coal reservoir. To explore the methane (CH4) adsorption mechanism in coal, this paper investigated the relationships among CH4 adsorption characteristics and microstructure and chemical composition of the coal samples through different solvent treatments. The results indicate that after THF and CH3CH2OH treatments, aromatic and aliphatic functional groups

Hydraulic fracturing combined with horizontal drilling has resulted in the rapid development of unconventional shale gas production during the last couple of decades. These shale gas fields have faced challenges in terms of bacterial control and pitting corrosion attacks. In the present work, laboratory and on-site corrosion tests were performed to investigate the corrosion behavior of two gathering

Relative permeability is one of the most important parameters in reservoir modeling. However, measurements of relative permeability in unconventional reservoir rocks are rare, and the influence of relative permeability hysteresis on reservoir studies has not previously been addressed. This paper presents a systematic investigation of gas-water relative permeability and hysteresis based on a laboratory

Industry needs techniques for expediting understanding on shale reservoir deliverability and spatial drainage. Horizontal wells are currently the option of choice for these investigations but their early adoption is costly and time consuming. Stimulated and flow tested vertical exploration wells could address this challenge. Multi-domain data from one of the initial Eagle Ford stimulated vertical wells

The permeability of methane hydrate (MH)-bearing sediments is closely related to the exploitation efficiency of MH deposits. During the exploitation of MHs, the stress state of hydrate-bearing reservoirs is complex, and stratum deformation may occur simultaneously. Both the change in the stress state and stratum deformation may influence the permeability of hydrate-bearing sediments. In this paper

We investigated the effect of mixtures of commercial nonionic surfactants Sintanol ALM-7 (A7), Sintanol ALM-10 (A10), Surfynol 465 (S6), Surfynol 485 (S8), and well-known kinetic hydrate inhibitor Luvicap 55W (sample P) on nucleation and growth of sII gas hydrate. The ramp method (cooling at a constant rate of 1 °C × h−1) was employed to determine hydrate onset temperature and subcooling of individual

Macrolithotypes control the pore-fracture distribution heterogeneity in coal impacting gas adsorption, diffusion coefficient, and the gas flow. However, the behaviors that are impacted by coal macrolithotype are traditionally ignored and the drainage radius that linked to the macrolithotype contributions are lack of systematic research all the way. Thus, to evaluate the gas production relationship

Understanding the complex transport behavior of methane in coal matrix pores is very important for coalbed methane exploitation. One important approach is to model the transport process of methane in coal matrix nanopores. In this work, we modelled the coalbed methane transport process in coal matrix nanopores, coupling gas adsorption, real (i.e. non-ideal) gas and gas slippage effects, and a new method

Hydraulic fracturing technology is the most effective stimulation method to develop hydrocarbons in tight reservoirs, but the invading of fracturing fluid into the reservoir matrix often causes permeability damage, resulting in reducing the effectiveness of the stimulation treatments. Therefore, in this paper, for tight cores with permeability of 0.10 × 10−3μm2, 0.05 × 10−3μm2 and 0.01 × 10−3μm2, the

Worldwide methane hydrate exploration activities have entered a new stage after the real extraction tests in Japan (2013, 2017) and China (2017). However, from the current technological development stage to the next commercial production stage, there still exist a wide gap: complex underground reservoir conditions and flow parameters. Therefore, the target of the current study is to investigate the

As for deep fuel exploitation of coal and gas,it is practical to study the gas flow characteristics of coal by considering a fractured medium. Coal samples containing different fracture networks were obtained in laboratory. The fracture network was quantitatively classified by an industrial computed tomography test. Several gas flow tests were conducted and classic permeability models were investigated

Hydraulic fracturing is an important technology widely applied in engineering practice for the exploitation of unconventional oil and gas resources. Further research on its mechanism has the potential to advance the development of unconventional reservoir exploitation. In this study, previously acquired experimental data, including surface fracture image and fluid pressure curve, were used for modelling

For matrix acidification in carbonate reservoirs, the use of chelating agents can avoid the problems associated with conventional acids, such as excessive acid-rock reaction and extreme corrosion on a well tubular. L-glutamic acid, N, N-diacetic acid (GLDA) has been used as a chelating agent for carbonate reservoir stimulation owing to its high water solubility, effective dissolution effect on carbonate

One of the main purposes of hydraulic fracturing in unconventional resources such as shale is to improve the connectivity between existing natural fractures and the production well. Since the inherent permeability of shale is extremely low, this newly formed fracture connectivity provides faster paths for the hydrocarbon stored in preexisting natural fractures. We performed numerical simulations of

CH4-CO2 replacement has been considered as a method for methane production from hydrate-bearing sediments to maintain sediment stability. Sediment stability has been studied at both the particle scale and mesoscale. However, the shear stiffness of sediments has not yet been explored. Moreover, the effects of CO2 and CO2-N2 mixtures as injection fluids on sediment stability remain unclear. Thus, this

In this work, we opted for the use of CO2 gas for the respective experiments, due to its greater solubility in water when compared to hydrocarbons, as well as possible applications in pre-salt oil fields (such as the Libra field), where the amount of CO2 varies between 40-80%, obstructing the pipelines in the CO2 capture stage. In this context, the objective of this work is to obtain organic salts

In this study, an experimental system in which small core devices with different configurations are connected in series was designed, and high-intensity gas injection and production experiments (3 groups, 28 times) were conducted to quantify the per-cycle gas loss (difference between the amounts of injected and produced gas). These experiments reveal that the lost gas fraction is positively correlated

Drilling complications, which are usually hard to be discovered in time using the traditional surface detecting methods, result in much time and money wasted in handling these problems. Restricted to data transmission speed with the measurement while drilling (MWD), downhole measured data is usually ignored in downhole complications detection. And the surface detection methods with some pressure and

Spontaneous imbibition behavior gained popularity several decades ago which led to widely exploited application in fractured reservoirs. Recently the imbibition behavior of unconventional reservoirs has attracted a good number of researchers and field engineers to pay attention and research more on how to enhance recovery through imbibition behavior. Despite the numerous studies that have been conducted

The evaluation of the pore structure of tight oil and gas reservoirs has great significance for the characterization of the reservoir properties and the prediction of reservoir productivity. Fractal analysis is an effective method commonly used to evaluate reservoir pore structure. In previous studies, the fractal dimension of nuclear magnetic resonance (NMR) transverse relaxation time (T2) distribution

To improve the general understanding of diffusive processes in coal and investigate if representative reservoir properties can be estimated from measurements on crushed coal particles, adsorption and desorption experiments on crushed samples and large, intact core samples are carried out. Diffusion properties are analysed for methane, carbon dioxide and nitrogen up to a pressure of 10 MPa at a temperature

The stratification split grouting foam mortar method (SSGFM) was first proposed to stimulate the low-permeability gas hydrate reservoir through constructing the fast flow channel for enhancing gas production. Based on the low-permeability hydrate-bearing sediments (HBS) at SH2 site in the Shenhu area of South China Sea, the foam mortar layer (FML) reservoir model was constructed. The numerical simulation

Hole cleaning and cuttings transport play a vital role in the drilling operation. Various drilling problems such as a reduction in penetration rate, an increase in the torque and drag, and an increase in the potential of differential sticking are often related to poor cuttings transport from a wellbore. Multiple parameters, including the fluid rheology, mud velocity, cuttings size, and drill pipe inclination

Compared with traditional fossil fuels, gas hydrates have vast reserves, cause little pollution, and are an essential strategic energy resource. Pipeline transportation is critical to realize the development and utilization of natural gas hydrate resources. The Eulerian multiphase flow model within the computational fluid dynamics software FLUENT was employed to calculate gas–liquid–solid flow, taking

DC stray currents may induce corrosion on buried carbon steel pipelines transporting methane even if in cathodic protection. According to international standard, anodic interference is unacceptable if the IR-free potential is more positive than the protection potential (-0.85 V CSE). But, duration and magnitude of the anodic peak is not defined. This paper describes results of laboratory tests performed

Shale is affected by temperature and loads in deep mining, shale gas extraction, underground disposal of nuclear waste, and other shale projects. This paper aims to investigate the effects of thermal treatment on the physical and mechanical properties of shale. The uniaxial compression test and acoustic emission (AE) monitoring were conducted on shale specimens with different bedding plane inclinations

Landslide occurrence is a major consequence of seismic activity in uphill ground conditions. There effects range from minor damage to severe malfunctioning of local infrastructure. Particularly for transport systems such as underground gas transmission pipelines, the nature of landslide phenomenon is usually catastrophic, thereby necessitating a detailed design analysis for ensuring structural integrity

To the petroleum industry, the cation exchange capacity (CEC) is one of the critical petrophysical parameters of the rock-gas-fluid system and the response of well logging tools. The widely used laboratory protocols for CEC determination (wet chemistry methods) came mainly from soil science, but with slight or even without modifications are being applied to organic-rich mudstones (shales). However

When drilling through naturally fractured reservoirs, the remediation of drill-in fluid loss needs to be designed by taking both fracture plugging and formation damage into account. Lost circulation materials (LCMs) should be implemented efficiently to minimize the solid-laden fluid invasion into the fractures during the development of fracture plugs. This study investigated the effects of three LCM

Nuclear magnetic resonance (NMR) severs as a nondestructive and relative new technique that has been widely used in characterizing reservoir fluids and pore size distribution (PSD) of coals. Conventionally, pore fluids in coals are classified into movable fluid and irreducible fluid based on a single NMR T2 cutoff value (T2C). However, the single NMR T2 cutoffs model has some apparent defects in pore

Production of methane gas from the methane-hydrate-bearing layer below the deep-ocean floor is expected to be crucial in the future of energy resources worldwide. During the methane gas-production phase from the methane hydrate with the depressurisation method, the depressurising zone around the production well will lose strength, causing a potential geohazard. In this study, a bio-mediated treatment

This paper focusses on sequence stratigraphy of coal-bearing strata, coal petrography, coal chemistry, and the CH4 adsorption capacity of the Badaowan Formation in Santanghu Basin, China. The comprehensive coal characteristics of 12 coal samples were determined, coupled with maceral composition, proximate analysis, elemental analysis, reflectance (Ro), and high-pressure CH4 adsorption. The results

High performance water removal plays a significant role in restoring the gas production when water invasion happens to tight gas reservoirs. In this paper, core samples with the air permeability in range of 0.01–1 mD were selected to investigate water removal behavior in tight gas reservoirs. Meanwhile, the gas flow capability during the process of water removal was discussed. The water desaturation

Inhibiting shale hydration is crucial for wellbore stability in oil and gas drilling operations when using water-based drilling fluids (WBDFs). In the study, a hydrophobically modified cationic oligoacrylamide (HCOA) was employed as a potential shale hydration inhibitor. It was prepared by precipitation polymerization of acrylamide (AAm), methylacrylethyl trimethylammonium chloride (DMC) and octadecyl

The Yuka depression is one of the most important energy production bases in the Qaindam Basin. Although shales in the 7th member of the Dameigou Formation (J2d7) are key members of Middle Jurassic Petroleum System, organic geochemistry and petrography of different rock facies have not been fully analyzed. In this study we evaluate hydrocarbon generation potential of the J2d7 by applying integrated

This paper presents a new cuttings transport model that captures the time-dependent effects of pipe rotation, drillpipe eccentricity and annulus blockage on hole cleaning. By integrating the time-dependent model with well construction data, the level of cuttings deposition along the trajectory of the wellbore can be simulated in real-time. The model recalculates its hole cleaning assessment at every

Perforation is the key to the successful implementation of hydraulic fracturing. The research on perforation mechanism is of great significance to perforation planning, completion design, hydraulic fracturing design, and proppant migration analysis. In this paper, a finite element model for simulating crack initiation and propagation in the presence of multiple perforations is established based on

The aim of the study was to analyse the effect of temperature on the sorption and diffusion of CO2 and CH4 on hard coal. Four coal samples, characterized by various degrees of coalification, were used in the research. The sorption measurements were carried out in three temperature values: 278 K, 313 K and 353 K and for the consecutive pressure values of 1 bar, 5 bar and 15 bar. Langmuir's sorption

The response of gas condensate reservoirs is directly influenced by heterogeneity. In such reservoirs, condensate is created around wellbore areas, when the reservoir pressure falls below the dew point pressure. Consequently, the distribution of this condensate bank makes fluid flow in the reservoir even more complicated by changing rock-fluid properties (e.g., relative permeability). This alteration

Overgeneration of wind energy conversion systems represents a grid issue, limiting the growth of renewable energy utilization. Alternative fuels utilization such as liquefied natural gas is emerging as a new market with a big potential in freight transport. In order to mitigate wind energy production curtailment, a power to liquefied synthetic natural gas process is proposed. Solid oxide electrolyser

The Archie model is empirical because it is based on curve-fitting methods, while the Geometric Factor Theory (GFT) is a physics-based porosity-conductivity model. Both these are used to compute water saturation (Sw) in simple Archie rocks (clean sandstones). Studies considering Archie’s work demonstrated that Archie equation was not applicable to carbonates and shaly sands, and all the scientifically

Nitrogen is a component that often needs to be removed from natural gas. A dual-reflux pressure swing adsorption (DR PSA) technology with activated carbon as the adsorbent was explored for N2 rejection from a binary mixture of 75 mol% CH4 and 25 mol% N2 via non-isothermal numerical modelling. The performance of the four DR PSA configurations (PL-A, PH-A, PL-B and PH-B) was studied by varying the following

The pore structure and coal matrix compressibility evolution law and their influencing factors of middle-high rank coals was evaluated based on the combined application of high pressure mercury injection, low-temperature nitrogen gas adsorption and low-temperature carbon dioxide adsorption. The middle-high rank coals are dominated by macropores and micropores, along with lower developed mesopores.

Hydrogen is considered as an alternative to fossil fuels that is practically unlimited, do not possess intermittency problems as wind/solar, and leads to zero carbon-emissions in its pure form and thus improving the air quality with respect to many other alternatives such as fossil fuels (i.e., natural gas streams). It is also an essential component in most CO2 to hydrocarbon conversion techniques

This study investigates the micropore-mesopore spectrum in gas shales by augmenting two different pore size distribution calculation methods using two probe gases in low-pressure sorption analysis. The Barakar Formation shale samples collected from Wardha and Asansol belonging to two key potential basins in India, namely Wardha and Raniganj, were studied to identify possible variations in pore attributes

Thermal stimulation methods have been investigated to enhance gas extraction from the high maturity shale recently. In this paper, a Longmaxi shale core sample, with vitrinite reflectance = 2.8%, was selected for canister tests to investigate the gas desorption process first at 55 °C and then switched to 110 °C. A mathematical model (self-similarity) was proposed to mimic the gas decaying process in

Although the exploration and development of tight gas have made great progress, the quantified study on gas migration and accumulation in sweet spots of tight gas reservoir is still limited. In this work, a computer program is developed to conveniently describe the different shape of sweet spots and the fractures in tight reservoir. Then, gas migration and accumulation processes are simulated, and

Temporary-plugging-and-diverting fracturing (TPD fracturing) is widely used to enhance hydrocarbon recovery from unconventional reservoirs. During TPD fracturing, diverters are injected to prevent the propagation of the previously formed fractures, then divert the fracturing fluid into the unstimulated zones. However, the influence of the fracture morphology on the diversion remains unknown. This study

Leak detection in pipelines has been a prevalent issue for several decades. Pipeline leaks from sources such as small cracks and pinholes are termed chronic leaks, as they have the potential of going unnoticed for long time periods, causing both economic losses and environmental damage. Literature lacks a comprehensive review of chronic leaks, especially under subsea or arctic conditions. Therefore

Slugs are intermittent structures observed in horizontal co-current gas-liquid two-phase flow. Published data examining horizontal flow indicate the existence of intermittent sub-flow patterns. There is limited work performed on the study of this sub-categorisation. This paper presents a method, exploiting non-intrusive Electrical Capacitance Tomography (ECT) measurements, to assess and to characterise

This work investigated buckling resistance of an X80 steel pipe containing a corrosion defect under axial compressive loading by finite element analysis. A 3-dimensional numerical model was developed to determine parametric effects on buckling behavior of the corroded pipeline. These included dimension of the corrosion defect (i.e., length, depth and width), pipeline geometry (i.e., outer diameter