bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation Study on Fracture Propagation Induced Flooding in Tight Reservoirs
Authors: Peng Yan , Lv Peihong , Wei Shengjie 
Published: September 2023

ABSTRACT
Tight reservoirs are important resources all over the world, but its recovery rate is low. The common enhanced recovery technique is water flooding. If the fracture propagation is induced during water flooding, the recovery rate of tight reservoirs will increase. However, the quick fracture propagation can connect injection wells and production wells, and then induce the sudden water influx, therefore, the injection pressure should be carefully controlled. In this study, we established numerical simulation model that considered the impacts of two-phase fluid flow through tight reservoirs, rock deformation, water-rock interactions and fracture propagation. Using this model, the propagation mechanism of fracture induced by water flooding was discovered and then factors controlling fracture propagation were discussed. The main conclusions are (1) the heterogeneity magnitudes of rock properties, such as Young's modulus, are decreased by water flooding. The rock property is changed by the long term of water-rock interactions and its magnitude depends on water amount. This heterogeneity of rock property further causes the stress redistribution and stress decrease around fracture tip. The decrease magnitude of stress can be up to 26.5%. (2) The impact of water-rock interaction on mechanical rock properties affected the propagation magnitude of WIF. The maximum magnitude of WIF propagation length can reach 25.7% of initial WIF length. (3) To avoid WIF propagates rapidly, the injection pressure needs to be controlled carefully. It is because that water-rock interaction makes critical injection pressure decreases, maximum decrease magnitude of critical injection pressure can reach 26.5% of the minimum horizontal stress.

INTRODUCTION
Tight reservoirs are widely distributed in China, such as Permian in Junggar Basin, Triassic in Ordos Basin, and Jurassic in Sichuan Basin (Zhu et al., 2019. Wang et al., 2007. Gao, 2009.), with abundant reserves and great oil production potential. At present, the most effective oil recovery technology is the water flooding. During the Oil production period, if fracture propagation occurred, it may promote the recovery of tight reservoirs. However, if the fracture propagates too fast, it is very likely to cause the water-induced fracture (WIF) to connect with the production fracture to form a flood channel, thereby reducing the development efficiency of tight reservoirs. Therefore, exploring the propagation mechanism and influencing factors of WIFs to improve the recovery rate of tight reservoirs is of great significance.
Rheological and Mechanical Properties of Cement Grouts for Geothermal Well Cementation with Seashell Powder as Full Metakaolin Replacement
Authors: Wilson A. , Grégoire D. 
Published: September 2023

ABSTRACT
The different conditions associated with geothermal wells call for cement grouts that are lightweight, flexible and same time, possess good mechanical properties that can improve well integrity. This paper presents an experimental study of formulating lightweight and resilient cement grouts by a full replacement of metakaolin with crushed seashell wastes in a classical slurry formulation. Seashell powders made from Crassostrea gigas (Oyster), Pinctada maxima, Pecten maximus (scallop) and Crepidula fornicata were used to formulate the low-density slurries of approximately 1.2 specific gravities. Without using any chemical additives, the rheological behavior of the slurries, thermal properties and the mechanical properties of the set cements containing seashell powders were examined in comparison with classical samples containing metakaolin. The results showed an improved rheological behaviour in the context of geothermal well applications. The mechanical property investigations also revealed an improvement in elastic and flexural properties which may improve the global well integrity.

INTRODUCTION
The net-zero decarbonisation of the global energy sector will require an increase in the exploitation of renewable energy resources like geothermal energy. Geothermal energy is estimated to be capable of producing up to 8.3% of the world's electricity (WEC, 2019). Due to the high cost involved in the building and repair of geothermal wells, it is important to design them capable of producing energy for up to about 30 years. Cements used for zonal isolation in geothermal wells face conditions of high temperature and pressure (HTHP) that may affect the well integrity.
A greater number of cement failures are reported to have been due to tensile loading rather than compressive (Lullo and Phil, 2000). This makes it important to optimize flexibility of the cement sheath during slurry design. Low density cements with lower Young's modulus are more flexible and are capable of providing higher expansions to accommodate the cyclic casing expansions due to temperature variations (Sugden et al., 2012). Another importance of lowering slurry density is in the avoidance of loss circulation which could occur if the hydrostatic pressure of the slurry exceeds the fracture strength of the surrounding formation (Sugama, 2007). Some methods of achieving low density slurries include foamed cement technologies (Harms and Febus, 1985; Sugama, 2007) and hollow microspheres (Abdullah et al., 2013).
Chemical Treatment for Sustainable Acid Fracture Conductivity of Weak Carbonates
Authors: Desouky M. , Aljawad M. S. , Amao A. , AlShehri D. A. , AlTammar M. J. , Alruwaili K. M. 
Published: September 2023

ABSTRACT
Acid fracturing is an essential stimulation technology to increase the production of carbonate reservoirs. However, acid usually softens the rock, and the stability of the fracture hydraulic conductivity is hardly maintained. Therefore, rock strength after an acid treatment is crucial in controlling the emerging hydraulic conductivity. Consolidation agents like diammonium phosphate (DAP) could enhance the mechanical properties of damaged or weak carbonate rocks. This study investigates the DAP consolidation effect on weak carbonate fracture hydraulic conductivity. Weak Austin chalk samples were soaked in 1 M DAP for 72 hrs. under high pressure and temperature. The surface hardness of weak Austin chalk samples was evaluated nondestructively using impulse hammering. The sample's surface hardness was greatly improved upon the DAP treatment. The treated samples’ hydraulic fracture conductivity and compaction were measured and compared with similar untreated samples. The treated samples exhibited higher and sustained hydraulic conductivity and less compaction under higher stress. The proposed solution could be particularly useful in soft carbonate formations, where induced acid softening is a common problem. Boosting the fracture surface hardness with DAP can improve the efficiency of the acid stimulation process and increase the amount of hydrocarbons that can be extracted.

INTRODUCTION
While acid fracturing manifests itself as one of the most deployed stimulation methods in carbonate reservoirs, its success is limited by the carbonate strength after the operation. The asperities that keep the fracture open are more vulnerable to failure because acidizing decreases the compressive strength of the carbonate (Gong et al., 1999). Likewise, (Nierode & Kruk, 1973) in Equations 1&2 related the hydraulic conductivity (kfwi) of the fracture to the rock embedment strength (SRE), e.g., the lower the embedment strength, the lower the hydraulic conductivity. Moreover, the rock embedment strength determines the rate at which the conductivity falls under stress (σC) (Gomaa & Nasr-El-Din, 2009). Also, soft carbonates like chalk exhibit more time-dependent deformation (creep) than harder carbonates like dolomite (Abass et al., 2006).
(Equation)
(Equation)
In carbonate gas wells post-acid fracturing jobs, a severe production loss of more than 60% within 6 months was reported (Bartko et al., 2003). The reasons behind the sharp decline should be understood before considering restimulation jobs which are not usually successful (Abass et al., 2006). However, the best scenario would be to have a sustainable acid fracture at the first trial.
Analysis of the Influence of Deep/Ultra-Deep Rock Mechanical Properties Difference on Rock Breaking Efficiency of PDC Bit and Research on Cutter Shape Optimization-Taking Shunbei Oilfield as an Example
Authors: Zhuoxin Dong , Hui Zhang , Kerou Liu , Yufei Chen 
Published: September 2023

ABSTRACT
Polycrystalline diamond compact (PDC) is widely used in petroleum engineering drilling due to its strong wear resistance, fast penetration rate and high bit footage. But with the increase of formation depth, the formation rocks become dense, high strength and difficult to be destroyed under the action of geostress, which makes the drilling speed in deep/ultra-deep layers slow. In this paper, the characteristic law of rock strength characteristics changing with well depth is analyzed, and the numerical simulation model of single cutter rock breaking based on the Cohesive element is established. According to the numerical simulation results and the change of confining pressure with depth in Shunbei Oilfield, the suitable depth range of each cutters is recommended by layers. The results show that the rock strength characteristics gradually increase with the depth, and the impact on the rock breaking of the cutting teeth is mainly the increase of the weight on bit and the cutting force. By analyzing the numerical simulation results, the circular cutter is suitable for shallow formation, the curved cutter is suitable for medium and deep well section, and the triangular cutter is suitable for ultra deep formation.

INTRODUCTION
Oil and natural gas are the main raw materials for obtaining energy in the world today. With the improvement of the development level of oil and natural gas, the depth of recoverable oil reservoirs is getting deeper and deeper, and the depth and number of deep/ultra-deep wells are also increasing. (Wang HG, Huang HC, Bi WX, et al. 2021). For these deep/ultra-deep wells, the traditional drilling methods cannot effectively drill, and it is difficult to meet the needs of rapid deployment of well patterns in the oilfield. (Tian S, Huang Z, Niu J, et al. 2009). Therefore, it is quite necessary to carry out the research on rock breaking law of PDC cutters for deep/ultra-deep layers.
A Comparison of Empirically Estimated Rock Mass Modulus Values at a Soft-Rock Site
Authors: Lindenbach E. J. , Bearce R. G. , Foran J. F. 
Published: September 2023

ABSTRACT
The rock mass modulus, or deformation modulus, of an underlying rock mass is an important input variable for any load-deformation analysis of a foundation, such as numeric modeling of a dam. The deformation modulus can be determined empirically using a variety of different relationships that incorporate parameters readily determined from geologic logs and laboratory testing. Relying on one value can be fraught, though, as a low rock mass modulus can improve damping of seismic waves while a high rock mass modulus can increase static stability. Therefore, developing a realistic range of values is of paramount importance. In this paper, a probabilistic approach incorporating distributions for input parameters and ten empirical relationships was used to determine a range of anticipated foundation rock mass modulus values for a proposed spillway, thereby allowing for a range of model outcomes to be simulated. The analysis also found that the relationships to determine rock mass modulus that do not incorporate the elastic modulus as determined during laboratory testing all produced significantly higher rock mass modulus values than those that incorporated the laboratory data; relationships using only RQD and/or RMR appear to break down where the rock mass is relatively fracture free, but the intact rock is soft, as is the case for this site.

INTRODUCTION
Accurately modeling the response of a structure to static or seismic loads is of paramount importance when evaluating critical infrastructure such as dams. Key to the development of accurate models is developing and implementing realistic ranges of input parameters that facilitate the portrayal of a range of possible outcomes. One of the parameters needed in the modeling efforts is the deformation modulus or rock mass modulus. The terms deformation modulus and rock mass modulus are interchangeable, and both imply load-deformations of the rock mass in the elastic and inelastic ranges (Ulusay and Hudson, 2006).
Instrumented Pull Test Results in Grouted Split Sets, and Its Comparison with Non-Grouted Test Results in an Underground Manganese Mine – Corumbá/MS - Brazil
Authors: Silva P. H. , Ribas G. P. , Gontijo A. A. , Saliba G. S. , Lopez J. , Abduani T. C. 
Published: September 2023

ABSTRACT
Rock mass friction stabilizers, commonly called Split Sets, were introduced in the metal mines of the United States and Canada in the early 70s. Split Sets can provide support due to friction between the anchor and the rock surface of the boreholes. As Split Sets are inserted in boreholes with slightly smaller diameter than the diameter of the retainers, the radial force is generated by the compression of the anchor by the drill wall, ensuring its efficiency by friction in this contact interface. In order to increase the maximum load capacity of Split Sets, some mining companies opt for grout injection after the installation of the anchors. The present study presents the results of instrumented pull tests performed in Grouted Split Sets and its comparison with the result of tests performed in Split Sets without the application of cement, in an underground manganese mine. A total of 72 tests were performed in 3 different mine locations, with distinct roof geological characteristics, and the results showed an increase of up to four times the initial strength without the application of grout, considering the best scenario.

INTRODUCTION
Split Sets can provide pressure support due to friction between the anchor and the rock surface of the holes. These were the first types of friction anchors to be used and still are the most widely type operated in underground mining. Split Sets consist of steel tubes sectioned longitudinally, and a steel ring fixed at its lower end, able to apply force to a steel plate that transfers the load to the surface of the excavation. As the Split Sets are inserted in boreholes with slightly smaller diameter than the diameter of the retainers, the radial force is generated by the compression of the tube over the drill wall, ensuring its efficiency by friction in this contact interface (Komurlu and Demir, 2019).
According to Komurlu and Demir (2019) the length of the Anchor is an important parameter for load capacities of support with Split Sets. Load capacity increases with bigger length of anchor. In addition to the length of the Split Set, other parameters have a great influence on the efficiency of this type of anchoring. A factor of great impact on the maximum load supported by the Split Set is the drilling diameter. When anchor of the same characteristics and dimensions are used in different diameters of perforation, we realize that there is a tendency to obtain higher maximum loads using smaller diameters, as shown in figure 1 (Tompson et al. 1999).
The Design of a Downhole Source Tomography Experiment for the Detection of CO2 Plumes in the Subsurface
Authors: McCormack K. L. , Edelman E. , Moodie N. , McPherson B. J. , Paulsson B. , He R. 
Published: September 2023

ABSTRACT
We developed designs to test a new method of detecting supercritical carbon dioxide plumes, which uses a form of reverse vertical seismic profile. The design focuses on two blocks of sandstone, collectively measuring 1m × 1m × 1m, separated by an epoxy seal that simulates the caprock. To simulate leakage through a legacy wellbore, a perforation will be made in the seal at an offset location from an injection well in the center of the sample, and supercritical carbon dioxide will be injected at a rate of 0.01 kg/s into the central well. The experiment is expected to last approximately four hours according to numerical results. While the plume in the reservoir block is likely to be successfully imaged tomographically, there is uncertainty about the ability to image the leak. In addition to the tomography, acoustic emissions will be passively sensed, allowing for an independent assessment of the plume's location.

INTRODUCTION
Detecting and monitoring the migration of a supercritical carbon dioxide plume in a geologic carbon sequestration site, whether in a deep saline or EOR setting, is crucial for the safe use of sequestration technologies. The significance of detection and monitoring is twofold. Firstly, it is essential to determine whether the plume is behaving as expected during site characterization. If the plume migrates in an unexpected direction or to a greater extent due to uncertainties in the injection interval properties, it is critical to assess whether injection operations can continue or if remediation is necessary. Secondly, avoiding faults, subsurface features, and political boundaries is crucial to the success of carbon sequestration operations. For example, in the San Juan Basin CarbonSAFE Phase III project, the injection is attempting to avoid both the Hogback monocline and the Colorado border, which can pose complications. At this stage of the project, simulation is the only method available for plume forecasting. However, when injection commences, collecting data on the plume extent would be immensely valuable.
Productivity Prediction and Production Parameter Optimization of Indirect Fracturing Coalbed Methane Wells
Authors: Cai Xianlu , Wang Zhiming , Huang Tianhao , Li Shengyi 
Published: September 2023

ABSTRACT
The fractures formed in hydraulic fracturing in tectonic coal are relatively short. The indirect fracturing technology simultaneously fractures coal seam and its roof layer, which can significantly increase the fracture extension length. However, compared with conventional coalbed methane fracturing wells, the gas-water flow process in the reservoir becomes more complex. In this paper, a numerical simulation method for productivity prediction of indirect fracturing wells for coalbed methane is developed based on the isothermal adsorption equation, quasi-steady state diffusion equation, and seepage equation. The reliability of the seepage model is verified by the seepage simulation experiment of indirect fracturing wells. The pressure distribution, desorption area distribution, and gas production rate change during coal mining is analyzed. A method of optimizing the bottom hole flowing pressure by stages is developed, which optimizes the bottom hole flowing pressure in water drainage stage, pressure build-up stage, and pressure control stage, respectively. The average relative error between experimental and numerical results is 4.9%. In the production process, the desorption area can be divided into fast desorption area, slow desorption area, and non-desorption area according to the desorption rate. The whole rapid desorption region has a relatively high desorption rate. However, the desorption rate is relatively higher in the region near the roof layer in the slow desorption area. The roof layer provides a high permeability seepage channel for the fluid in the coal seam, and the fluid in the coal seam flows vertically driven by the pore pressure difference between the layers. Fluid flows through the pores of the roof layer and into the fractures. In the stable production stage, the gas production rate of roof layer can reach 40%. This study benefits productivity prediction and analysis of indirect fracturing coalbed methane wells. It can provide theoretical guidance for optimizing the strategy of coalbed methane extraction.
The Effect of the Heavyweight Hematite, Magnetite, and Micromax on Class G Oil Well Cement Properties
Authors: Alvayed Dandi , Mahmoud Ahmed Abdulhamid , Elkatatny Salaheldin , Alafnan Saad 
Published: September 2023

ABSTRACT
A high-density cement slurry is required to adequately balance the high-pressure formations in deep oil wells. The slurry's density could be increased by adding a variety of heavy substances which affect cement slurry and sheath properties. This study investigated the impact of three weighing materials of hematite, magnetite, and micromax on the density fluctuation, compressive strength, and rheology test of Saudi Class G cement slurry of 18 ppg. The results of this work indicated that using a weighting material with large particles can cause vertical heterogeneity, the density variation shows that the hematite cement sample had the largest density variation, with an 8.7% difference between the top and bottom of 4 inches in length sample, led by the magnetite cement sample with a density variation of 7.3%. In the Micromax-weighted sample, the density fluctuation had a vertical variation of 4% and was far less severe than others. Compressive strength measurement shows that the magnetite-weighted cement sample exhibited the highest compressive strength of 65.1 MPa which is 28% greater than the hematite sample. The magnetite slurry had the highest plastic viscosity of 113 cP, followed by 112 cP in the hematite cement. At 56 cP, the plastic viscosity of the micromax-containing heavyweight system was the lowest (50.8 percent less than that of the hematite cement). The smallest yield point was 10 lbf/100 ft2 for the micromax-based cement. Hematite cement had a yield point of 25 lbf/100 ft2, while magnetite-based cement exhibited the highest yield point of 41 lbf/100 ft2. With a 10-sec gel of 14 lbf/100 ft2 and a 10-min gel of 21 lbf/100 ft2, the micromax cement had the lowest gel strength. To avoid problems of segregation and solid abrasion, it is recommended that the particle size of weighing materials be reduced in further investigations.