bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleation of Instability on Granitoid Faults Under Hydrothermal Conditions: Implications for Fluid Injection-Induced Seismicity
Authors: Huang Rui , Zhang Fengshou , An Mengke , Elsworth Derek 
Published: August 2024

ABSTRACT:
Typical in the development of enhanced geothermal systems (EGS), fluid injection for hydraulic stimulation and fracturing hosts the potential for induced seismicity by reactivating deep faults. We use granite cores from the Pohang EGS site in low velocity shear experiments on simulated fault gouges at confining stresses of 110 MPa, temperatures of 100-250 °C and fluid pressures of 21-80 MPa. These experimental conditions are representative of deep geothermal reservoirs and allow the influence of variations in temperature and effective stress to be explored on the nucleation of instability. Our observations document a transition from velocity-strengthening to velocity-weakening response when both the temperature was raised from 100 to 250 °C and the effective confining pressure was reduced from 89 to 30 MPa. Shear deformation localizes in a narrow shear zone with this increased temperature and a transition from fault compaction to dilation evolves with reduced effective stress – congruent with the transition to velocity weakening. These results suggest that high temperature and low effective stress both favor nucleation of earthquake ruptures during fluid injection. Thus, controlling fluid overpressures and being aware of anomalously high thermal gradients potentially enable important controls to be applied in mitigating such injection-induced seismic risks.

1. INTRODUCTION
Fluid injection into the deep subsurface is capable of activating nearby faults and triggering seismicity. This phenomenon has been widely reported in numerous underground projects - including for enhanced geothermal systems (EGS), wastewater disposal and shale gas development (Elsworth et al., 2016; Grigoli et al., 2018; Walsh & Zoback, 2015; Bao & Eaton, 2016). For mature faults present in such projects, the frictional properties of the fault typically control fault rupture and seismic response (Ikari et al., 2011; Niemeijer & Collettini, 2014). Thus, detailed characterizations of the evolution of fault strength and stability under hydrothermal conditions are crucial in understanding and mitigating such seismic risk for induced earthquakes.
Casing Force Analysis During MPC Waiting Setting Stage Considering the Cement Hydration and Heat Release Process
Authors: Liu Jinlu , Li Jun , Li Yingjie , Li Hui , Yang Hongwei , Liu Gonghui 
Published: August 2024

ABSTRACT:
Casing force and deformation during MPC (managed pressure cementing) waiting setting stage in deep and ultra-deep wells significantly impacts wellbore integrity. To accurately analyze casing force, the cement hydration and heat release process during waiting setting of cement is initially considered, followed by the establishment of a prediction model for Casing-Fluid-Formation temperature field. Subsequently, a diagram illustrating casing stress is constructed. Based on the predicted temperature field results, the comprehensive influence of temperature on axial force of the casing, column pressure of cement, and casing gelling suspension force are taken into account to establish a prediction model for casing force during cement stone hardening. Using hook load data from a well A in Sichuan Basin as an example, the model is verified with a prediction error of less than 5%. Key parameters during the cementing process are analyzed. The findings indicate that the casing temperature field initially decreases before increasing and then decreasing again over time. Due to changes in the temperature field, both fluid column pressure and suspension force of the casing undergo constant variations while the cement is hydrated. When casings experience stresses exceeding their strength limits, plastic deformation occurs which compromises wellbore integrity. The results of this study can provide theoretical guidance for wellbore integrity during MPC waiting setting stage.

1. INTRODUCTION
With the growth of human demand for oil and gas resources, oil and gas extraction is gradually developing in the direction of deep and ultra-deep wells (Liu, et al., 2023). The harsh natural conditions as well as low reserves and hard-to-explore oil and gas reservoirs require low-cost, efficient and safe cementing technologies. Meanwhile, with the increase of well depth, the construction process is more and more facing the problems of HPHT (high temperature and high pressure), narrow density window, narrowing of wellbore flow channel, long bare hole section, et al. The increasingly complex construction conditions bring new challenges to the cementing (Xu, et al., 2019). For cementing in complex formations, overflow is easily induced by pressure, in addition. If the pressure is increased excessively during the construction, it may also lead to downhole leakage, all of which may result in failure of cementing and bring very big hidden dangers to the cementing construction. As the cementing process is complicated and involves many links, the MPC (managed pressure cementing) technology has become extremely urgent (Rostami, et al., 2017; Wilson, et al., 2018). The research on MPC technology will greatly reduce the cost of cementing, improve the quality of cementing, reduce the occurrence of accidents, and ultimately further improve the level of oil and gas drilling and completion (Thibodeaux, et al., 2018; Teoh, et al., 2019).
Study on Wellbore Stability of the Intrusions in Manshen Block, Tarim Basin
Authors: Tang Bin , You Zhi , Gao Haiyang , Liu Sen , Xiao Guilin , Li Hongda , Lu Yunhu 
Published: August 2024

ABSTRACT:
A set of intrusions is developed in the deep Ordovician in Western China. However, the complex coexistence of losses, collapse and jamming during drilling seriously restricts the exploration and development of deep oil and gas resources. Aiming to solve the problem, this article first conducted geophysical and engineering characteristics analysis on the drilled wells that encountered the intrusions in the field, then carried out the physical and mechanical experiment with the intrusions and performed numerical simulation of the intrusions, to clarify the wellbore instability mechanism and controlling countermeasures of the intrusions in the block. The results of the experiment show that the existence of microfractures significantly reduces the overall strength of the intrusions, and provides a channel for drilling fluid intrusions. The results of the numerical simulation show the existence of the weak plane effect of microcracks plays a main role in controlling the wellbore instability of the intrusions. For the intrusions with high degree of breakage, within the safe drilling fluid density range, the impact of density changes has little influence on the wellbore instability, while the plugging property has great influence on the wellbore stability. The research achievements are helpful to guide similar strata to improve wellbore instability.

1. INTRODUCTION
As global energy consumption continues to increase, achieving efficient development of deep and ultra-deep resources has become an important goal to continue conventional oil and gas resources and increase oil and gas production. However, according to statistics, the phenomenon of wellbore instability widely exists in the exploration and development of deep and ultra-deep resources in major oil and gas fields around the world. It is currently the most important complex problem plaguing the drilling engineering community (Chen et al., 2008; Jin and Chen, 2012). The Manshen block studied in this article is located in the hinterland of the Taklimakan Desert and in the Aman transition zone of the northern depression of the Tarim Basin. It has abundant oil and gas reserves and huge development prospects. The strata below the Ordovician in this block are affected by diabase intrusions. During the drilling process, losses and collapse are prone to occur, resulting in frequent downhole obstructions, which seriously restricts safe and efficient drilling.
A Numerical Solution to the Flow-Induced Vibration of a Hanging String in a Storage Cavern
Authors: Chieslar J. D. 
Published: August 2024

ABSTRACT:
A hanging string is the center pipe or tube in a storage cavern. It is situated inside of a cemented casing and, in conjunction with the cemented casing, is used to move product (crude oil, propane, natural gas, etc.) into and out from the storage cavern. When the injected fluid exits the hanging string, it exerts a back-pressure, causing the string to vibrate. Above a certain injection flow rate, the vibration becomes unstable. Before this condition, however, the string may bend and even break due to fatigue. Recently a field test (Reitze, A. 2019) was conducted at four different injection rates to assess the tendency for the hanging string to vibrate. This provided the opportunity to validate closed form solutions (Ratigan, J. 2004, 2017). The purpose of this communication is to provide a numerical solution to this problem. The numerical model produced results within the minimum and maximum vibration amplitudes recorded in the field test, at all four flow rates. Furthermore the numerical solution affords the opportunity to capture effects not normally addressed in closed form solutions.

1. INTRODUCTION
As early as 2004 SMRI (Solution Mining Research Institute) (Ratigan, J. 2004) has taken an interest in the vibrations of hanging strings in storage caverns by virtue of it's funding research into this phenomenon. A cavern operator would naturally prefer to maximize the flow rate while avoiding any possible damage. Consequently there exists a motivation to definitively characterize this phenomenon. While it may be most common that the hanging string is a 10.75 inch (0.273 meter) diameter pipe, the length of the string beyond the cemented casing as well as the fluids involved would certainly impact the flow rate at which instability develops. To this end SMRI recently funded a field test (Reitze, A. 2019) in which a hanging string was instrumented and motions were measured at four different flow rates. Prior to this McGill University undertook research into this phenomenon which involved the development of analytical models as well as bench-scale testing. This work may be summarized in the thesis of S. L. Minas (Minas, S.L. 2017).
Sonar Surveys/Nurb-Surfaces/Adaptive, Body-Fitted Meshing for Large-Scale Modeling of Multiple Solution Mines
Authors: Chieslar J. D. 
Published: August 2024

ABSTRACT:
An adaptive meshing technique is detailed which is suitable for large scale finite element modeling of solution mines. The resulting meshes of "bricks" are fully compatible (portable), that is no hanging nodes result, requiring multi-point constraints to satisfy continuity. The procedure begins with sonar surveys and a corrective process is undertaken to make the resulting geometries suitable for meshing. Oftentimes the sonar surveys have irregularities, not to mention excessive detail which makes meshing cumbersome and time-consuming. Solution mines used for waste disposal are often incomplete since the sonar doesn't penetrate the waste. Solid modeling techniques are used to ‘plug’ holes in incomplete surveys. Non-uniform rational b-splines are subsequently fit to the surfaces of the pre-processed solution mines and a subsequent discretization is made to create a suitably-coarse description while respecting the mine geometry and volume. The voxel characteristic at the cavern wall is removed, resulting in a mesh, composed entirely of bricks, accurately representing the cavern geometry.

1. INTRODUCTION
Sonar surveys of solution-mined caverns, typically situated in salt domes, once read into a visualization application, may have obvious irregularities, may be incomplete, or may have unnecessarily high resolution for meshing purposes. In order to prepare these geometries for meshing, we shall pre-process these, first by fitting a b-spline surface to each, then discretize each to a resolution that both respects the geometry and admits an efficient interrogation for mesh generation purposes.
Once pre-processed a solid model is constructed using the discretized caverns. This model defines not only the modeling domain, but also includes geometries identifying locations for refining the mesh (adapting) and also parses the domain to isolate areas of particular importance for post-processing. Certain post-processing techniques may become excessively slow for interaction and interrogation purposes, if these techniques are extended throughout the modeling domain.
For salt domes hosting multiple caverns, interest has increased in assessing the influence of caverns on each other, particularly when considering that cavern volumes generally increase over time. This is due largely to difficulties in maintaining a fully saturated brine in caverns that are frequently filled and emptied. This ongoing dissolution generally overcomes the natural tendency for the caverns to close due to creep. Adaptive meshing is vital when multiple caverns are considered in a single simulation exercise. This allows suitably ‘small’ elements for cavern walls while simultaneously allowing increasingly larger elements beyond.
Drilling Design and Optimization Technology for Ultra Deep Wells in Tarim Oilfield: A Case Study of Well Take-1, the Deepest Well in Asia
Authors: ChunSheng Wang , ShaoBo Feng , Zhi Zhang , Bo Zhou , XiaoLiang Wang , XiaoGang Lv , JinLong Liu , Bao Zhou 
Published: August 2024

ABSTRACT:
The Tarim Basin is a Precambrian superimposed composite basin. The main source rocks are characterized by ultra-deep and ancient characteristics. In 2023, based on the dual goals of oil and gas discovery and scientific exploration, Tarim Oilfield proposed the deepest exploration target in China named Take-1, to explore deeper carbonate oil and gas reservoirs under the Fuman Oilfield, with a designed vertical depth of 11,100 meters. In order to achieve drilling goals safely and efficiently, pioneering work has been done in drilling design. The drilling design is based on comprehensive geological engineering research. The design of the upper casing reaches the deepest depth in the area, and engineering technical measures are adopted to achieve the drilling of multiple sets of strata. The force of wellhead tools on ultra-long and overweight casing is simulated and calculated to avoid the casing entering the plastic deformation state during the running process. Hydraulic parameters and vibration effects shall be fully considered during the design of drilling tool assembly to realize safe drilling. The research and field implementation progress show that the key technology of the drilling design of Take-1 can solve the series of drilling difficulties faced and achieve the goal of the 10,000-meter drilling project.

1. INTRODUCTION
In 2023, the Tarim Oilfield proposed the deepest exploration target in China, with the well number Take-1. One of the purposes is to explore the deeper carbonate reservoirs under the Fuman oil field. The design vertical depth is 11,100 meters, and drilling commenced on May 30, 2023, reaching a depth of 10,000 meters by March 4, 2024.
At present, there is only one well with a vertical depth of over 10,000 meters drilled on land worldwide, which is the SG-3 well drilled by the former Soviet Union in 1989. The completed drilling depth is 12,262 meters (Claesson et al. (2000)). The well was drilled in four sections with a 36-inch pilot hole and an 8 1/2-inch borehole, and took 23 years to complete. The Tiber well, which was completed at a depth of over 10,000 meters in the deepwater basin of the Gulf of Mexico, USA, was drilled to a depth of 10,685 meters (1,259 meters of water depth) using a seven-opening structure (Naranjo, J. C. et al. (2011)). In October 2022, Abu Dhabi National Oil Company of the UAE set a new record for the world's deepest well in the UZ-688 well on the artificial island of the Upper Zakum field, which was completed at a depth of 15,240 meters in a horizontal well (El Sabeh, K.et al.(2023)).
Surrogate-Based Hydraulic Fracture Propagation Prediction Using Deep Neural Network Proxy
Authors: Li Fan , Zhang Yayun , Xiao Cong 
Published: August 2024

ABSTRACT:
Reliable prediction and uncertainty quantification of hydraulic fracture propagation behavior are crucial aspects of unconventional reservoir development, however, their implementations are largely restricted by the huge computational cost of the high-fidelity model simulations. We present a deep autoencoder neural network proxy workflow that allows us to rapidly visualize subsurface fracture morphology (e.g., fracture width, fracture height and fracture length) given pumping schedule and rock properties (e.g., Poisson ratio, Young module, leakage coefficient, etc). Nevertheless, the training process becomes inefficient due to the large output dimensionality. To overcome this issue, an autoencoder network is initially employed to uncover lower-dimensional features that effectively represent high-dimensional fracture morphology images. In our methodology, the regression model is trained to forecast lower-dimensional features instead of directly constructing original fracture image. During the prediction phase, the trained regression model initially predicts the latent variables based on wellhead pumping data, formation characteristics, and rock geomechanic properties. Subsequently, these latent variables are utilized as inputs for the trained decoder to generate fracture morphology images. In addition, a fast self-developed full-physics fracturing simulator is used to efficiently simulate a large set of training samples related to the fracture morphology. Some preliminary results based on a simple illustrative example, i.e., single-fracture propagation, are used to demonstrate the accuracy and efficiency proposed approach. The proposed deep-learning-based visualizations model should be a fast emulator for quantitative characterization and monitoring of hydraulic fracturing stimulation. Further research is required to verify its applicability to field-scale reservoir models with complex fracture network.

1 INTRODUCTION
Horizontal wells hydraulic fracturing is a key technology for unconventional oil and gas development (Daneshy et al, 2011; Barati et al, 2014). In order to improve the degree of reserve utilization, North American oil companies are continuously exploring volume transformation technologies to reduce well spacing and fracture spacing. Onsite fiber-optic temperature monitoring and acoustic monitoring indicate that in the case of small spacing renovation, there are issues such as uneven liquid injection in multiple clusters of cracks, and the proportion of liquid injection in each cluster is closely related to factors such as perforation parameters and stress distribution in each cluster (Wheaton et al, 2016). To improve the balanced expansion of multi cluster fractures and optimize the design of multi cluster fracturing schemes, it is urgently necessary to establish an efficient simulation method for multi fracture propagation coupled with wellbore perforation fracture (Chen et al, 2022, 2022).
Helium Gas Release by Rocks Undergoing Crushing
Authors: Kibikas W. M. , Paul M. J. , Wilson J. E. , Kruichak-Duhigg J. N. , Broome S. T. 
Published: August 2024

ABSTRACT:
Geogenic gases often reside in intergranular pore space, fluid inclusions, and within mineral grains. In particular, helium-4 (4He) is generated by alpha decay of uranium and thorium in rocks. The emitted 4He nuclei can be trapped in the rock matrix or in fluid inclusions. Recent work has shown that releases of helium occur during plastic deformation of crustal rocks above atmospheric concentrations that are detectable in the field. However, it is unclear how rock type and deformation modalities affect the cumulative gas released. This work seeks to address how different deformation modalities observed in several rock types affect release of helium. Axial compression tests with granite, rhyolite, tuff, dolostone, and sandstone - under vacuum conditions - were conducted to measure the transient release of helium from each sample during crushing. It was found that, when crushed up to 97500 N, each rock type released helium at a rate quantifiable using a helium mass spectrometer leak detector. For plutonic rock like granite, helium flow rate spikes with the application of force as the samples elastically deform until fracture, then decays slowly until grain breakdown comminution begins to occur. Both the rhyolite and tuff do not experience such large spikes in helium flow rate, with the rhyolites fracturing at much lower force and the tuffs compacting instead of fracturing due to their high porosity. Both rhyolite and tuff instead experience a lesser but steady helium release as they are crushed. The cumulative helium release for the volcanic tuffs varies as much as two orders of magnitude but is fairly consistent for the denser rhyolite and granite tested. The results indicate that there is a large degassing of helium as rocks are elastically and inelastically deformed prior to fracturing. For more porous and less brittle rocks, the cumulative release will depend more on the degree of deformation applied. These results are compared with known U/Th radioisotopes in the rocks to relate the trapped helium as either produced in the rock or from secondary migration of 4He.
Sensitivity Analysis of a Dynamic Subsidence Prediction Model for Longwall Extraction
Authors: Maldonado E. , Benitez J. D. Romero , Agioutantis Z. 
Published: August 2024

ABSTRACT:
Surface ground deformations due to mining are dynamic in nature and depend, among others, on the rate of mining. There are many formulations that can calculate and predict ground deformation due to mining. The majority of these models can accurately predict final deformations, i.e., maximum deformation values at specific surface points. In many instances, dynamic deformation values need to be considered, especially when undermining surface structures that are sensitive to subsidence, differential displacements, and/or tilt. This paper discusses subsidence development (dynamic subsidence) over a longwall excavation in the eastern US, which was recently completed. Measurements include x,y,z coordinates of a number of points (stations) over the longwall panel, which were monitored over a period of time while mining the panel. Dynamic subsidence was modeled for each of these surface points using an empirical formulation based on the influence function method as implemented in the Surface Deformation Prediction System (SDPS) package. Results show that the location of each surface point with respect to panel boundaries affects the calculation of dynamic subsidence values. A sensitivity analysis was completed for some of the parameters that influence dynamic subsidence calculations. These parameters include the edge effect offset and the time factor.

1. INTRODUCTION
Full extraction methods for underground coal mining, such as longwall mining, can result in movements of the surrounding rock layers. When such movements propagate to the surface, surface subsidence may occur. As mining activities progress, movements induced by mining extend from the coal strata through the overburden to the surface (Agioutantis et al., 2018). The study of subsidence in coal mining regions started in Europe during the mid-20th century (Bauer, 2008). Since then, a number of scientific publications regarding subsidence prediction methods have been completed. Currently, a number of final deformation prediction methods are available to model longwall panels and can be applied to different cases with variable features (Whittaker et al., 1989; Kratzsch, 1983).