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- North America > United States > Texas (0.67)
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- Geology > Structural Geology > Tectonics > Plate Tectonics (1.00)
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- Asia > Russia > Ural Federal District > Yamalo-Nenets Autonomous Okrug > Purovsky District > West Siberian Basin > Nadym-Pur-Taz Basin > Block V > Urengoyskoye Field > Achimov Formation (0.99)
- Asia > Russia > Ural Federal District > Yamalo-Nenets Autonomous Okrug > Purovsky District > West Siberian Basin > Nadym-Pur-Taz Basin > Block IV > Urengoyskoye Field > Achimov Formation (0.99)
- Asia > Russia > Ural Federal District > Yamalo-Nenets Autonomous Okrug > Purovsky District > West Siberian Basin > Nadym-Pur-Taz Basin > Block 5A > Urengoyskoye Field > Achimov Formation (0.99)
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- Well Drilling (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
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Effects of Drilling Number and Distribution on Fracture Using the Pulse Plasma on Tight Sand Reservoir
Li, Zhaoxuan (Petroleum and Gas Engineering, LiaoNing Petrochemical University) | Wang, Shuo (Petroleum and Gas Engineering, LiaoNing Petrochemical University) | Pan, Yi (Petroleum and Gas Engineering, LiaoNing Petrochemical University (Corresponding author)) | Zhang, Rongqi (Petroleum and Gas Engineering, LiaoNing Petrochemical University) | Chen, Jiajun (Petroleum and Gas Engineering, LiaoNing Petrochemical University)
Petroleum and Gas Engineering, LiaoNing Petrochemical University Summary The permeability of unconventional reservoirs is extremely low, resulting in their drainage area being limited to tens of feet. Therefore, researchers have developed an effective stimulation technology that can be used in combination with conventional hydraulic fracturing, namely, pulsed plasma fracturing technology. Pulsed plasma fracturing technology is an efficient and environmentally friendly auxiliary hydraulic fracturing stimulation technology. However, most existing studies have focused only on the effect of pulsed plasma fracturing on single wells, ignoring the effect of the number and distribution of wells drilled on pulsed plasma fracturing. In this paper, pulsed plasma fracturing is studied by a self-built pulsed plasma experimental platform and nonlinear finite element software. First, the generation and propagation mechanism of shock wave, fracture type, and stress field analysis of rock mass in pulsed plasma fracturing technology are discussed. The double-well experiment was carried out by using the experimental platform, and the fracture law of fractures under different wellhead distribution conditions was obtained. In addition, a multiwell mathematical model is established by using the combination of the Euler method and Lagrange method to simulate the interaction between fluid and solid, that is, arbitrary Lagrangian Eulerian (ALE) multimaterial fluid-solid coupling method and the influence of drilling times and wellhead distribution on pulsed plasma fracturing is discussed. Stress analysis shows that the rock is mainly affected by ground stress, liquid column pressure, and shock wave pressure. The experimental results show that the discharge voltage is positively correlated with the shock wave pressure on the rock. The distribution of different wellheads affects the distribution and length of fractures. The double-well experiment makes the fractures easier to fracture. The simulation results show that the fracture length in the connection direction of the two wells is longer, and the fracture length in the vertical direction is shorter. This shows that the number and distribution of drilling affect the initiation and propagation of fractures. Introduction Nowadays, with the increasing demand for oil and gas resources, conventional oil fields have entered a period of exploitation attenuation (Asif and Muneer 2007; Li et al. 2017; Williamson and Esterhuyse 2020; Madon 2020).
- Research Report > Experimental Study (0.68)
- Research Report > New Finding (0.54)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.84)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.34)
- Asia > China > Shandong > North China Basin > Shengli Field (0.99)
- Asia > China > Liaoning > Bohai Basin > Liaohe Basin > Liaohe Field (0.99)
- Asia > China > Henan > Gucheng Field (0.99)
- Asia > China > Hebei > Bohai Basin > Huabei Field (0.99)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.93)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.88)
Enhancing Fracture Conductivity in Soft Chalk Formations With Diammonium Phosphate Treatment: A Study at High Temperature, Pressure, and Stresses
Desouky, Mahmoud (Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals) | Aljawad, Murtada Saleh (Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals) | Abduljamiu, Amao (Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals (Corresponding author)) | Solling, Theis (Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals) | Abdulraheem, Abdulazeez (Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals) | AlTammar, Murtadha J. (Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals) | Alruwaili, Khalid M. (Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals)
Summary This study aims to address the problem of fracture hydraulic conductivity decline in soft formations using a diammonium hydrogen phosphate (DAP) solution. A naturally weak carbonate, Austin chalk was chosen as an ideal specimen. Flat chalk samples with reduced elastic modulus and roughness were evaluated before and after aging with 1 M DAP for 72 hours at 75°C and 1,000 psi. The fracture gas conductivity of DAP-aged and untreated samples was measured at various flow rates and stresses while recording sample compaction using linear variable differential transformers (LVDTs). The study found that DAP aging increased the reduced elastic modulus of chalk specimens up to 330% of the original value, improving their resistance to deformation and failure under stress by 200 psi. The hydraulic conductivity of DAP-aged samples was at least twice that of untreated samples, with an extended hydraulic fracture conductivity seven times higher than that of the untreated ones. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis revealed that DAP reacted with the chalk to form hydroxyapatite (HAP), which binds the calcite grains, yielding a stiffer, more deformation-resisting rock surface. Overall, the study demonstrates the potential of chemically enhancing and extending the fracture hydraulic conductivity of weak carbonates using DAP.
- North America > United States > Texas (1.00)
- Asia (1.00)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (0.88)
Cracking Evolution for Deep Hard Coal Using X-Ray In-Situ Micro-CT Technology and Fractal Theory
Zhang, Liang (Deep Mining and Rockburst Research Institute, CCTEG Chinese Institute of Coal Science, Beijing, China State Key Laboratory Cultivation Base for Gas Geology and Gas Control, Henan Polytechnic University, China) | Li, Xiaopeng (Deep Mining and Rockburst Research Institute, CCTEG Chinese Institute of Coal Science, China) | Qi, Qingxin (Deep Mining and Rockburst Research Institute, CCTEG Chinese Institute of Coal Science, China) | Li, Haitao (Deep Mining and Rockburst Research Institute, CCTEG Chinese Institute of Coal Science, China)
ABSTRACT: Rockburst poses severe threats to the deep mining of coal mines in China; however, the fracture mechanism of deep hard coal is still unknown. Hence, this paper focuses on the cracking evolution laws for deep hard coal with high-bursting liability utilizing X-ray in-situ micro-CT technology and fractal theory. The in-situ micro-CT scanning system and bursting liability indexes for deep hard coal are first introduced in this work. Then, the uniaxial compressive experiments for the coal samples using in-situ CT scanning are conducted. Furthermore, the crack initiation, propagation, and coalescence of coal are revealed based on the in-situ micro-CT scanning experiment results. The 3D digital core of coal is obtained; four typical parameters, including fracture volume fraction and fractal dimension in 2D and 3D, are used to characterize the fracture network evolution for deep hard coal during the progressive failure process. The findings are valuable in rockburst, damage, and fracture mechanics. GENERAL LAYOUT This manuscript contains five chapters, i.e., introduction; experiments and results; discussion; conclusions; acknowledgements; references. There are three figures, one table, and 15 references. INTRODUCTION Coal is a fundamental energy resource in China; however, with the increase in mining depth and coal demand, rockburst usually occurs during underground mining as a deadly dynamic hazard. It is reported that there are 144 coal mines facing rockburst hazards in China. Even though there are considerable challenges to understanding the mechanical mechanism of rockburst, it is vital to mining safety. Rockburst is a dynamic phenomenon that results from the sudden and violent failure of coal or rock mass, accompanied by tremendous sound. Numerous investigations have been carried out to analyze the mechanism of rockburst, and various theories have been proposed involving the theory of strength, stiffness, energy, and bursting liability. Additionally, the three primary factors theory, i.e., high stresses, discontinuous structure planes, and coal or rocks mechanics properties, has been proven to be one of the successful theory methods in terms of the rockburst mechanism. For coal mines in China, four mechanical parameters, including duration of dynamic fracture, elastic strain energy index, bursting energy index, and uniaxial compressive strength, have been widely used to define the bursting liability of coal. Furthermore, the control measures of rockburst, such as high-pressure coal seam infusion, drill hole destressing, and roof hydraulic fracturing, have been suggested as effective control methods by coal mine engineers in China.
- Materials > Metals & Mining > Coal (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.89)
- Well Drilling > Wellbore Design > Rock properties (0.56)
ABSTRACT: Hydraulic fracturing (HF) has emerged as a widely used ground control strategy in Chinese coal mining practice, often employed in combination with ground support techniques. HF campaigns can be broadly categorized into two types based on the size of the targeted region: local campaigns, which are applied to smaller areas such as the roof above a coal pillar, and large-scale campaigns, which encompass a broader area, such as the entire width of a longwall panel. This paper presents two case studies that examine the use of both local and regional HF as a ground support strategy in Chinese coal mines. The field studies demonstrate that HF is effective in reducing or redistributing mining-induced stresses, preconditioning hard rock strata, and, in some cases, decreasing mining-induced microseismicity. INTRODUCTION In contrast to civil tunnels, underground coal mine roadways possess a distinctive characteristic: they are unavoidably subjected to mining-induced stresses, particularly in the entries of longwall panels. As the longwall extraction proceeds, abutment stresses form around the periphery of the mined-out area. The presence of high abutment stresses can result in a range of problems concerning the stability of longwall entries and pillars, such as roof fall, rib failure, floor heave, and even coal burst. At greater mining depths, these challenges become more pronounced owing to the high overburden stresses associated with the relatively brittle response of coal measures. Thus, the development of protective measures to counteract the damaging effects of excessive stresses is necessary. Destress blasting is a long-established stress relief technique utilized in underground coal mining. Its primary objective is to shift stress concentration zones to the interior rock mass and establish a protective barrier surrounding the excavation (Konicek et al., 2011). In China, destress blasting was successfully implemented to control floor heave in deep coal mines (Kexin, 1995; Xia et al., 2007), as well as to mitigate coal burst issues in Poland, the Czech Republic, China, and Germany (Konicek et al., 2011; Dvorsky et al., 2005; Gu et al., 2016; van As et al., 2004; Catalan et al., 2012). The technique is believed to release stored strain energy and reduce modulus values, thereby ensuring that the rock mass does not bear a critical stress level (Sedlak, 1997).
- Materials > Metals & Mining > Coal (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Louisiana > China Field (0.89)
- Europe > Germany (0.89)
- Europe > Czech Republic (0.89)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
ABSTRACT: The paper is intended to pay homage to Professor Leopold Müller who was a leading developer and user of physical models. This will be done by reviewing physical models of fundamental material behavior, geologic mechanisms, and especially jointed rock. On this basis complex models of geologic processes and of structures on and in rock masses will be discussed. As will be shown this sequence of topics also corresponds to the history of physical models. Finally, critical aspects, namely the issues of scaling and of obsoleteness because of powerful simulation models will be addressed leading to the outlook as to where physical models can and should be used. INTRODUCTION The paper is intended to pay homage to Professor Leopold Müller who was a leading developer and user of physical models to solve fundamental rock mechanics problems and complex engineering cases. Professor Müller not only used Physical Models extensively but also wrote a seminal paper (Müller,1980), in which he discussed other types of models and addressed the skepticism with which physical models were looked at. Today we face a similar situation in that the use of physical models is questioned in comparison to the possibilities of powerful computer-based simulations. I intend to address this issue by looking at models of materials, of geologic processes, and of jointed rock masses to end up with complex models such as slope instabilities and tunnels in rock masses. This sequence of model topics also fits well into the history of physical models. Finally, to bring physical modeling into the context of present-day engineering and science the paper will compare the principles and use of physical models with those of simulation models. MATERIAL MODELS To start this section the discussion (dialogo secondo) by Galileo Galilei (1638) on bending (Fig. 1) is used. Figure 1 is not the picture of a physical model but of a conceptual one. It is used because it shows two aspects (among others) of Galilei's interpretations: The correct one is related to scaling: multiplying (e.g., doubling) the dimensions does not increase the loading capacity by the same factor. The incorrect one is the assumption that the tensile stresses are uniform at section A-B. If a physical model test had been run this mistake would have been discovered. This is a pertinent lead-in to the paper – PHYSICAL MODELS AND SCALING OF PHYSICAL PROCESSES are essential.
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
ABSTRACT: As underground mines go deeper, it is of utmost importance to manage increased stresses to minimise occurrences of rockbursts. Rockbursts have several documented devastating economic, social and safety consequences such as fatalities, loss of mine assets or production sections, social uproar, force majeure etc. Among several approaches which can be adopted to manage rockbursts is the practice of destress blasting. It is necessary to evaluate the efficiency of any adopted destress blasting design. This can be done through the measurement of physical parameters such as changes in deformation, local seismic magnitude, stress; fracturing intensity etc. at different locations where destress blasting has been implemented. This entails physical exposure of workers to mining excavations, increasing their exposure to harm when safety fails. This paper presents a conceptual study on geostatistical approaches which can be utilized to estimate unmeasured locations using measured locations, thereby reducing the mining personnel's exposure to harm. INTRODUCTION Deep hard rock mining faces the challenges of rockbursts due to increasing stresses and deformations at depths. When the accumulated stress is not properly managed, the resultant rockbursts can lead to severe consequences such as fatalities, loss of expensive equipment, loss of mine production sections, social uproar, and force majeure among many other consequences. Among the alternatives to manage the high stresses and deformations is the practice of destress blasting. Destress blasting aims to move peak stress from the immediate vicinity of the mining drift further into the rock mass (Roux et al. 1958). To come up with a suitable destress blast design, accurate information on the rock mass properties, excavation geometry, stress regime, blast hole dimensions and explosives characteristics is needed. To assess the efficiency of destress blasting, different approaches can be used, these include, numerical simulation, fracture frequency monitoring ahead of the mining face (using a borehole camera, ground penetrating radar or physical assessment of the mining face drill core) before and after destress blasting, deformation monitoring using laser scanning among many other approaches. Figure 1 illustrates fracture frequency measurement using borehole periscope (a) and physical assessment of drill core (b). c represents a scale which can be used to assess rockburst potential based on fracture frequency measurement.
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
Generation of a Discrete Fracture Network from Digital Discontinuity Data Captured Using the 3D Axis Mapping Method
Morgenroth, Josephine (RockMass Technologies, Canada) | Hazzard, Jim (ITASCA Consulting Group Inc., USA) | Yee, Shelby (RockMass Technologies, Canada) | Elmo, Davide (University of British Columbia, Canada)
ABSTRACT: Accurate mapping of geological structures and their orientations is a crucial step for analysis of underground excavation stability. A case is presented of a novel digital mapping workflow for generating a discrete fracture network (DFN) model. The RockMass Eon applies the 3-Dimensial Axis Mapping (3DAM) method to capture orientations and locations of discontinuities, producing a statistical distribution of their natural variability. The Eon uses infrared LiDAR and an altitude heading reference system to capture a point cloud, and a clustering algorithm is applied to extract statistically significant orientations representing the discontinuities. In this case study, 83 measurements are generated for 12 structures to provide a statistical dataset of the discontinuities. The mapped data from Glencore Kidd Operations in Canada are imported into ITASCA software to generate a DFN. This paper demonstrates that the use of digital data collection can streamline analyses and increase model confidence in underground rock engineering. INTRODUCTION Complex numerical models are becoming widespread in industry as computational power increases, while simultaneously digital mapping tools to capture discontinuity data are improving. The confluence of increasing data fidelity and improved computational power is making the development of discrete models more accessible to practicing rock engineers. Numerical modelling of rock masses as discrete systems allows for the simulation of rock mass behaviour as a combination of failure through intact rock and displacement along discontinuities. In the discrete approach, a pre-fractured rock mass is represented as an assemblage of discrete blocks, and discontinuities are represented as the interfaces between these blocks. In the current state of practice, an identified limitation of developing discrete models is that insufficient mapping data is available to develop statistically significant distributions from which the discrete models can be generated. Previous research has demonstrated the appropriate field characterization of the discontinuities, since the success of these complex models largely depends on the geological assumptions used to build the underlying Discrete Fracture Network (DFN) (Elmo et al., 2013). A significant limitation to the specific field data collected is the limited availability of geotechnical measurements and the inherent error associated with manually collected compass measurements. It is important to efficiently capture sufficient data for a meaningful DFN model and to improve the data collection procedure (quantity and quality of data being collected). Increasing the population of sampled fractures would increase the degree of knowledge and improve our understanding of variability. As discussed by Elmo et al. (2016), the underlying degree of uncertainty with respect to rock mass blockiness can be reduced by updating the estimated fracture size distribution and mapping fracture terminations to better characterize the structural character of the rock mass. This requires implementing a systematic mapping of 2D rock exposures as development drifts are excavated.
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.90)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (0.84)
A Noninvasive Approach for Quantitative Evaluation of Geological Deformations and Dynamic Disasters in Complex Mining Environments
Khan, Majid (University of Science and Technology Beijing) | He, Xueqiu (University of Science and Technology Beijing) | Song, Dazhao (University of Science and Technology Beijing)
School of Civil and Resources Engineering, University of Science and Technology Beijing, 100083, Beijing, China Summary The escalating demand for deep underground energy sources, driven by the depletion of shallow resources, has raised concerns about the occurrence of dynamic disasters, which pose significant societal risks. In the context of engineering excavation processes, the presence of preexisting and excavation-induced fractures significantly influences the evolution of complex geological disasters associated with mining activities. Traditional approaches to disaster prediction rely heavily on physical models and numerical simulations. However, these methods often suffer from limitations such as time-consuming and uneconomical drilling tests, as well as restricted coverage. To overcome these challenges, this study introduces a novel methodology that enables comprehensive imaging of the geological response, deformation patterns, and dynamic disaster prediction within the entire minefield of underground engineering works with a special emphasis on steeply inclined and extremely thick coal seams (SIETCS). Introduction With the progressive excavation, the reorganization of the in-situ stresses and formation of high stress concentration regimes complicate the mining operation which result in the movement of coal/rock layers leading to dynamic disasters including coal-rockburst, outburst, and collapse [1,2].
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.92)
- Geology > Geological Subdiscipline > Geomechanics (0.68)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Metals & Mining > Coal (0.92)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.70)
Abstract For hydraulic fracturing of low permeability dry gas formation, capillary discontinuity at the matrix-fracture interface and fluid entrapment in the hydraulic and natural fractures can impact the effective fracture half-length and thus result in loss of fracture conductivity. Adding surfactant-based novel fluids can reduce the capillary trapping of fluids by lowering the surface tension and modifying wettability to less water-wet condition and thereby improve the relative gas permeability and well productivity. In this work, a novel surfactant-based fluid was developed to be effective in reducing water entrapment. The surfactant formulation was evaluated in various reservoir conditions including Eagle Ford, Permian, Duvernay, Kansas St. Louis, and Bakken. The new formulation showed excellent stability under harsh reservoir conditions up to 150 °C and 27% TDS. Additionally, a laboratory workflow was developed to evaluate the efficiency of surfactant formulations in the mitigation of water entrapment using two-phase coreflood (CF). Our results show that three formulations (A, B and C) reduce the surface tension comparably. However, in the liquid recovery test using CF, formulations B and C outperformed A, resulting in much higher recovery of the aqueous fluid compared to the control case of formation brine. Wash-off tests were further performed by flushing the cores with fresh brine after treatment with novel formulations. The core treated with formulation C outperformed B after 5 pore volume (PV) flush of brine. Notably, for the core treated with formulation C, even after flushing with 140 PV of brine, the fluid recovery is still much higher compared to the brine case without treatment. Interestingly, formulation C performs even better in the harsh reservoir condition with high salinity brine, which can be explained by the three different adsorption patterns governing the interaction energy between surfactant and rock surface. This work demonstrates that tailoring fluid-rock interactions is crucial to reduce the water entrapment and thereby improve gas productivity for dry gas wells. Our workflow provides a comprehensive process to understand the mechanisms behind water entrapment and how to tailor novel formulations to reduce water entrapment in dry gas wells.
- Asia > Middle East (1.00)
- North America > United States > Texas (0.94)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (0.66)
- Geology > Geological Subdiscipline > Geomechanics (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.30)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.46)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- (3 more...)