Gas Field Research Articles

Weight Assignment Method and Application of Key Parameters in Shale Gas Resource Evaluation

The evaluation methods for shale gas resources and the key parameters involved are diverse. The main research object of this article is the key parameters in shale gas resource evaluation, and this study aims to quantitatively evaluate the required key parameters for calculation, thereby improving the credibility of shale gas resource evaluation results. This article mainly analyzes the weight analysis of the key parameters used in the resource evaluation process, focusing on the analysis and determination of key parameters controlling the generation, enrichment, and preservation of shale gas. The key parameters are graded and evaluated layer by layer, and the common key parameters that participate in the determination are extracted. Based on the above analysis, a weight conversion model is proposed to quantitatively evaluate the actual importance of key parameters in resource evaluation. By combining statistical research, the partial correlation coefficients in the correlation coefficients are applied to estimate the resource quantities in the exploration field in order to quantitatively evaluate the credibility of the resource evaluation results. This article focuses on the weight assignment of key parameters for calculating the resource quantity of the Jiaoshiba shale gas field in the Fuling area of Chongqing and obtains different weight results for different parameters. Using this method to assign key parameter weights to the target block can provide reliable parameter support for shale gas resource evaluation and provide strong support for shale gas resource estimation.

Refractured Well Hydraulic Fractures Optimization in Tight Sandstone Gas Reservoirs: Application in Linxing Gas Field

Poorly producing wells in sandstone gas reservoirs are often refractured to enhance production. Considering the mutual interference of initial/refractured fractures, conductivity dynamic evolution, non-uniform inflow, and variable mass flow in the fracture comprehensively, a semi-analytical reservoir-fracture coupled production model fusing spatial and time separation methods is introduced to model refractured well performance. The proposed model is verified by CMG. The field applications indicate that the refracture job should be carried out when production is lower than the desired value. Restoring the Cf-ini and constructing the Cf-ref can increase productivity, which increases over 8 D•cm. The production growth rate just obtained a slight improvement. The production increased significantly with Lf-ini increasing from 120~270 m and Lf-ref increasing from 100~150 m. Hence, it is essential to extend the Lf-ini under engineering conditions. The ks/km = 10 can obviously increase production, but further enlarging ks does not contribute to well performance. Conversely, further producing larger bs is vital to enhancing production. Subsequently, the optimal parameter combinations (ds > Lf-ini > Lf-ref > Cf-ini > ks > Cf-ref) for well(X1) are carried out by orthogonal experiments. This work proposes a novel method to simulate refractured vertical well performance in tight gas reservoirs for refracture optimization.

Evaluating the radioactivity and health risks in oil and gas production areas: insights from Titas Gas Field, Bangladesh

ABSTRACT Conducting comprehensive studies of radioactivity and associated risk assessments in the oil and gas industry is crucial due to the potential accumulation of Naturally Occurring Radioactive Materials in production operations. This pioneering study investigates radioactivity levels in surface soil from the Titas Gas Field area in Bangladesh by a High Purity Germanium (HPGe) detector, a crucial resource of the nation’s energy infrastructure. In surface soil, the activity of 226Ra, 232Th, and 40K varied from 18–41 Bq/kg, 28–62 Bq/kg, and 280–600 Bq/kg, respectively. Particularly, the levels of 232Th exceeded the global average value for soil. These elevated 232Th levels are likely attributed to a combination of natural geological processes of enriching thorium bearing minerals, geochemical processes favouring thorium retention and human activities selectively impacting these radionuclides. The estimated of radiological risk reveals that some indices exceed recommended limits, hence pose a concern for public health. The study recommends periodic monitoring, public awareness campaigns, remediation efforts, and long-term management strategies to protect environmental and public health. The findings of this research underscore the critical need to recognise and address radiological hazards associated with gas extraction activities to safeguard the health and safety of workers and nearby communities in Bangladesh.

Improving corrosion resistance of super-13Cr martensitic stainless steel by a homogenized amorphous film

Super 13Cr martensitic stainless steel (UNS S41426, S13Cr MSS in the case) developed for gas fields is being applied more broadly. However, the stress corrosion cracking induced by pitting limits its application range. To enhance the corrosion resistance, a new amorphous film was pre-formed on its surface by a modified alkaline solution. The nanoscale amorphous film contained FeO, Fe2O3, Cr2O3 and Cr(OH)3, growing logarithmically after a short dissolution duration. The general corrosion resistance of S13Cr MSS improved significantly, as evidenced by a decrease in corrosion current density by an order of magnitude. Additionally, the pitting potential of S13Cr MSS increased by nearly 100 %. This work provides a strategy for addressing surface defects in S13Cr MSS.

Optical pattern formation of laser fields in the Rydberg atomic gases

We study the phenomena of long-wave and short-wave modulation instabilities (LMI and SMI) in Rydberg atomic gases within the framework of the nonlocal nonlinear Schrödinger equations in the local and nonlocal regions (characterized by the ratio of beam radius to radius of Rydberg blockade sphere), respectively. We further reveal the rich soliton dynamics arising from interactions of nonlinear waves triggered by LMI. We also show the variety of spatial self-organization pattern formations and their active manipulation due to SMI. Through a synthesis of theoretical analysis and numerical simulations, the self-organized optical structures reported here provide a way for realizing what we believe to be novel optical patterns and solitons based on Rydberg atomic gases.

Thickness and Structure of Permafrost in Oil and Gas Fields of the Yamal Peninsula: Evidence from Shallow Transient Electromagnetic (sTEM) Survey

The Yamal-Nenets Autonomous District, especially the Yamal Peninsula located in the permafrost zone, stores Russia’s largest oil and gas resources. However, development in the area is challenging because of its harsh climate and engineering–geological features. Drilling in oil and gas fields in permafrost faces problems that are fraught with serious accident risks: soil heaving leading to the collapse of wellheads and hole walls, deformation and breakage of casing strings, gas seeps or explosive emissions, etc. In this respect, knowledge of the permafrost’s structure is indispensable to ensure safe geological exploration and petroleum production in high-latitude regions. The extent and structure of permafrost in West Siberia, especially in its northern part (Yamal and Gydan Peninsulas), remain poorly studied. More insights into the permafrost’s structure have been obtained by a precise sTEM survey in the northern Yamal Peninsula. The sTEM soundings were performed in a large oil and gas field where permafrost is subject to natural and anthropogenic impacts, and its degradation, with freezing–thawing fluctuations and frost deformation, poses risks to exploration and development operations, as well as to production infrastructure. The results show that permafrost in the western part of the Yamal geocryological province is continuous laterally but encloses subriver and sublake unfrozen zones (taliks) and lenses of saline liquid material (cryopegs). The total thickness of perennially frozen rocks is 200 m. The rocks below 200 m have negative temperatures but are free from pore ice. Conductive features (<10 Ohm﮲m) traceable to the permafrost base may represent faults that act as pathways for water and gas fluids and, thus, can cause a geohazard in the oil and gas fields (explosion of frost mounds, gas blow during shallow drilling, etc.).

Identification of the low resistivity-low contrast (LRLC) gas-bearing pay zones in Shaly sand reservoirs using acoustic data: a case study from the Messinian Abu Madi formation, onshore Nile Delta, Egypt

AbstractDetection of the low resistivity-low contrast (LRLC) reservoirs is among the main challenges in the oil industry. In this concern, the LRLC pay zones of the Upper Messinian Abu Madi clastic reservoirs in the onshore Nile Delta Gas fields became a main challenge for significant exploration. This type of reservoirs, including low resistivity-low contrast zones and thin-bedded intervals, are often overlooked using the conventional petrophysical evaluation techniques, especially in the wildcat exploratory wells or highly agitated shoreline depositional environments like the Nile Delta of Egypt. These hidden low contrast reservoirs are generally challenging due to the presence of many shale intercalations/laminations and/or due to increasing the shale volume represented in the form of dispersed distribution, and the dominance of conductive clay minerals. Therefore, in this study, the expected high resistivity values of the gas-bearing reservoir intervals of the Abu Madi Formation in the onshore Begonia gas Field, as a typical case study of the LRLC reservoirs, are masked due to the relatively high shale conductivity, particularly when the thickness of these intervals is less than the vertical resolution of the utilized conventional resistivity log. To verify the LRLC phenomena of the Begonia gas Field, the obtained data was compared to the South Abu El Naga gas Field as a normal case study with a relatively high resistivity gas-bearing pay zone. To overcome the impact of the conductive clay mineral content and identify these hidden low resistivity reservoir intervals, it is necessary to integrate the conventional logging data (gamma-ray, shallow and deep resistivity, density, and neutron) with the acoustic log data including shear and compressional sonic data. In this way, a useful relationship can be established enabling the detection of these hidden LRLC reservoir intervals. This integration is based on the principle that shear waves are not influenced by the fluids types, whereas the compressional sonic waves are influenced by the reservoir fluids. However, to effectively investigate these concealed LRLC reservoir intervals, which can boost production and increase the potential reserves, it is essential to have a low water cut value. The present study represents introduces an efficient workflow, which can be extended to other similar LRLC pay zones in the Nile Delta and northeast Africa. It is also extendible to the LRLC reservoirs in similar deltaic systems having conductive minerals-bearing reservoirs or thin beds.

Review on the Study of Microscopic Pore Structure and Seepage Characteristics

Pore structure, as the focus of researchers, is also one of the main contents of reservoir geological research, and the characteristics of percolation depend on the micro-pore structure of the reservoir. The study of the characteristics of fluid percolation in the reservoir plays an important role in formulating a reasonable oil and gas exploitation scheme. Understanding the micro pore structure of the reservoir, analyzing the pore throat structure inside the oil and gas reservoir, and systematically studying the micro seepage characteristics of the reservoir have far-reaching influence and great significance for the exploration and development of oil and gas fields.

Fluid Mechanics of Gas-Liquid Systems

The study of gas-liquid systems in fluid mechanics is essential for understanding multiphase flows, particularly in industries such as oil and gas field development. This research explores the key parameters that govern the behavior of such systems, including volume flow, velocity, area, dynamic viscosity, and diameter. Volume flow represents the quantity of fluid moving through a system per unit time, while velocity determines the rate at which the fluid particles travel. The cross-sectional area of the conduit directly influences the flow regime, and the dynamic viscosity defines the fluid's internal resistance to flow, significantly impacting pressure drops and flow patterns. The pipe diameter plays a critical role in determining flow characteristics such as Reynolds number and transition between laminar and turbulent flow. By analyzing these factors, this study provides insights into optimizing gas-liquid systems for improved performance and efficiency in industrial applications.

Predicting thermochemical sulfate reduction reaction process and H2S generation in carbonate reservoirs using comprehensive kinetics modeling

Thermochemical sulfate reduction (TSR) is a critical process controlling hydrogen sulfide (H2S) generation in carbonate reservoirs, posing significant economic and safety challenges for the oil and gas industry. This study develops a comprehensive model that integrates detailed thermal, burial, and hydrocarbon generation histories with key TSR kinetic parameters, such as reaction rate constants and activation energies, to predict TSR evolution and H2S generation accurately. A notable feature of the model is to separate and quantify the contributions of different hydrocarbon species (CH4, C2-5, C6-14, and C15+) to the overall TSR process, using the Arrhenius equation to simulate the temperature-dependent behavior of TSR for each hydrocarbon group. The model also accounts for the in-reservoir thermal cracking of heavier hydrocarbons into light hydrocarbons, ensuring predictions closely align with geological processes. Modeling results show that TSR reactions accelerate the depletion of oil and wet gas components. A large amount of CH4 is generated due to both kerogen thermal cracking and alteration of heavy hydrocarbon. Our modeling also allows for accurate prediction of TSR reactions as well as the timing and extent of H2S and CO2 generation over the history of a reservoir. Applications in the Puguang and Hetianhe gas fields validate the model's broad applicability and reliability, capturing extensive TSR activities and being consistent with the observed data. These results underscore the models' robustness in detailed predictions of TSR dynamics across diverse geological settings and its potential as a valuable tool for managing sour gas production, aiding in risk assessment and resource management.

Gas-bearing evaluation of deep coal rock in the Yan’an gas field of the Ordos Basin

Gas-bearing evaluation of deep coal rock in the Yan’an gas field of the Ordos Basin

Three-dimensional reservoir modeling of the pliocene reservoir based on seismic data advances for new prospect assessment

This study presents a comprehensive characterization of the Pliocene reservoir formation in the Temsah gas field, located 65 km NNW of Port Said in the northeastern Nile Delta Basin. The research integrates seismic data with well log analysis to enhance reservoir characterization. The Temsah gas field is distinguished by its intricate geological structure, featuring numerous normal faults oriented along northeast-southwest and northwest-southeast trends. The field’s stratigraphy is predominantly composed of sandstone and shale facies, which are considered highly prospective for hydrocarbon accumulation. A full geological field analysis was conducted to identify key prospects for enhancing productivity. To accurately delineate seismic features, data from four wells and twenty-nine 2D seismic lines were interpreted. Depth maps of the reservoir layers were constructed, highlighting critical transitions between sandstone and shale facies, which are pivotal for future exploration efforts. A detailed 3D static model was developed to illustrate the impact of lithological composition on reservoir characteristics, with a specific focus on the Upper Sand of Kafr El-Sheikh Formation. Petrophysical properties, including effective porosity (13–23%), shale content (7–31%), and water saturation (30–45%), were meticulously evaluated to inform the creation of a robust 3D property model. This model provides a detailed spatial distribution of rock facies and petrophysical parameters within the Temsah gas field. The integration of these studies identified two promising areas, with estimated original gas in place (OGIP) ranging from 2.86 to 4.04 stock cubic feet (SCF), indicating significant potential for field development and enhancement.

EXPERIMENTAL STUDY ON THE FRACTURE CONDUCTIVITY IN SHALE OIL PRODUCTION

Unconventional oil and gas resources, such as shale oil and gas, are gradually attracting great attention from all countries of the world. Horizontal drilling and large-scale hydraulic fracturing technology are used to efficiently extract oil from shale formation. Effective placement of the proppant in the fractures and high long-term conductivity are the keys to solve the problems of oil well flow rate increase in shale oil and gas fields. In this work, the sieve analysis method and FCMS-V fracture conductivity determination device, as well as scanning electron microscope are used. They are used to experimentally investigate the filtration characteristics of hydraulic fracturing fractures and establish the key factors affecting the filtration characteristics. The object of the study is the core of the oil-saturated DG shale formation of Songliao Basin. Also in this paper, the indentation and crushing mechanism of proppant under reservoir conditions is studied. The influence of various factors was evaluated qualitatively and quantitatively. The following studies were conducted: the effect of sand granule size on conductivity, the effect of grain size distribution on conductivity, the effect of proppant concentration on conductivity, the effect of fracture closure pressure on conductivity, and the effect of proppant indentation on conductivity. The granule sizes of the proppant used range from 30/50 to 70/140 mesh. Proppant concentration: 2,5; 5; 10 kg/m2. Ratios of granule sizes for used mixtures: 1:1:1, 1:2:7, 1:4:5.And crack clamping pressure from 20 to 40 MPa. As a result of the study, dependences of initial and long-term fracture conductivity on clamping pressure, granulometric composition of proppant and its concentration were obtained. Using a scanning electron microscope, the degree of indentation and crushing of proppant under reservoir conditions in two media, namely shale core and steel plates, was visually evaluated. The results of experimental studies can be used to optimize the shale oil development system and have scientific and practical significance for shale oil production in continental deposits.

THREADED LUBRICANTS FOR DRILL PIPES BASED ON OIL PRODUCTION WASTE

The oil and gas industry occupies a leading position in the development of the country's fuel and energy complex, and the effectiveness of its activities largely depends on the technical and economic indicators of drilling. When performing well work and operating oil and gas wells, many material costs are associated with the operation of oil pipes, namely the reliability of threaded connections operating at high pressures and temperatures in aggressive environments. The need to develop deeper and deeper horizons, the use of forced drilling modes, the transition to later stages of operation of most oil and gas fields, the aging of existing funds and the increase in the volume of overhauls leads to an increase in tripping operations, and therefore the requirements for the reliability of the connection of oil-grade pipes are moving to a new level. Studies have shown that up to 87 % of all drill string accidents are related to poor thread condition. This unsatisfactory condition of the locking threaded joints forces us to look for ways to improve durability. Many foreign and domestic scientists have been studying and improving threaded joints in drill pipes. According to the authors, one of the most promising ways to increase the TEI of drilling is to develop and use more and more effective lubricants for locking joints of drilling tools. Studies have shown that conventional lubricants are not effective enough in modern realities, and sometimes lubricants are completely washed out of threaded joints. In addition, as the drilling depth increases, the friction force increases and the hydrodynamic load increases, and the increase in pressure in the threaded connection complicates the conditions due to the effect on the lubricant of chemically active and abrasive drilling muds and many other factors. The article discusses the obtained results of studies of lubricant bases for threaded connections of drill pipes used for the oil industry, the distinctive features of which are physical and chemical composition, including low molecular weight polyethylene, synthetic rubber, rubber softeners, powdered graphite, vegetable oils.The authors of the article selected the basis of lubricant from industrial rubber production waste, and also presented the advantages of the developed lubricants and materials. The practical significance of the obtained research results lies in the possibility of increasing the wear and sealing properties of threaded pipe joints used in drilling oil and gas wells.

Application of convolutional long short-term memory for spatio-temporal forecastings of hydrocarbon saturations and pressure in oil fields

A machine learning architecture composed of convolutional long short-term memory (convLSTM) is developed to predict spatiotemporal parameters, that is, saturation and pressure in an oil & gas field namely, the SACROC field in Texas, USA. The spatial parameters are recorded at the end of each month for 360 months, approximately 83% of which is used for training and the rest 17% is kept for testing. The samples for the convLSTM models are prepared by choosing ten consecutive frames as input and ten consecutive frames shifted forward by one frame as output. A workflow is provided describing the entire process of data extraction, preprocessing, sample preparation, training, testing of machine learning models, and error analysis. The structural similarity index measure (SSIM) and normalized root mean squared error (NRMSE) are calculated during training and testing for quantitative error analysis. During the training phase, the predicted frames demonstrate a strong resemblance to the ground truth frames. Moreover, it exhibits superior performance during the initial months of testing. As testing progresses into the later months, deviations increase as errors accumulate over time for relying on past predictions. In summary, convLSTM for spatio-temporal prediction offers significant potential for forecasting and optimizing hydrocarbon recovery from porous media.

Study on the Mechanism of Algae Bacteria Symbiotic System in Treating Fracturing Flowback Fluid

Fracturing operations in oil and gas wells are one of the main measures to increase production. Fracturing flowback fluid has the characteristics of high viscosity, high COD value, and containing multiple chemical reagents, making it difficult to treat. It has become one of the main pollutants in oil fields. Directly discharging untreated fracturing fluid can cause serious pollution to the environment and soil. Therefore, in-depth research on the treatment methods of fracturing flowback fluid is of great significance for environmental protection and cost reduction in oil and gas fields. This article systematically analyzes the sources, components, pollution characteristics, and treatment status of fracturing flowback fluid. The efficient treatment of fracturing flowback fluid using a microalgae aerobic bacteria mixed culture system was conducted, and the mechanism of algae bacteria symbiotic treatment of oily wastewater and the mechanism of microalgae aerobic bacteria mixed culture purification of fracturing flowback fluid were analyzed in depth.

ON FEASIBILITY OF AZEOTROPIC SYSTEM USING TO IMPROVE DIETHYLENE GLYCOL REGENERATION QUALITY

The main technological scheme for dry natural gas treatment is absorption drying with diethylene glycol (DEG) vacuum regeneration. The final stage of field development is characterized by low flow rates and high moisture content of the gas, leading to load increase on gas drying devices and the DEG regeneration unit, resulting in deterioration in the quality of the regenerated DEG. This is due to DEG contamination with mechanical impurities, organic salts, products of its resinification and decomposition.In conditions of declining gas production at the fields of the Cenomanian deposits of theFar North, one of the possible variants of DEG regeneration processes efficiency increasing is the transfer of glycol regeneration units to operate according to the azeotropic distillation scheme.The objects of the study are water-saturated glycol regeneration units used in absorption units of gas fields. The issues of technological efficiency of water-saturated glycol regeneration unit operation according to existing schemes are considered and feasibility of their transfer to the use of azeotropic distillation is given.

EXPERIMENTAL STUDY OF HYDRATE FORMATION PECULIARITIES FOR CONDITIONS OF THE TURNO AND CENOMANIAN DEPOSITS: Part II

This paper is the second part of the research devoted to the study of hydrate formation features for the conditions of Turonian and Cenomanian deposits. The launch of new gas projects at the Turon and Senoman production facilities in Western Siberia provided a good opportunity to critically analyze the known methods of protecting production, gathering and transportation facilities of the gas field from the formation of solid gas hydrates. The paper presents the experience of implementing a program of laboratory studies of conditions of gas hydrate formation with their subsequent processing and in-depth analysis. The research program covered the area of thermobaric parameters typical for the conditions of Turon-Senoman deposits exploitation with localization of hydrate-hazardous areas in the conditions of Technological Regimes for full development. The description of laboratory studies is given, in which two gas compositions of Senoman and Turon objects, different variants of mineralization and ionic composition corresponding to formation and condensation water, as well as hydrate formation conditions under changing dosages of basic inhibitor on the basis of methanol were considered. The details of the experiment based on the method of swinging cells and the subsequent analysis of the results of the completed experiments to determine the thermobaric conditions of formation and decomposition of hydrates are given. The main features of the experiment are specified, estimates of the rate of change of the influencing parameters of the experiment on its quality are given. In the process of implementation of the experimental program, the optimal values of these parameters were selected, which allowed us to significantly reduce the variation of experimental results to determine the thermobaric conditions of hydrate formation. It is experimentally established that the temperature of hydrate decomposition is higher than the temperature of its formation at all investigated gas compositions and water mineralization.

Data-driven multiscale geomechanical modeling of unconventional shale gas reservoirs: a case study of Duvernay Formation, Alberta, West Canadian Basin

The Duvernay Formation in Canada is one of the major oil and gas source formations in the Western Canadian Sedimentary Basin, located at its deepest point. While it demonstrates promising development potential, challenges arise in the urgent need for integration of geology and engineering models, as well as in optimizing sweet spots, particularly as infill wells and pads become central operational objectives for the shale gas field. A lack of the geomechanical understanding of shale gas reservoirs presents a significant obstacle in addressing these challenges. To overcome this, we implemented data acquisition and prepared historical models and profiles, resulting in an extended high-resolution geological and reservoir property model with a fine grid system. Subsequently, a 3D full-field multi-scale geomechanical model was constructed for the main district by integrating seismic data (100 m), geological structures (km), routine logs (m), core data (cm), and borehole imaging (0.25 m), following a well-designed workflow. The predicted fracturability index (brittleness) ranges from 0.6 to 0.78, and a lower horizontal stress difference (STDIFF) is anticipated in the target formation, Upper Duvernay_D, making it a favorable candidate for hydraulic fracturing treatment. Post-analysis of the multi-disciplinary models and various data types provides guidelines for establishing a specific big database, which serves as the foundation for production performance analysis and aggregate sweet spot analysis. Fourteen geological and geomechanical candidate parameters are selected for the subsequent sweet spot analysis. This study highlights the effectiveness of multi-scale geomechanical modeling as a tool for the integration of multi-disciplinary data sources, providing a bridge between geological understanding and future field development decisions. The workflows also offer a data-driven framework for selecting parameters for sweet spot analysis and production dynamic analysis.

Application of sculptured Mn conical (Spiral+helical) thin films for monitoring N2-CO and N2-CO2 gas mixtures: Gas ionization and field emission sensors

This study deals with the design and fabrication of Mn sculptured conical (spiral + helical) thin films as electrodes for the detection of gas mixtures of different percentages (N2-CO and N2-CO2) in a gas ionization and field emission face to face sensor. The electrodes were produced using oblique angle deposition (OAD) technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and field emission electron microscopy (FESEM) as well as energy dispersive x-ray spectroscopy (EDS) confirmed crystallography, morphology and elemental composition of materials of the designed samples. The sharp tip of the nano-helices were aimed to act as an electric field enhancer by applying voltage. The results indicated that Paschen's law is not applicable for inter-electrodes gaps less than 15 μm at pressures higher than 250 mbar where the field emission process becomes the dominant reaction. Enhanced selectivity and sensitivity were obtained for CO, CO2 and their mixtures with N2 gas at lower concentrations and shorter inter-electrodes gaps (<100 μm). The ionization energies of different ionization channel reactions of N2, CO and particularly CO2 in the gas mixtures were used to explain the behavior of Paschen's curves in different pressure ranges. Highest sensitivity of the sensor was obtained for inter-electrodes gaps of less than 100 μm. Comparison of the results with the published literature showed better performance of the present sensors relative to previously reported works.