Natural Gas Development Research Articles

Inequity of Exposure to Unconventional Natural Gas Development in Northeastern British Columbia, Canada─An Environmental Justice Analysis.

In the past two decades, northeastern British Columbia, Canada, has experienced rapid growth in unconventional natural gas production and is home to Indigenous and rural communities. Living near oil and gas production can lead to deteriorated air quality that negatively impacts human health. This study explores whether three oil- and gas-related exposure metrics: modeled concentrations of 12 gases and particles; oil and gas facility-reported emissions; and active wells are disproportionately distributed in areas with higher concentrations of Indigenous people and community socioeconomic vulnerability. We calculated exposure metrics from 2018 to 2020 in geographic dissemination areas (DAs). We used a rural deprivation index that included income, education, employment, and access to amenities to identify areas of high socioeconomic vulnerability. We estimated that DAs with greater than 90% Indigenous population experience 1.2-1.8 times higher median air pollution concentrations than DAs with less than 10% Indigenous population. We estimated that DAs with high community vulnerability experience higher modeled air pollution and higher odds of exposure to facility emissions, with the most vulnerable areas experiencing 11-96 times higher median air pollution concentrations. Overall, these results suggest the presence of environmental injustice in an area that is expected to continue producing a large portion of Canadian natural gas.

Gas-bearing prediction of tight clastic rock reservoirs based on random forest-modern temporal convolutional network

Reservoir gas-bearing identification is a crucial link in natural gas exploration and development. However, under the conditions of sparse well distribution, challenges such as insufficient prior information and low identification accuracy often arise. In response, we have developed a method for identifying the gas-bearing of tight clastic reservoirs based on the fusion of well logging and seismic data. Initially, feature engineering processing is applied to P-wave slowness, S-wave slowness, and density to calculate petrophysical parameters and fluid indicators, using the random forest algorithm to refine reservoir-sensitive parameters. Subsequently, a deep-learning network named modern temporal convolutional network (ModernTCN) is constructed, which uses reservoir-sensitive parameters as inputs for model training and testing. This network features a decoupled design to segregate temporal and feature information, effectively capturing the longitudinal gas-bearing characteristics of the reservoir. Next, we compare the ModernTCN with a fully convolutional network, a multiscale fully convolutional network, a self-attention bidirectional long short-term memory network, a self-attention bidirectional gated recurrent unit, and a 1D deep residual network to determine the reliability of this method. Furthermore, a probabilistic weighted voting algorithm based on the multi to single strategy captures the spatial correlation among adjacent seismic traces to predict lateral distribution characteristics of the reservoir. Ultimately, the methodology is applied using seismic and well data from the Huangyan structural belt of Xihu Sag, China, to identify gas-bearing zones in tight clastic rock reservoirs. The results are validated through the reflection characteristics of the test well logs and along-horizon slicing. This approach determines substantial well-seismic concordance, confirming its potential to support the exploration and development of tight clastic gas reservoirs.

Inverse numerical model for isothermal adsorption experiment and its application in gas diffusion kinetics

Diffusion plays a crucial role in the mass transfer and migration of coalbed methane within coal-rocks. The diffusion coefficient is a key parameter that influences the diffusion of CH4 in porous media, including coal-rock. Conventional experimental approaches, reliant on theoretical solutions for diffusion coefficient determination, exhibit inherent limitations including theoretical constraints, protracted experimental procedures, and susceptibility to errors. Addressing these shortcomings, this study introduces a numerical method based on inverse problem calculation, the core of this method lies in an optimization process that adjusts model parameters by minimizing the error between observed data and model predictions, ensuring that the model output closely matches the actual observed values. Building on the traditional isothermal adsorption experiment for CH4, we use isothermal adsorption pressure fluctuation data as a penalty factor, inverse problem numerical optimization techniques are employed to determine the coal particle diffusion coefficient. The results indicate that during the initial adsorption stage, CH4 molecules rapidly penetrate into coal particles, followed by a diffusion and adsorption process. The flow sequence of CH4 over different time periods adheres to a sequential transport mode of “free flow, permeation, diffusion, adsorption.” Using this model, we determined the diffusion coefficient of coal particles to be 1.295 × 10−13 m2/s through reverse optimization. The fitting accuracy (R2) with experimental data was 0.973, which indicates the reliability of the results. This new method effectively determines the diffusion coefficient of gases in coal samples and offers valuable guidance for the development and utilization of unconventional natural gas.

Study on the safety distance determination model for natural gas wells in Ordos Basin subsidence areas of coal mining

To optimize the safe distance between coal mining faces and natural gas wells, with the Ordos Basin as the engineering background for the intersectional development of natural gas and coal resources, a Gaussian function equation for subsidence curves under complete mining was proposed based on the probability integral method, and a model was constructed to determine the coordinated mining safety distance between coal mining faces and natural gas wells. Based on the distributed optical fiber monitoring principle of the BOTDR technology, on-site monitoring of the simulated monitoring well GX1 within the safety distance was carried out. The results indicated that the maximum strain change values of the outer casing and inner production casing of the simulated monitoring well GX1 were 836 με and 766 με, respectively, far less than the maximum ultimate tensile strain value of the overlying rock at the same depth position. Furthermore, the casing structure possessed ample resistance capability, ensuring no noticeable deformation occurred. Through comparison, it was found that the discriminant model reduced the reserved safety distance between the coal mining working face and the natural gas well by 58% compared with the currently used avoidance method of the surface subsidence boundary, liberated coal resources, and achieved a "win–win" situation of the coordinated mining of natural gas resources and coal resources. It can reasonably adjust the coordinated mining problem without a natural gas-coal co-mining mechanism, provide a new method for the layout of natural gas wells in gas-coal overlapping areas, and provide new ideas for the coordinated mining of coal-related associated resources.

Cumulative Exposure to Unconventional Natural Gas Development and the Risk of Childhood Cancer: A Registry-Based Case-Control Study.

The rapid growth of unconventional natural gas development (UNGD), also known as hydraulic fracturing, has raised concerns of potential exposures to hazardous chemicals. Few studies have examined the risk of childhood cancer from exposure to UNGD. A case-control study included 498 children diagnosed with leukemia, lymphoma, central nervous system neoplasms, and malignant bone tumors during the period 2010-2019 identified through the Pennsylvania Cancer Registry. Cases were matched to controls using Pennsylvania birth records. For each subject, a new overall UNGD exposure metric was calculated which incorporates both spatial (proximity) and temporal (duration) aspects of well activity. Conditional logistic regression models were used to estimate the risk of combined and individual cancers by overall UNGD exposure, and well proximity. Children with a higher overall UNGD exposure (3rd/4th quartiles) had an increased risk for the four malignancies combined [OR] 1.69 (95% CI 1.01, 2.82) and 1.79 (95% CI 1.00, 3.19) compared to non-exposed children. Overall, individuals living within 0.5 miles of a UNGD site were 3.94 times (95% CI 1.66, 9.30) more likely to develop a malignancy compared to non-exposed children and the risk of lymphoma within 0.5 miles and 0.5-1 miles was also elevated [ORs of 5.05 (95% CI 1.09, 23.39) and 7.71 (95% CI 1.01, 59.00), respectively] compared to non-exposed. Our study found that overall UNGD cumulative activity as well as a proximity to UNGD wells were associated with an increased risk of childhood lymphoma and overall childhood cancers combined.

Optimizing Final Investment Decision with Real Options Valuation: A Case Study of Offshore Natural Gas Development Project in Indonesia

Optimizing Final Investment Decision with Real Options Valuation: A Case Study of Offshore Natural Gas Development Project in Indonesia

Predicting the depth of rock cutting by abrasive water jet using support vector machine optimized with whale optimization algorithm

The utilization of abrasive water jet (AWJ) has garnered notable attention in subsurface engineering, as well as unconventional natural gas development, geothermal energy extraction, and tunnel excavation. The efficiency of construction operations is contingent upon rock fragmentation, which is controlled by AWJ parameters and rock properties. Currently, the parameter settings for rock fragmentation by AWJ predominantly rely on empirical approaches, and existing prediction models have large errors due to a limited number of training samples. In this study, we propose a combined support vector machine (SVM) and whale optimization algorithm (WOA) model. To test the model's predictive performance for rock-breaking depth, a database consisting of eight input parameters is constructed. These parameters include AWJ pressure, target distance, lateral velocity, abrasive types, mass flow rate, abrasive particle size, rock types, and rock uniaxial compressive strength. Additionally, to demonstrate the superiority of the WOA-SVM model, three other predictive models based on the back propagation (BP) network, SVM, and Random Forest (RF) are established, compared, and evaluated. The results show that the optimized WOA-SVM model is the most accurate in predicting rock cutting depth, achieving a precision rate of 0.972 25 compared to other models (BP: 0.9536; RF: 0.9681; SVM: 0.9687). Furthermore, sensitivity analysis highlights that lateral velocity exhibits the highest impact on the model, followed by jet pressure and the uniaxial compressive strength of rock. This underscores the critical importance of prioritizing the adjustment of lateral velocity, AWJ pressure, and rock properties when engaging in rock-cutting operations.

Comprehensive Analysis of the Annulus Pressure Buildup in Wells with Sustained Gas Leakage Below the Liquid Level

During the process of natural gas development, sustained casing pressure (SCP) frequently occurs within the annulus of the gas wells; we specifically referred to the “A” annular space located between the tubing and the production casing in this paper. SCP in an annulus poses a paramount safety challenge, universally acknowledged as a significant threat to gas field development and production, jeopardizing well integrity, personnel safety, and environmental protection. There are multiple factors that contribute to this issue. Due to the multitude of factors contributing to SCP in an annulus and the unclear mechanisms underlying the pressure buildup in wells, an early assessment of downhole leakage risks remains challenging. Hence, this study focused on a comprehensive analysis of the SCP in the annulus of gas wells. A detailed experimental study on the pressure buildup in an annulus due to tubing leakage below the liquid level was conducted, and the variation patterns of the annulus pressure under various leakage conditions were explored. The findings indicated that the equilibrium attainment time of annulus pressure at the wellhead subsequent to tubing leakage decreases with the increase in the pressure difference between the tubing and the casing, the liquid level height, the leakage orifice diameter, and the quantity, while it increases with the increase in the leakage position and gas temperature. According to the theory of gas fluid dynamics, a predictive model of the annulus pressure buildup with sustained gas leakage below the liquid level was proposed, which was well-validated against experimental results, achieving a model accuracy of over 95%. This study provided a theoretical framework for diagnosing SCP in the annulus of gas wells and developing mitigation strategies, thereby contributing to the advancement of the research field and ensuring the safety of industrial operations.

Analysis of the Impact of Clusters on Productivity of Multi-Fracturing Horizontal Well in Shale Gas

Shale gas reservoirs with nanoporous media have become one of the primary resources for natural gas development. The nanopore diameters of shale reservoirs range from 5 to 200 nm, with permeability ranging from 1 × 10−9 to 1 × 10−6 μm2. The natural gas production from shale gas reservoirs is low, necessitating the use of multi-stage hydraulic fracturing in horizontal wells. Segmented multi-cluster perforation fracturing is an effective method for shale gas extraction in these wells. The number of clusters significantly impacts the productivity of horizontal wells. Therefore, it is essential to analyze the impact of cluster numbers on fracture productivity in shale gas reservoir development. In this study, the equivalent flow resistance method was applied to establish a productivity model for multi-stage hydraulic fracturing horizontal wells in shale gas reservoirs considering diffusion and slip. An approximate analytical solution was obtained, and the effects of cluster length, diffusion coefficient, and fracture network permeability on productivity were analyzed. The results show that gas production gradually increases with the increase in the number of clusters and cluster length. However, as the number of clusters increases, the interference between clusters leads to a decrease in the productivity of individual clusters. As the fracture permeability, fracture network permeability, and diffusion coefficient increase, shale gas production also gradually increases. The permeability of the fracture network has the greatest impact on productivity. These research results are beneficial for the design of clusters in horizontal well fracturing and are of great importance for the development and production of shale gas reservoirs.

Uncertainty prediction of conventional gas production in Sichuan Basin under multi factor control

The establishment of a natural gas production model under multi factor control provides support for the formulation of planning schemes and exploration deployment decisions, and is of great significance for the rapid development of natural gas. Especially the growth rate and decline rate of production can be regulated in the planning process to increase natural gas production. The exploration and development of conventional gas in the Sichuan Basin has a long history. Firstly, based on the development of conventional gas production, the influencing factors of production are determined and a production model under multi factor control is established. Then, single factor analysis and sensitivity analysis are conducted, and multi factor analysis is conducted based on Bayesian networks. Finally, combining the multivariate Gaussian mixture model and production sensitivity analysis, a production planning model is established to predict production uncertainty under the influence of multiple factors. The results show that: 1) the production is positively correlated with the five influencing factors, and the degree of influence is in descending order: recovery rate, proven rate, growth rate, decline rate, and recovery degree. After being influenced by multiple factors, the fluctuation range of production increases and the probability of realization decreases. 2) The growth rate controls the amplitude of the growth stage, the exploration rate and recovery rate control the amplitude of the stable production stage, the recovery degree controls the amplitude of the transition from the stable production stage to the decreasing stage, and the decreasing rate controls the amplitude of the decreasing stage. 3)The article innovatively combines multiple research methods to further obtain the probability of achieving production under the influence of multiple factors, providing a reference for the formulation of production planning goals.

Experimental Study on the Optimal Operating Envelops of Ejection Supercharging Technology for Unconventional Natural Gas

Abstract Ejection supercharging technology could make use of the energy of high pressure gas wells to assist the development of low pressure unconventional natural gas. But at present, the process of adaptability analysis is complicated, the period is long, and the process implementation is difficult in process application. In this paper, based on the production situation of unconventional natural gas, experiments are carried out to investigate the impact of structural and operational parameters on the performance of ejection supercharging. According to analyze the relationship among high, middle and low pressure inlet conditions and their influence on operational performance, as well as the dimensionless processing of pressure parameters, the optimal operating envelops of Ejection supercharging technology for unconventional natural gas is established. Furthermore, A chart is proposed with variable parameters under different conditions to determine the target gas wells for this technology, allowing for a rapid analysis and determination of whether gas wells are suitable for Ejection supercharging technology. And it also get the pressure reduction range of the process acting on the low pressure well, which provides a reference for analyzing the application effect of the process. Finally, The results of the case analysis demonstrate a 100% match rate with the chart established in this paper. The research results greatly simplify the process of well selection, and transform the analysis for specific working conditions one by one into a unified analysis for multiple working conditions, consequently lays a solid foundation for the widespread application of the ejection supercharging technology for unconventional natural gas.

Research and Application of Plugging Drilling and Completion Technology for Difficult Old Well in Changchun Gas Storage

Abstract Changchun Gas Storage has been included in the 14th Five-Year Plan for the development of petroleum and natural gas in Jilin Province. Its smooth construction and safe operation are crucial to ensure the stable supply of natural gas in Changchun. Well X106F located in the construction area was abandoned in 1988 due to drilling tool falling and multiple salvage failures. In order to ensure the sealing and integrity of the gas storage, it is necessary to effectively plug the drilling cover. In view of the problems of low well history accuracy, poor well wall stability and difficulty in cementing large boreholes, open hole drilling, trajectory design and control, film-forming and wall-fixing drilling fluid and prestressed cementing technologies are applied. By optimizing drilling tools, optimizing drilling parameters, designing the three-opening well structure and “five-section” profile, the plugging well construction requirements are met. The first and second open drilling along the old well borehole, 1313m deep on the first try to find top of the fish, after cementing plug, side tracking to 50m below the top of the fish and then cementing;for third spud control trajectory to accompanied the old well, according to the results of passive magnetic guidance, real-time adjustment of the trajectory scheme and construction plan, finally successfully collided with the old well at 1893m deep, after cementing the drilling plug, perforating and extruding cement, the cement job quality is good. The whole well construction period of 100 days, creating the fastest record of the old well plugging without trajectory of the fish type, providing technical support for the construction of Changchun gas storage, and providing experience for the same type of old well plugging and complex well treatment in China.

Multi-Parameter Experimental Investigation on the Characteristics of Acidizing Effectiveness in High-Temperature Carbonate Formation

Carbonate formation is the key reservoir in Sichuan Basin for natural gas development. Compared with the early stage of development, the burial depth of targeted formation becomes deeper, and the formation temperature gets higher. So, the characteristics of acidizing effectiveness in high-temperature carbonate formations make this evaluation slightly difficult. Currently, it is common that a single parameter is considered to study acidizing effectiveness by simulation and experiment methods. In this paper, for a more accurate investigation of acidizing effectiveness, multiple parameters, including permeability change rate, fracture conductivity, and surface roughness, were introduced by a series of experiments. It is revealed that the permeability change rate is more than 57% when using gelled acid. As the amount of diverting agent increases in diverting acid, the viscosity of the acid grows to its peak with the reaction, making it easier to block the high permeability core temporarily and divert to acidify the low permeability core, where the permeability change rate of the low permeability core goes from 51.6% to 64.2%, which shows well acidizing effectiveness. In addition, the short-term and long-term conductivity of the samples from the three different formations are more than 200 mD∙m under high closure stress. The conductivity of Maokou Formation is the largest due to its high content of carbonate minerals and high dissolution rate. And the results of long-term conductivity are consistent with those of surface roughness, making the evaluation results more reliable for acidizing effectiveness. It is worth noting that temperature is a factor that cannot be ignored in the evaluation of acidizing effectiveness because it has a great influence on the performance of the acid system, such as viscosity and the reaction-reduced rate, leading to an acidizing effectiveness affect. So, the temperature resistance of an acid system is important as well.

Gas Reservoir Identification Based on Nonstationary and Anisotropic FFT-MA Stochastic Modeling

Summary High-resolution reservoir modeling is a crucial technique for the precise identification of gas reservoirs, holding significant importance in guiding natural gas development. However, the nonstationarity and statistical anisotropy of subsurface media present immense challenges to the reliable implementation of high-resolution reservoir modeling. In response to the nonstationarity and anisotropy of complex reservoirs, we propose a novel stochastic modeling method based on fast Fourier transform moving average (FFT-MA). In this method, variational mode decomposition (VMD) is introduced to decompose logging curves into a series of sparse components with specific center frequencies and narrow bandwidths. Subsequently, the autocorrelation functions of each component are computed and synthesized, thereby inferring the nonstationary vertical autocorrelation functions of logging curves. In addition, to characterize the anisotropic and lateral nonstationary features of the reservoir, angle parameters and lateral autocorrelation functions are extracted from seismic records. Lastly, considering the high sensitivity of Lamé constants (λ and μ) and their density-combined counterparts (λρ and μρ) to gas-bearing reservoirs, FFT-MA stochastic modeling is applied to λρ, μρ, and ρ. Gas identification is then performed based on the joint probability distribution extracted from logging data. The proposed method is tested in the sand-shale reservoirs of the Yinggehai Basin, China. The results indicate that the stochastic models for λρ, μρ, and ρ effectively characterize the nonstationary and anisotropic features of complex reservoirs, significantly enhancing the resolution and accuracy of gas identification.

Interfacial properties of CO2 and liquid sulfur in high-sulfur gas fields: Molecular simulations on carbonate mineral surfaces

Interfacial properties of CO2 and liquid sulfur in high-sulfur gas fields: Molecular simulations on carbonate mineral surfaces

Performance evaluation and physical simulation experiment of SiO2 nanoparticle synergistic crosslinked polymer system

Abstract As natural gas development gradually shifts from early to mid to late stages, water outflow from gas wells has become an inevitable problem. In this study, polyethyleneimine cross-linked polymers were synthesized and nano particles were introduced to obtain SiO2 nanoparticle synergistic cross-linked polymer systems. Rheological experiments show that the system has stronger shear resistance and higher yield stress, and the linear viscoelastic region has a stress amplitude less than 3.5Pa, exhibiting good elastic properties in the range of 0.01 to 10Hz. In terms of stability, after 45 days of aging, the viscosity retention rate of the system is 77.66%. When the mineralization degree is 224852mg/L, the viscosity retention rate is greater than 76.33%, indicating that the system has good aging stability and salt resistance.The physical simulation experiment of core displacement shows that SiO2 nanoparticle synergistic cross-linked polymer gel has gas-water selective plugging ability, and the reduction of water phase permeability is much greater than that of gas phase. The gas phase permeability can remains at about 75%, which is 2300 times that of water phase permeability, and has a good water plugging effect.

Characteristics and Control Factors of a High-Quality Deeply Buried Calcareous Sandstone Reservoir, the Fourth Member of the Upper Xujiahe Formation in the Western Sichuan Basin, China

A special type of sandstone in which carbonate rock fragments (CRFs) dominate the composition developed in the Upper Triassic Xujiahe Formation’s fourth member (Xu4) in the western Sichuan Basin, known as calcareous sandstone. Calcareous sandstones are widely distributed in the western Sichuan and is the main production target of tight sandstone gas in the Sichuan Basin. In this study, thin sections, porosity–permeability testing, scanning electron microscopy, and X-ray diffraction are applied to examine the characteristics and control factors for high-quality reservoirs in the calcareous sandstones, with a view to providing guidance for natural gas exploration and development in calcareous sandstones. The results show that the calcareous sandstone belongs to litharenite, with an average framework grain composition of 30% quartz, 1% feldspar, and 69% rock fragments, while the Xu4 sandstone has a high quartz content (average content of 71%). Primary intergranular pores are the main storage space, and the reservoir quality is quite poor. Under the influence of different parent rock properties of sandstones, there are obvious differences in the composition of framework grains between the calcareous sandstone and the ordinary Xu4 sandstone, which in turn affects the reservoir storage space, diagenesis, and reservoir quality. High-energy depositional conditions, low content of late cements, and the development of fractures are the main controlling factors for the formation of high-quality reservoirs in Xu 4 calcareous sandstones.

Fractured perceptions: Unconventional oil and gas development and the social construction of perceptions of risk in South Africa

Fractured perceptions: Unconventional oil and gas development and the social construction of perceptions of risk in South Africa

Research Progress and Suggestions on Natural Gas Industry Technology Revolution in the Context of Energy Revolution

The energy revolution is an important driving force for the progress of productivity and civilization in human society. As a big country in global energy consumption and carbon emission, promoting the energy revolution is a strategic choice to ensure the sustainable development of China's energy industry, which is in line with China's national conditions of the construction of modern energy system. Based on the strategic background of the energy revolution, this paper combines China's natural gas production capacity and consumption demand in the context of national conditions, and from the perspective of technological revolution, we have sorted out the research results of relevant scholars on the natural gas industry and the technological development of the whole industry chain of “production, supply, storage and marketing”, and discussed the technological development of China's natural gas industry in the context of the energy revolution. The results of the study show that: (1) the innovative technology of natural gas industry is diversified, low-carbon and green development, but from the dimension of safety, stability and economy, the performance is relatively weak. (2) The overall synergistic development of the whole industrial chain technology is uneven, the gap between supply and demand is increasing, and the degree of information and intelligence is low. And then for the development of China's natural gas industry technology puts forward proposals: (1) to promote innovative natural gas technology breakthroughs, integration of new areas of technology, to achieve the dual objectives of low-carbon economic development and environmental protection; (2) to increase natural gas exploration and development efforts, breakthroughs in the integration of the digital transformation of traditional exploration technology, and continue to support the increase in storage and production; (3) to accelerate the upgrading of natural gas supply and demand, and the establishment of a synergistic, intelligent, diversified pipeline network system. (4) Boost the construction of gas storage system, pay attention to the standardized gas storage management system, and play the role of valley cutting and peak leveling; (5) Build a new comprehensive energy service system, and build a multi-species, multi-link intelligent technology integration to create a new service system.

Progress, Challenges, and Strategies for China’s Natural Gas Industry Under Carbon-Neutrality Goals

In recent years, the Chinese government has introduced a series of energy-saving, emission-reducing, and environmentally protective policies. These policies have gradually decreased the proportion of high carbon-emitting energy consumption, such as coal, in China’s energy structure. The proportion of natural gas consumption as a clean energy source has been increasing year by year. In the future, with the deepening decarbonization of the energy structure, the applied scope of natural gas utilization will expand, increasing demand. Therefore, this study first evaluated the development of China’s natural gas industry from the perspectives of development evolution, technological applications, and industry achievements. Secondly, based on the current situation of conventional and unconventional natural gas development, both resources and technological potential were analyzed. By taking several typical projects in the natural gas industry as examples, medium- and long-term prospects for natural gas development were planned and predicted. Building on this analysis, we employed the SWOT method to examine the development prospects of China’s natural gas industry and propose development goals. Finally, based on top-level design considerations and previous research analysis, suggestions and measures were proposed for technology implementation, regional layout, industrial chain collaboration, and support policies. These recommendations aim to provide planning support and management references for the development of China’s natural gas industry.