High-voltage electro pulse rock-breaking is a green breaking technology, which can achieve high efficiency of rock-breaking. It has a wide application prospect in deep and ultra-deep well drilling and tunnel driving in the future. Pursuant to the time delay characteristics of the gas discharge switch in the electro pulse boring (EPB) system, the equivalent model of the discharge circuit is established

Hydraulic fracturing techniques have been widely used to create complex fracture network in unconventional reservoirs. The complexity of hydraulic fracture is significantly influenced by pre-existing fractures that widely exist in reservoirs. A better understanding of the interaction mode between induced hydraulic fractures and pre-existing fractures is helpful to estimate the fracture complexity,

The frequency of occurrences per facility-year, their probabilities, and their uncertainties are critical inputs to hazard and risk management plans for underground storage facilities. We used Bayesian analysis to investigate and quantify the occurrence frequencies at US underground natural gas storage facilities in porous rock and salt-cavern storage facilities. Occurrences for each of the 31 hosting

The micro-occurrence and utilization patterns of coalbed methane and shale gas are complex, which has limited their scientific explorations and exploitation. Based on high-temperature/high-pressure nuclear magnetic resonance (NMR) online detection technology, a T2 cut-off calibration method for adsorbed, pore-confined and free gas was established. The “one-point calibration method” for the NMR T2 cut-off

The objective of this study is to reveal the implications of geological conditions on gas content and geochemistry of deep coalbed methane (CBM) reservoirs. It is of great practical significances to improve the theory and technology for deep CBM development. In this work, the gas content and geochemistry of selected samples were obtained by canister desorption method, gas chromatography (GC) and GC–Mass

The Cloisite 15A (C‒15A), an organically modified montmorillonite clay, was further modified with iron (Fe) pillars. Mixed matrix membranes (MMMs) were fabricated by incorporating Fe pillared Cloisite 15A (P‒C15A) at different loading percentage of 0.1 to 1.5 wt.% within the polysulfone (PSf) matrix. Fabricated membranes were characterized using thermal studies (TGA and DSC) and scanning electron microscopy

Nine as-received core samples were selected from four wells drilled in the Lacustrine Kongdian Formation, which is a source rock located in Cangdong Sag, Bohai Bay Basin, China, and their geochemistry and pore structure characteristics were investigated by Rock-Eval pyrolysis, low-pressure nitrogen physisorption (LNP), mercury intrusion porosimetry (MIP), and spontaneous imbibition (SI) tests. Various

It is important yet challenging to effectively and accurately predict the recovery of fractured reservoirs. Among numerous fractured reservoir simulation models, the embedded discrete fracture model (EDFM) is the most outstanding one for it incorporates the discrete fractures into structured grids of the matrix, which precisely describes the arbitrarily distributed fractures while not increasing the

Hydraulic fracturing treatment in rocks creates surfaces that are not smooth but rough in general. Accurate characterization of surface roughness is necessary to relate fracture deformation to fluid flow. In this study, we analyze the surface of an experimentally generated hydraulic fracture using a practical fractal approach which is capable of modeling applications. The hydraulic fracturing test

Cathodic protection (CP) method is widely used in the oil and gas industry in order to prevent (or reduce) rust and corrosion of structures and metal pipelines or their associated cost. To guarantee a more effective CP system, an applicable design for the under protected structures is required. The conventional models recommended by the designers are based on the equivalent circuit of the overall CP

A high content of CO2 in natural gas reduces its heating value and causes operational problems. Hence, it must be removed in a cost-effective way. In this paper, the metastability concept was used to investigate the non-equilibrium condensation of CO2 in a supersonic nozzle using ANSYS CFX and RGP tables generated based on data from GERG-2008 equation of state. Once the simulation was completed, the

The improvement of the normal operating mode in gas compression systems performs an essential role in enhancing the process of pumping and transporting the natural gas inside and outside the border of Algeria. In this regards, this paper introduces a novel output-feedback controller design with optimal static matrix gains K, which uses to control and maintain its internal stability by reducing the

Natural gas hydrate sampling technology is an important means to study in situ properties. Currently, there are certain limitations in the application of pressure preservation technology, such as poor sealing and low success rates. Hole-bottom freezing sampling technology has the advantages of a simple structure, large sample size, and high fidelity. To solve the problem of low freezing efficiency

Since the success of recovering natural gas from hydrate-bearing reservoirs (HBRs) in Shenhu Area of the northern South China Sea in 2017, China has successfully produced natural gas from hydrates in permafrost and ocean environments. It certainly will be required to achieve further research quality and scientific contribution for the natural gas hydrates exploitations in China. This paper is primarily

Complex tectonic settings are generally considered to be unfavorable for shale gas accumulation, but a favorable desorption-gas content has been detected in Lower Cambrian Lujiaping Shales in Dabashan fold-thrust belt in northeastern Chongqing, Southern China, which suggests a good exploration potential. High-pressure (~30 MPa) and high-temperature (~120 °C) (HP-HT) methane adsorption isotherms were

This paper investigated the suitability of xanthan gum as a thixotropic agent utilized in high-temperature natural gas well cementation. The konjac gum and KCl are used to synthesize a novel thixotropic agent and keep the thixotropic property of xanthan gum at high temperatures. The increment of consistency method are used to evaluate the thixotropic performance of the cement. Compressive strength

In order to ensure the safe operation of buried natural gas pipeline (BNGP) under landslide debris flow (LDF), a model is established to investigate the strain characteristic of BNGP. The influence of longitudinal LDF morphology is analyzed for the elliptic deformation rate, tensile and compression strain of BNGP. The results show that the influence area of LDF is about 5m from the upstream and downstream

Solid particles entrained in produced gas cause erosive damage in production and transportation facilities, that may eventually impact any process safety. The main purpose of this research is to determine the point on the Standalone screen (SAS) surface, where erosion rate is critical and to evaluate the uncertainties in the calculations and predictions of sand screen erosion utilizing CFD numerical

The tectonic fault poses a great threat to buried pipe segments. Buckling or rupture of pipes will ensue due to large strain induced by continuously increasing fault movements. In this study, a reliability-based methodology is conceptually proposed for designing new buried pipes or assessing existing pipes installed in fault areas. Uncertainties associated with the influencing factors of pipe structure

The accuracy control of the production pressure difference is of great importance to the efficient development of marine gas hydrates through depressurization. But from the field trial production, the existing control method of bottom hole pressure is difficult to achieve the expected depressurization target. To this end, a transient gas-liquid two-phase flow model in marine gas hydrate production

Thixotropy is the reversible breakdown of fluid microstructure when sheared. The microstructure achieves a new steady-state once shearing stops. Drilling fluids are thixotropic due to their rheological makeup which means that fluid microstructure has a time-dependent response to changes in applied shear rate. In contrast to the literature focusing on the time-independent nature of drilling fluid, few

Transient evaporation characteristics of water film in inorganic nanopores play an important role in the shale gas storage and transmission. Meanwhile, Inorganic nanopores in shale minerals exhibit complex geometric characteristics. In this work, TESCAN MAIA3 is used to observe the pore shape and size of inorganic nanopores. The pore shapes of rectangular or wedge-shaped are frequently occurred in

Gas kick is generally difficult to discover in time using traditional surface detection methods, which results in a significant wastage of time and money. Owing to the restriction of the low data-transmission speed of measurement-while-drilling system, downhole measured data is usually ignored in gas-kick detection. Furthermore, surface detection methods comprising the use of pressure and flow-rate

Oil and gas leakages represent the (functional) failure mode as a result of sealing failure of thread connections. With the expectation for more safer and efficient operations during the exploration and production phase of oil and gas fields, Oilfield Country Tubular Goods (OCTG) require the use of thread compounds (pipe dope) to lubricate tubular connections during installation, provision of high

Phase behavior of confined fluid demonstrates significant deviation from that of bulk fluid because of the strong molecule-wall interaction and geometric constraint in confined space, resulting in the inapplicability of the classical cubic equation of state (EOS). The objective of this work is to modify the Peng-Robinson EOS (PR EOS) with respect to both the attractive parameter and the covolume term

In view of the fatigue failure of tubing string caused by fluid-induced vibration (FIV) in high-yield curved well, a nonlinear vibration model of tubing string is established using energy method and Hamilton principle, which considers the longitudinal/lateral coupling effect of tubing string and the nonlinear contact collision effect of tubing-casing and verified by a similar experiment of tubing vibration

Automatic and early drilling risks detection is a significant issue of drilling cost reduction and drilling efficiency improvement. In this paper, considering the inherent nature of drilling process data, a novel drilling risks monitoring method which can automatically detect drilling risks in real time was developed. The newly proposed method integrated wellbore hydraulics model and streaming-data-driven

The behavior of chemical looping reforming of methane over the magnetite oxygen carrier (OC) has been investigated by thermodynamic analysis and experiments, which clarified the appropriate operating conditions and material composition. The possible revolution of the reaction composition and the corresponding isothermal redox reactions also have been carried out. Compared with the effect of temperature

Energy networks, especially the ones of natural gas, electric energy and district heating, are crucial infrastructures for the everyday life of our countries and cities. Thus, resilience and security of networks are becoming increasingly critical issues due to: a) the vulnerability of the territories, b) the effects of climate change (e.g. landslides, floods) and/or natural events (e.g. heartquakes)

China has become the second-largest producer of shale gas after the United States. This paper aims to explore other unique factors resulting in China's success by reviewing the history and experience of Chinese developers. The following findings were obtained. (1) The development of shale gas is less related to company size and is more related to a company’s goals and motivations. (2) Construction

Wellbore trajectory design is a nonlinear and constrained mathematical optimization problem that is used to build a cost-efficient, safe, and easily reachable trajectory. True measured depth (TMD), torque, and strain energy are used as objective functions to evaluate the wellbore trajectory design in this work. The minimum values of these objective functions enable a trajectory to be drilled with minimum

This paper provides a critical review of renewable and non-renewable synthetic natural gas production processes, technologies, and catalysts used to enhance the methanation processes. By completing this review, researchers have successfully provided a road-map for synthetic natural gas production research, as well as describing the current landscape for synthetic natural gas production, particularly

Over the past few decades, recurrent pipeline failures have caused a major impact on human lives and property damage. Studies have shown the lack of a comprehensive, integrated, and accessible set of risk-informed integrity management models and tools for pipeline operators are the main reason behind those damages. To address this gap, this paper presents a system-level Prognosis and Health Monitoring

Interest in gas hydrates has increased in recent years, both due to the high availability of fuel gases under hydrate form and the problems related to the formation of deposits in offshore pipelines during crude oil production. This paper aims to describe a new application of a real-time RGB image-analysis system to evaluate hydrate crystallization and to control the formation of deposits through the

Diversion of treatment fluid is the major attribute of successful refracturing treatment. This paper provides a comprehensive review of near wellbore and far-field diversion application and the selection parameters of chemical particulate diverters during refracturing treatment. Furthermore, this paper highlights laboratory tests for the performance evaluation and monitoring techniques during the treatments

In this work, a pragmatic technique has been developed to describe tracer flowback behaviour for a vertically fractured well in a tight formation by coupling fluid flow and geomechanical dynamics. More specifically, the Barton-Bandis model is employed to describe the relationship between effective stress and fracture permeability, while tracer flowback profiles, which can reveal the fracture properties

Defined as the backflow of a liquid film into a wellbore, liquid loading is a severe issue for gas wells because it decreases the production rate of gas. If the rate of liquid accumulation in the wellbore is extremely high, the production rate will significantly decrease, and, under extreme cases of accumulation, the operating company will abandon the well, leading to substantial financial losses.

Carbonate rock is a potential host for carbon dioxide storage. It is likely to react with carbonated water, following CO2 dissolution and dissociation in formation fluids. This might lead to carbonate dissolution or precipitation, depending on pH and formation fluid composition. In case of dissolution, the formation gets mechanically weaker, which could pose a risk for the mechanical stability of the

Supersonic swirl separation technology has been widely used in natural gas processing and has achieved good results. However, there are few studies on the application of supersonic separation technology to the removal of CO2 from natural gas, and the condensation rule of CO2 under supersonic swirling flow condition is still unclear. In order to study the supersonic swirling condensation characteristics

Optimizing hydrofracturing schemes for multiple vertical wells is crucial for developing complex fracture networks that facilitates the transport of unconventional hydrocarbon resources in tight reservoirs. The stress shadow effect that occurs between multiple wells has a significant effect on the development of fracture networks. However, the influence of fracturing schemes, including fracturing sequences

To elucidate the NMR response characteristics of gas-bearing shales, NMR T2 and T1–T2 experiments were performed on 38 shale samples selected from the Longmaxi Formation in the southern Sichuan Basin in China. The NMR signals of the totally dried shales were basically distributed in a single left peak and could not be removed completely. The T2 spectra of water-saturated shales presented two- or three-peak

Underground gas storage (UGS) is an industrial process used for compensating the supply and demand chain for natural gas in different seasons of the year. In this process, the excess natural gas produced in summer is injected into an underground reservoir to be harvested in winter. This porous medium also might contain an in situ gas which can be used as the cushion gas. The presence of a non-hydrocarbon

The effective stress principle plays an important role in the study of the permeability evolution and mechanical behavior of coal and rocks. A key to evaluating the effective stress is determining the evolution of the effective stress coefficient α. However, conventional triaxial stress-path tests are not suitable for reproducing the actual stress state of coal and rocks and thus determining the effective

The pressure transient technique has been widely used for laboratory tests on unconventional gas reservoirs; however, it is still a time-consuming process when applying this technique to rocks of ultra-low permeability in the nano-Darcy scale. The applicability of a novel radial-flow transient technique to achieve fast and accurate permeability measurements is verified by an experimental investigation

Artificial intelligence and machine learning (ML) are being applied to many oil and gas (O&G) applications and seen as novel techniques that may facilitate efficiency gains in exploration and production operations. Significant improvements in that regard are likely to occur when ML can be applied to evaluate O&G challenges with inherent synergies that may have otherwise not been evaluated concurrently

Small angle X-ray scattering (SAXS) has been widely employed to characterize the pore structure of coal and other geomaterials. However, in the many previous experimental investigations by SAXS, the probed samples were not standardized in terms of shape and particle size, even for the same geomaterial. The influence of pulverization on the pore structure of coal is generally ignored by the researchers

The molecular exchange is a frontline technology in the process of gas recovery from natural gas hydrate deposits. In such a case, the caged methane (CH4) molecules are exchanged with carbon dioxide (CO2). The process efficiency depends on several factors, including pressure (p) and temperature (T) of the injected gas. There are quite a few conflicting views on the guest-guest exchangeability; mainly

The fiber-optic distributed temperatrue sensor (DTS) has been used for flow profiling in horizontal multi-stage fractured wells, and several reservoir/wellbore coupled thermal models were developed. Although these theoretical models are applicable only to some specific scenarios, the industry has realized the great potential of DTS for production prediction in unconventional resources. This paper presents

To illustrate organic matter (OM) pores structure and evolution in shales with different maturities, the Triassic Yanchang shale (0.5% < Vitrinite reflectance (Ro) < 1.2%) in the Ordos Basin, the Lower Silurian Longmaxi shale (2.0% < Ro < 2.8%) and the Lower Cambrian Niutitang shale (3.0% < Ro < 4.2%) in the Yangtze Platform have been selected in this study. OM pores were analyzed by helium ion microscopy

A combination of thermal stimulation and CH4/CO2 replacement methods in the presence of nanoparticles was employed to enhance CH4 recovery and CO2 storage for a previously formed CH4 hydrate in a reactor. To this end, first, the effects of different CO2 injection pressures and CO2 hydrate formation temperatures were examined on the replacement process, and the optimum condition was obtained among the