Brittleness is a significant indicator of a series of engineering problems in the oil and gas community. However, the majority of brittleness evaluation methods focus on brittle rock, but few pay much attention to weak-brittle rock. In this study, an attempt has been made to study the relationship between released acoustic emission (AE) energy and brittleness during the fracture process of rock samples

The pulse-decay method is one of the most widely used transient methods for permeability measurements. Though many modified pulse-decay methods with various experimental designs have been proposed, the theoretical analysis is still insufficient, especially from the perspective of the boundary and initial conditions. In terms of boundary conditions, the tests can be conducted with a reservoir of finite

Hydrate formation has drawn wide-ranging research attention because of its applications in natural gas storage and transportation, refrigeration technology, seawater desalination, gas separation, capturing greenhouse gases, and energy storage. Also, THF hydrate has been widely investigated in terms of its kinetics, thermophysical properties, and suitability as a replacement for CH4 hydrates in experimental

In this study, a dynamic corrosion device for cement paste was developed according to the underground conditions of oil and natural gas wells, which possess a largely dynamic and constantly migrating corrosive medium. Using CO2 as the corrosion medium, the effects of the three corrosion conditions, namely static non-migration, dynamic non-migration, and dynamic migration of the corrosion solution,

Sectional hydraulic reaming technology has been widely used in China; however, because of the lack of research on mechanisms that reduce coal seam stress, improve air permeability, and promote methane extraction, on-site construction parameters are mostly determined from experience, and the effect is often not ideal. In this study, a stress-damage-flow coupling model for methane extraction was established

During hydraulic fracturing treatment, each wellbore section or interval does not receive equal treatment fluid because of non-uniformity in in-situ stresses. The application of chemical particulates for fluid diversion plays an important role in achieving a uniform distribution of treatment fluid in single or multistage hydraulic fracturing treatment. The diversion works on bridging and sealing mechanisms

As the demand for hydrocarbons increases, the search frontiers for petroleum and natural gas deposits keep being pushed towards unconventional terrains. An example of an unconventional terrain where oil and gas deposits can be found is the high temperature and high pressure (HTHP) environment. While HTHP wells can hold a wealth of resources, they are difficult and expensive to complete. One area of

Water soaking a horizontal shale well is a practice whereby operators in shale gas and oil production shut-in a well after a multistage hydraulic fracture treatment. By this practice, it is expected that production volumes will increase when the well is eventually opened to flow. However, there is currently no consensus on the benefits derived from this procedure. This is due to limited understanding

Measurements and monitoring of solids content and salinity in fluids to maintain these at ideal levels is essential for optimum well construction operations during drilling, completion, workover and abandonment phases. Currently, API measurements are used for solids and salinity determination, which have certain drawbacks and are difficult to automate. As an alternative, a novel in-line X-ray fluorescence

Natural gas transportation heavily relies on buried natural gas network. Unfortunately, natural gas pipeline leakage can cause environmental pollution and resource loss, and even leads to serious risks on human's life and properties due to its flammable and explosive properties. In this study, numerical stimulation methodology was applied to investigate the leakage and diffusion characteristics of

Hydrate technology is of considerable significance for industrial natural gas storage and transportation. In this paper, the hydrate formation in surfactants with different ratios of alkyl glycosides (APG) and sodium dodecyl sulfate (SDS) was studied at 275.15 K and 7 MPa. The results show that when the APG content was 20%, the gas storage density reached 117.44 mol/mol indicating the best hydrate

Gas hydrates have become a new focus in resource exploration and development. However, the sand production problem in the exploitation process of gas hydrate reservoirs greatly restricts the commercial-scale operation of hydrates. In this paper, by introducing a plastic softening stage, a thermal-fluid-solid coupled mathematical model for sand production based on the skeleton failure and phase change

Sulfur groups are very susceptible to adsorption onto coking coal. In this study, three major organic sulfides of coking coal were extracted and identified by experiments. Then, coal molecules containing sulfide groups were respectively constructed via simulation. The adsorption isotherm curves of methane under different moisture contents were created. The experimental results show that thiophanthren

Shale gas reservoirs, with typically ultra-low permeabilities, have been a major focus of hydrocarbon production over the past few decades. In this paper, we investigated how biogeomechanical alteration of near-wellbore properties could potentially impact hydrocarbon recovery from low-permeability reservoirs, using Wolfcamp shale and Niobrara shale formations. We first obtained the geomechanical properties

Vertical wells large scale fracturing and stimulated reservoir volume (SRV) treatments is an important method to enhance productivity of shale gas wells. Since the existence of micro-fractures in shale reservoirs, micro-fractures are opened and connect with hydraulic fracture after vertical wells large scale fracturing. Of course, some micro-fractures do not connect with hydraulic fracture, which leads

Currently, low-pressure gas (carbon dioxide and nitrogen) adsorption experiments have been widely applied to describe pore structure features of shales. However, there are no standard models in calculations of pore structure parameters from low-pressure gas adsorption experiments, which limits comparison between various studies. To evaluate the applicability of calculating methods, 9 Chang 7 shale

The key geological parameters controlling the enrichment and productivity of shale oil and gas (O&G) are studied systematically using 991 shale core analyses, and assay data from 72 systematic coring wells and 1317 rigs from the lower section of the Eagle Ford Formation in the Gulf Coast Basin of the United States. The key parameters include both source and derived parameters. Source parameters are

Most maintenance strategies serving for the practical applications are formulated based on the single maintenance objective and do not consider the physical layout of compressor units in the complex pipeline networks and the actual maintenance demands, resulting in the over-maintenance or under-maintenance. The effective maintenance strategies for compressor units improve the unit reliability, economy

In this paper, a new assisted history-matching workflow is presented, where rate transient analysis (RTA) results are used to constrain not only the initial discrete fracture network (DFN) models, the interpreted flow regimes are also used to formulate a localization scheme for more efficient updating of the pertinent DFN model parameters. The outcome is an ensemble of DFN realizations that are calibrated

Pore fluids are generally classified into movable fluid and irreducible fluid by one or two NMR T2 cut-offs (T2C). Fluid movability in tight sands may not be accurately characterized by pore size-based classification methods solely because of the complex pore structure and heterogeneity in pore size. In this study, we propose a nine-grid model to characterize fluid movability and calculate the percentages

Hydrates are easily formed at low-lying parts of high-sulfur gas-liquid mixed pipelines due to liquid accumulation. In pigging operations, the pig is often jammed. In order to avoid pig jamming, a novel foam jetting pig was designed in this study. The kinetic model of the jetting pig was established to simulate the hydrate crushing process. In addition, the foam jet flow experimental system was constructed

Synergetic effects of matrix components and diagenetic processes on pore properties were investigated from macroscale to nanoscale. Methods were combined to explore shales selected from well J1 in South China, in terms of elements measurement, organic geochemistry analysis, X-ray diffraction, nuclear magnetic resonance and direct imaging observation (2D wide horizon and 3D reconstruction). Three lithofacies

Microwave heating fracturing is potentially a green stimulation technology for gas shale recovery. However, the mechanism together with permeability evolution of microwave irradiated reservoir remain unclear. To fill this knowledge gap, the responses of Longmaxi shale from the Sichuan Basin, southwest China, to both continuous and intermittent microwave stimulation along variable microwave heating

Hydraulic fracturing has been proved to be an effective way to unlock shale gas resources. During this process, fracturing fluid comes into contact with shale reservoirs and interact with the rocks. This could cause alteration of the pore systems in shales, thereby affecting gas transport and production. To illustrate this geochemical process and identify the physical and chemical alterations of shales

The coal measure strata of the late Paleozoic Taiyuan Formation in northern China, which are mainly composed of coal, mudstone, limestone, and sandstone, with obvious cyclothems, are important with respect to the development of unconventional natural gas. However, the organic matter provenance and enrichment mechanism in transitional facies are still controversial. In this study, the organic geochemistry

This paper introduces a gravity regional interpretation workflow for mapping the natural fracture system, a challenge in unconventional reservoir exploration. The workflow comprises coupling two gravity data attributes, the tilt angle and the multiscale edge detection (worming), to build a high-resolution image structural framework of a given basin’s basement. That includes a description of the fault

Methane has enormous potential as a carrier for renewable H2. The required infrastructure for a methane gas economy is readily available, and it can compete with its energy-intensive liquefied hydrogen (LH2) counterpart. In this work, we conducted a technoeconomic analysis of the production of liquefied synthetic methane (LSM) from ambient CO2 and renewable H2. The process entails (1) capture of CO2

In the process of shale coring, the drilling fluid and its solid-phase immersion inevitably cause core pollution, thereby increasing the flow resistance of the gas inside the core and leading to inaccurate calculations of the loss of shale gas. To study the changes in the seepage resistance and the amount of gas lost while the shale is immersed in the drilling fluid, an experimental study on the effects

Inaccurate predictions of the vapour-liquid equilibria of polar gas hydrate formers and organic inhibitors can lead to erroneous hydrate phase equilibrium predictions for these associating components. In this work, parameters of the cubic plus association equation of state (CPA-EoS) were optimized for associating components by simultaneous minimization of absolute errors of saturated liquid densities

Maintaining the optimum viscosity of foam required to create the effective fracture permeability and placing the proppant inside the fracture are difficult because of its poor thermal stability. The objective of this study is to optimize the viscosity of foam by using the Response Surface Methodology (RSM) technique. The Box-Behnken design matrix was selected based on the feasibility, efficiency and

Due to the ever-increasing energy demand, the study of gas production from marine methane hydrate attracts intensive interest around the world. Vertical wells were adopted in most of the previous production tests, although horizontal well might be with significant advantage over vertical well in production performance. To evaluate the gas production performance from a high irreducible water saturated

Regarded as two of the most challenging flow assurance issues during the production of oil and gas in offshore fields or ultra-deep seas, wax and hydrates may coexist in multiphase pipelines, greatly jeopardizing the safety of operation and transportation. Understanding the coupling rheological properties of the coexistence system is vital to guarantee the transportability of pipelines. In this work

The processes of shale gas transport and enrichment are closely related to the micro-fractures structure. Here, porosity, permeability test, gas adsorption, scanning electron microscopy (SEM), fluid spontaneous imbibition, Nano-CT, Micro-CT, and core observations were used to determine the types and characteristics of micro-fractures in the Longmaxi shales, Jiaoshiba area. The effects of micro-fractures

Produced water (PW) of the liquid phase is the largest volume by-product from the process of offshore oil and gas production, and compact and efficient treatment methods are brought into focus. The PW, condensate oil, and floccule in the liquid phase all require treatment to satisfy the requirements of the standards. The liquid phase volume from offshore gas fields is typically not as large as that

Experiments were carried out to find out the effect of different TFGR ratios on flame characteristics, pollutant emission, temperature, luminosity, IR radiation and total radiation of natural gas flames. A spiral duct connected tangentially to the furnace inlet linked the furnace to the chimney. A centrifugal fan was installed on the spiral duct to suck the combustion products and a spiral duct back-draft

Transportation of Carbon Dioxide (CO2) is an essential part of Carbon Capture and Storage (CCS) chain. Transportation using pipelines is known as one of the most economical ways for large-quantity of CO2. In CCS projects, it is very important to ensure the safe operation of the CO2 pipelines. Thus in the design stage, the risk associated with CO2 pipelines should be identified. This paper reports a

Pipelines are mainly used to transport crude and refined petroleum, such as natural gas, worldwide. Monitoring pipeline health condition at offshore locations is challenging. Despite several attempts to develop leak detection systems, few can simultaneously detect the leak location and size. It is extremely difficult to obtain abnormal data such as actual leaks from a long-distance subsea pipeline

One of the difficulties in the simulation of ductile crack propagation in the gas pipeline is the implementation of complex loading. It is difficult for traditional loading methods to accurately predict the real-time crack tip position and then update the boundary conditions accordingly, which makes the simulation results inaccurate. To solve this problem, an iterative loading method considering the

Anisotropic Rock Physics Templates (RPTs) are efficient tools to interpret well logs. In this work, micromechanical modeling is used to calculate the effective properties of heterogeneous and anisotropic rocks due to the presence of fluid-filled aligned fractures or other minerals, e.g. clay, quartz and calcite. When the spheroidal inclusions are aligned, the transversely isotropic symmetry is described

Complex interactions between hydraulic fractures and natural fractures often result in highly complex fracture networks that might lead to bypassed resources damaging the economic viability of developments. In this study the impact of natural fractures of the formation on production from hydraulically fractured wells is studied using a recently developed fracture upscaling method (FUM). By capturing

Injection of carbon dioxide (CO2) into coal seam gas reservoirs has been considered one of the most popular approaches to enhance methane (CH4) production. However, many geological and engineering factors influence the efficiency of CH4 displacement by CO2. These factors include depth-induced changes in pressure and temperature, accompanied by gas compounds, moisture content, and salinity of the underground

Gas relative permeability characterization is of key significance to model the behavior of gas flow in gas hydrate-bearing sediments. The present study proposes a novel model to relate gas relative permeability to gas hydrate saturation based on X-ray micro-CT imaging information of xenon hydrate pore-scale distribution in sand sediments. Lattice Boltzmann method (LBM) was used to obtain permeability

Production performance analysis of shale gas based on dynamic parameters is now playing a more important role as a scientific basis for gas well development plan, and describes the structural features, evolution and predict the future production trends. Owing to multi-gradient of gas demand and high fluctuation of the yield adjustment period, it is difficult to identify whether the change of production

Fast and accurate characterization of unconventional gas reservoirs is of great significance for estimation of gas-in-place and enhancement of gas recovery; however, it remains a big challenge to efficiently and effectively determine the permeability of tight-structure reservoirs in the nano-Darcy scale, especially for those reservoirs with strong gas sorption potential. A novel pressure transient

A common approach to reduce the Euler equations’ complexity for the simulation and optimization of gas networks is to neglect small terms that contribute little to the overall equations. An example is the inertia term of the momentum equation, which is said to be of negligible size under real-world operating conditions. However, this justification has always only been based on experience or single

Microwave irradiation (MI) is a new method to enhance desorption of shale gas. It is very important to explore the desorption law and influencing factors of shale samples under MI to improve energy utilization efficiency and optimize microwave stimulation effect. The gas desorption properties of shale sample under different MI time (off-line group) and power (on-line group) conditions were discussed

The efficiency of a hydraulic fracturing treatment is directly related to the total surface area of the fractured formation. Development of design guidelines for selecting the optimal perforation cluster spacing, fracturing fluid type, rheology, and flowrate can help maximize well production following a hydraulic fracturing treatment for an arbitrary in-situ stress state, formation type, and other

Permeability prediction of submarine shallow sediments is significantly important for finding hydrate-bearing sands with commercial potential. Permeability could be more sensitive to hydrate occurrence than traditional velocity parameters, because the rapid decrease of permeability is probably caused by hydrates. The elastic characteristics of the hydrate-bearing sediments differ from the consolidated