In this study, the severity of slugging is assessed by predicting maximum slug lengths (MSL) quickly using the random forest (RF) algorithm based on the geometric features of well trajectories for a shale gas field. Severe slugging is one of the critical issues production engineering-wise because it causes operation shut-down. Thus it should be predicted for proactive measurements. A total of 5033

Polymeric membranes with metal-organic frameworks (MOFs) holds great potential for gas separation. However, finely tailoring the adhesion between MOFs and polymer matrices is crucial in reducing the membranes defective structure. The partial inorganic structure of MOFs limits the interaction with the polymer matrix, which tends to agglomerate on the membranes. Herein, an interfacial strategy is reported

The existence of pipeline defects in oil and gas gathering pipelines predisposed the pipeline to rupture under the synergistic effects of local micro–turbulence and electrochemical corrosion. Here, a combination of experimental and simulation methods was proposed to facilitate the investigation of CO2 corrosion and the mass transfer process in pipeline defects. The corrosion kinetic characteristics

Electromagnetic (EM) methods have provided an alternative means of detecting and estimating gas hydrate, especially in places where hydrates have been established to exist but the gas hydrate shows no bottom-simulating reflection. However, most EM numerical studies being done focused on surface/seafloor Controlled Source Electromagnetic (CSEM) studies with little consideration for borehole EM studies

Sulphate reducing prokaryotes (SRP) cause hydrogen sulphide (H2S) generation in some waterflooded hydrocarbon reservoirs that is known as microbial reservoir souring or biosouring. The H2S generated in-situ by SRP is toxic and corrosive that adversely affects the quality, production, and economy of oil fields together with negative environmental impacts. Various chemical, biological, and microbial

In many oilfield applications, gas-liquid (GL) flow modeling is required. One of these applications is predicting the uncontrolled hydrocarbon flow through a wellbore after a blowout, referred to as the worst-case discharge rate (WCD rate). It is common to see annular flow patterns in a wellbore during a blowout, especially when the superficial gas velocity (Vsg) is high and the superficial liquid

Coal seam gas drainage is not only the effective measure for gas outbursts control, but also has the great significance for the use of gas energy and reduction of greenhouse-gas emissions. Coal permeability is the key parameter of gas drainage, and the permeability model of mining-damaged coal has the important theoretical guidance value for gas drainage in low permeability coal seams. In order to

Due to the decrease of reservoir pressure, the elemental sulfur deposits in sour gas reservoirs, leading to the reduction in the reservoir porosity and permeability. It can also impact the transient pressure and rate behavior of gas wells, which is always reflected in pressure and flow rate type curves. However, few studies focus on transient analysis of multi-fractured horizontal wells affected by

The conventional water-based fracturing fluids have such defects as large water consumption, serious environmental pollution and water-sensitive damage to reservoirs in the development of tight oil. In this study, a novel anhydrous CO2 fracturing fluid system was constructed with the compositions of 7 wt% polydimethylsiloxane (100 cs), 5 wt% ethanol and 88 wt% liquid CO2. The viscosity of the system

An understanding of the mechanical properties of reservoir shale is of great significance for the efficient development of shale gas. Both marine and continental shale gas reservoirs in China have considerable development potential, but their different depositional environments may lead to substantial differences in their mechanical properties, which can result in production efficiency differences

Inorganic scale produced from shale reservoir oxidation during hydraulic fracturing will block pores and fractures, thus hindering the multi-scale transportation of shale gas. The results show that the cations produced after soaking in distilled water mainly consisted of Ca2+, Mg2+, Na+, K+ and Fe2+. Pyrite and chlorite contain reduced Fe, and the oxidized solution dissolves the reduced iron in shale

We used a stochastic 3D pore-scale simulation approach to statistically elucidate the effect of stochastic pore connectivity on permeability and hydraulic tortuosity of highly heterogeneous porous media such as carbonate rocks. The novel nature of our workflow lies in the generation of multiple 3D pore microstructures of the same effective porosity, pore size distribution, number of pores, but different

Long-distance energy pipeline pass under roads, subjecting them to repeated stress and posing pipeline safety problems. To simulate the effects of vehicles driving over energy transmission pipeline, this paper examines large-caliber buried pipelines in the suburbs. In this study, a mechanical action model of vehicle-soil-pipeline (VSP) interactions to transform the process of a vehicle driving into

Decline curve analyses (DCA) and rate transient analyses (RTA) are widely used to characterize the fluid flow through porous media and forecast future production. Oil and gas production data are routinely analyzed for history matching and optimizing the well stimulation methods in hydrocarbon exploration and production lifecycle. However, outliers add significant uncertainty and non-uniqueness to results

We have recently shown that molecular hydrogen generation from organic matter occurs at high maturity levels (vitrinite reflectance 3–5%) in Lower Cretaceous shales of the Songliao Basin. To evaluate and extend these implications to a wider range of source rock types and organofacies, we report on two Paleozoic maturity suites from Australia, namely the Permian Patchawarra Formation (fluviodeltaic;

Global warming is a major concern of today's world that mostly stems from greenhouse gases (GHG) emissions among which methane (CH4) has the second highest potential to cause such a problem. Among various types of discharging CH4 into atmosphere, fugitive emission from the natural gas (NG) supply chain has a significant contribution. In this study, methane emission from the pressure reduction station

In view of most wells are completed by casing pipe in oil & gas exploration and development process, it is imperative to extend the application of borehole acoustic reflection imaging (BARI) from open to cased boreholes. To understand the characteristics of signals in borehole acoustic imaging, we study the radiated and reflected elastic waves in an open and cased borehole through numerical simulations

Here, we analyzed geochemical indices of gases from core samples of permafrost table and evaluated data acquired from electric survey at the field of the Nadym-Pursk petroleum-bearing region. The Nadym-Pursk region is located in the northern West Siberia that is presently the major object of raw hydrocarbon (HC) exploration. The geologic exploration practice has demonstrated that the seismic survey

Thermal stimulation is a common measure used to improve the decomposition efficiency of natural gas hydrate. However, the conventional thermal stimulation methods require considerable investments in wellbore construction. According to the penetration mechanism of the torpedo anchor, the self-entry energy compensation device (ECD) is innovatively proposed to replace the existing wellbore platform. The

Hydraulic fracturing is one of the effective means to increase shale gas production, during which, proppant was widely used to support fractures to form stable seepage channels. Following which changes in permeability are restricted by the compaction and embedding of proppants, so studies on the impact of proppant on the fracture conductivity are highly desirable. In this paper, we discussed first

Hydrogen is a carbon-free fuel that can facilitate the progress of achieving net-zero emission. The use of the existing natural gas pipelines for hydrogen transport is an essential strategy to reduce the investment required for hydrogen distribution. However, gas transmission pipelines are generally comprised of steels that are susceptible to hydrogen embrittlement (HE). The failure of steel pipes

The current direct method of coalbed methane (CBM) content determination may underestimate the CBM content due to the negligence of lost gas in the borehole drilling stage of coal sampling, thus causing inaccurate evaluation of CBM reserves. In this work, considering the gas flow in coal body around the borehole before the coal sample is drilled down and exposed to air, the advanced lost gas in the

Horizontal well drilling and hydraulic fracturing technologies play an essential role in improving gas recovery from shale reservoirs. However, they are expensive technologies and resource intensive production strategies. Optimization design of horizontal well spacing and fracture stage placement helps in striking a balance between gas production and economic benefits. However, previous researches

A significant amount of hydrocarbon exists in naturally fractured formations. Due to the limitations of classical reservoir evaluation methods, the ongoing researches have focused on the analysis of production data to describe reservoir dynamic. Among the existing methods, the flowing material balance (FMB) technique brings a straightforward and accurate method of reserve estimation. Often, the same

Accurate assessment of the formation rock permeability and porosity is crucial for geotechnical applications. For tight formation rocks, separate measurements of permeability and porosity result in high time costs and degraded accuracy. This contribution presents an improved straight-line method that allows simultaneous permeability and porosity determination in a single pulse-decay measurement. In

The application of supersonic gas separation technology to remove carbon dioxide (CO2) from natural gas is an emerging concept; however, the microscopic mechanisms of CO2 condensation remain unknown. The accuracy of various CO2 flexible force field models is evaluated in this study, and the CO2 nucleation and growth processes are elucidated using molecular dynamics simulations. The results show that

Numerous models have been proposed to address the time-delayed wellbore collapses or untimely mud losses that have been widely reported in the field. There is still reluctance in applying them in real-time field operations due to their complex mathematical appearance. In this technical note, we address the effective stress solutions for short- and long-term wellbore stability analysis. We present the

Permeability is an important indicator of coalbed methane production. Previous classical theoretical permeability models under unconstrained boundary conditions have difficulty matching experimental results. Consideration of the actual cleat geometry can explain the non-equilibrium evolution of permeability to some extent, but the matrix swelling strain ignores the impact of damage effects. In this

Preventing hydrate crystallization in drilling fluid is the key to ensure the safety of deep water drilling. In this work, hydrate inhibition effect of nano-silica in deep water drilling fluids was measured and compared with the typical hydrate inhibitors containing KCl-PVP and EG-PVP. The three phase equilibrium and the formation kinetics of CH4 hydrate in the drilling fluids were measured. The micro-morphological

The efficient development of shale reservoirs relies on multi-stage hydraulic fracturing technology in horizontal wells involving the difficulty of multi-scale flow for either gas or water phases, which is characterized by the changes in the stress and temperature fields. The original simulation methods are unable to accurately solve the multi-physics field-coupled problems under such complex mechanical

Microporous structure and pore fluid are two important components of poroelastic rocks that influence the variation of rock modulus. Cracks are special microstructures that are more likely to be compressed during wave propagation than stiff pores, resulting in squirt flow. In addition, the distribution of different fluids, such as water and gas, may be characterized by patchy saturation and generate

Due to the cooling effect of natural gas throttling, spontaneous condensation will occur in the throttle valve, which may affect pipeline system efficiency. However, the condensation characteristics (such as nucleation rate and condensation rate) remain unclear, and the traditional method based on the isenthalpic hypothesis can hardly solve this non-equilibrium issue. Based on the geometry differences

CO2 replacement is a promising technology that simultaneously produces methane and carbon dioxide sequestration. In this work, a novel gradual heat injection enhanced replacement method (GHIR) was proposed to improve the methane production from natural gas hydrate sedimentary layer. The effects of heat injection mode on methane recovery, energy efficiency and the optimal operating conditions of GHIR

Since methane is an important component of shale gas, its confined phase behavior is significant to understand the essential mechanism leading to the fluid occurrence and hydrocarbons production. We studied the confinement impact of shale inorganic nanopores with pore sizes of 2–20 nm, for temperatures at phase equilibrium (120–190 K) and reservoir condition (325 K) using Monte Carlo molecular simulations

In this study, in order to investigate the effect of the underlying pore-scale processes on continuum scale simulations of porous media dissolution, we improve the standard Lattice Boltzmann method using Quadtree grid refinement approach to simulate fluid flow and reactive transport through large domain sizes. Our results have shown considerable computational improvements up to 80% in simulation time

This study focuses on the investigation of the nonlinear flow behaviour along rough-walled fractures with contact areas in the framework of the lattice Boltzmann method. The numerical results indicate that the fracture surface roughness controls both the advective aperture and the eddy aperture in the analysis of pressure, velocity, and vorticity fields. The eddy volume fraction increases from 28%

Surface atom functionalization and the variation of aliphatic/aromatic structures within coal macromolecules are key factors to determine the pore structures within coalification. The characteristics of nano-micron scale pore structures were analyzed with the aid of coupled fluid intrusion and molecular probe technologies. Results indicate that the cleavage of long-chain aliphatic structures enhances

A systematic approach for generating a stochastic void geometry with controllable shape features is proposed for more realistic numerical modelling of porous rock materials. The numerical model (a finite-discrete model) is established by integrating zero-thickness cohesive elements with finite solid elements, to trace the progressive fracturing and failure behaviours of porous rocks. A series of Brazil

Natural Gas Hydrate (NGH) is widely discovered in silty sediments with a high compressibility in the South China Sea. The permeability reduction in these reservoirs during depressurization is inevitable. Here, we innovatively take the effect of permeability reduction into account to improve the accuracy of production forecast and suggest the optimal production pressures for two different typical reservoirs

This paper first presents so-called unified Gaussian solutions for the spatial advance of diffusion transients triggered by a sudden change in pressure, molecular mass concentration and/or temperature. The mathematical description with a Gaussian solution for the pressure transient is similar to that for molecular diffusion and quantifies the diffusion of pressure into the reservoir space due to a

This study aims to understand the Sulfide Stress Cracking (SSC) resistance of API carbon steels exposed to wet sour environments containing CO2. A mini-pipe specimen was cut from API grade tubulars and placed in an SSC test cell to perform the investigation. The specimen was highly strained and internally pressurized while exposed to the corrosive environment for seven days. The partial pressure ratio

Uncontrolled and excessive gas emission may affect normal production and even result in serious disasters such as gas explosion and coal and gas outburst. To find out the essence of abnormal gas emission under mining induced stress, in this work, we conducted experiments on gas emitting from coal cores under mining-induced stress paths, and systematically discussed the controlling mechanism of stress

A shale gas reservoir has complex mineral components, bedding planes and micro-cracks, thus being of inherent heterogeneity and anisotropy. The roles of bedding planes in hydraulic fracturing performance have been deeply studied, but the effects of rock inherent heterogeneity induced by mineral components are not well understood. This paper establishes a two-dimensional particle assemblage model to

Fracture morphology of shales represents the main feature related to their brittleness, and plays an important role in affecting the complexity of fracture network in shale reservoirs. However, no brittleness index model based on fracture morphology has been developed so far. In the present research, a detailed analysis on morphological characteristics of shale fractures under triaxial compression

This paper presents a novel implicit method of characteristics (MOC) utilizing pressure-referenced characteristic line correction that ensures the efficiency and reliability of transient flow analyses for natural gas pipelines. The conventional implicit MOC utilizes an inertial multiplier that results in issues associated with numerical dispersion and convergence in fast transient flows. This increases

For underground gas storage projects that use depleted gas reservoirs, cyclic gas injection will change the stress fields and cause rock deformation. In-depth knowledge of the stress-induced deformation of reservoir rocks is important for secure gas storage. In this study, we performed a uniaxial compression computed tomography (CT) test with a reservoir sandstone sample to investigate the influence

Water-soluble polymers, as thickeners, are the vital component of high temperature-resistant fracturing fluids. With the expansion of oil and gas exploration and development to deep unconventional reservoirs, better performances for polymer-based fracturing fluids are required. According to the types of polymers, polymer-based fracturing fluids can be divided into biopolymers, synthetic polymers and

Flow of fracture containing proppant widely exists in the reservoir stimulation. In this article, a typical channel fracture containing large-size proppant is focused, where the average size of proppant is near the aperture of fracture. The propped fracture has the characters of large porosity and small wetted area. In view of the fact that the traditional permeability models cannot be applied to the