scholarly journals How to Seal Hydraulic Fracturing Boreholes in the Large-Size HDR Rocks under HTHP Conditions

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 5) ◽  
Author(s):  
Zhang Hongwei ◽  
Wan Zhijun ◽  
Yixin Zhao ◽  
Zhou Changbing ◽  
Zhu Chuanqi ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Laboratory Test ◽  
Heat Production ◽  
Injection Pressure ◽  
Large Size ◽  
High Injection ◽  
High Injection Pressure ◽  
Sealing Failure

Abstract The hydraulic fracturing (HF) is a key technique to enhance the permeability and heat production of hot-dry-rock (HDR) geothermal reservoirs. Normally, laboratory HF tests should be preconducted to understand the HF characteristics of HDR samples. However, in the laboratory test, sealing failure between boreholes and injection pipes always limits the experimental efficiency and data accuracy, especially for the HF tests under high-temperature and high-pressure (HTHP) conditions. Traditional sealing methods, such as rubber and cement sealing, are easy to be failed because of their poor load and/or thermal bear performance under HTHP conditions. Therefore, in this study, we proposed a novel HTHP seal by using wedge-buckled copper components and steel rings. The sealing efficiency was verified by successfully conducting the HF tests of HDR rocks with a dimension of φ200×400 mm under various high temperatures ranging from 100°C to 400°C. As expected, the unfavorable factors such as HTHP and high injection pressure could be turned into favorable ones during the introduced seal method. By this investigation, we expect to provide some sealing solutions for researchers when conducting HF tests under HTHP environments.

The Effect of Ambient Gas Temperature and Density on the Development and Wall Impingement of High-Injection-Pressure Diesel Fuel Sprays

1993 ◽  
Vol 115 (4) ◽  
pp. 777-780 ◽  
Author(s):  
Gong Yunyi ◽  
Liang Xuanming
Keyword(s):  
High Pressure ◽  
Ambient Temperature ◽  
Diesel Fuel ◽  
Injection Pressure ◽  
Spray Angle ◽  
Gas Temperature ◽  
High Injection ◽  
High Injection Pressure ◽  
Wall Impingement ◽  
Ambient Gas

An investigation of the effect of ambient gas temperature and density on diesel fuel spray penetration, spray angle, and wall impingement at an injection pressure of 75–134 MPa was conducted in a constant-volume bomb with a reconstructed Cummins PT fuel system by using a high-speed photographic technique. The results show that penetration does not increase monotonically with injection pressure, and ambient temperature has more effect on a high-pressure spray than on those with conventional pressures. With the high temperature, the penetration of a high injection pressure spray is reduced a bit, while the spray angle increases obviously. When the high-pressure spray impinges on a wall at ordinary temperature, the rebounding droplets can hardly be seen, but at higher wall temperature, a cloud of dense spray will be observed near the wall, and sometimes a vapor layer will be formed between the spray and the wall. Based on experimental results, an empirical formula considering the effects of both the ambient temperature and injection pressure is presented.

Deformation of nozzle, needle, and control plunger of solenoid fuel injector under high injection pressure

2018 ◽  
Vol 233 (7) ◽  
pp. 1767-1782 ◽  
Author(s):  
Dong-wei Wu ◽  
Bai-gang Sun ◽  
Dan Xu
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Geometric Parameters ◽  
Structural Deformation ◽  
Fuel Injector ◽  
Longitudinal Deformation ◽  
High Injection ◽  
High Injection Pressure ◽  
And Control

Future diesel engines require the use of solenoid fuel injection system with the ultra-high pressure of more than 2000 bars. The nozzle, needle, and control plunger of the solenoid injector deform under high pressure. This deformation affects the movement characteristics of the needle, thereby influencing the precise control of fuel injection. A test rig is set up to investigate the structural deformation and influencing factors of the solenoid injector under high pressure. The structural deformation of nozzle, needle, and control plunger under different pressures can be obtained by measuring the displacement of the upper end of the control plunger in the axial direction. The experimental longitudinal deformation of nozzle, needle, and control plunger of the solenoid injector, which was selected for the study, reaches 0.109 mm under the pressure of 1600 bars. This value is close to 40% of the maximum needle lift, which is 0.3 mm. Thus, the deformation can no longer be ignored. In view of the solenoid injector deformation under high injection pressure, a three-dimensional calculation model is established. The calculated results are compared with the experimental data. The calculation total longitudinal deformation of nozzle, needle, control plunger, and contact surface reaches 0.238 mm under the pressure of 2500 bars. The structure deformation of solenoid injector with different materials or geometric parameters is calculated under the pressure of 100–2500 bars. The deformation with new materials is 0.198 mm and the deformation with new geometric parameters is 0.0333 mm under the pressure of 2500 bar. These calculations show that the use of shorter control plungers, shorter needles, and larger wall thickness nozzles can effectively reduce injector deformation under high pressure. The results of the study can provide guidance on injector design, which can work with high injection pressure and much accurate injection.

High Pressure, High Temperature Bioreactors as a Biocide Selection Tool for Hydraulically Fractured Reservoirs

2021 ◽  
Author(s):  
Joseph Ferrar ◽  
Philip Maun ◽  
Kenneth Wunch ◽  
Joseph Moore ◽  
Jana Rajan ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Fractured Reservoirs ◽  
Field Trials ◽  
Detectable Level ◽  
Program Optimization ◽  
Microbial Counts ◽  
Selection Tool ◽  
High Pressure High Temperature

Abstract We report the design, operation and biogenic souring data from a first-of-its kind suite of High Pressure, High Temperature (HPHT) Bioreactors for hydraulically fractured shale reservoirs. These bioreactors vet the ability of microbial control technologies, such as biocides, to prevent the onset of microbial contamination and reservoir souring at larger experimental volumes and higher pressures and temperatures than have been previously possible outside of field trials. The bioreactors were charged with proppant, crushed Permian shale, and sterile simulated fracturing fluids (SSFF). Subsets of bioreactors were charged with SSFF dosed with either no biocide, tributyl tetradecyl phosphonium chloride (TTPC, a cationic surface-active biocide), or 4,4-dimethyloxazolidine (DMO, a preservative biocide). The bioreactors were shut in under 1,000-2,500 psi and elevated temperatures for up to fifteen weeks; hydrogen sulfide (H2S) and microbial counts were measured approximately once per week, and additional microbes were introduced after weeks three and five. Across two separate studies, the bioreactors containing no biocide soured within the first week of shut-in and H2S concentrations increased rapidly beyond the maximum detectable level (343 ppm) within the first three to six weeks of shut-in. In the first study, the bioreactors treated with TTPC soured within two weeks of shut-in (prior to the first addition of fresh microbes), and H2S concentrations increased rapidly to nearly 200 ppm H2S within the first six weeks of shut-in and beyond the maximum detectable level after fifteen weeks of shut-in. The bioreactors containing DMO did not sour during either study until at least the first addition of fresh microbes, and higher levels of the preservative biocide continued to prevent the biogenic formation of H2S even during and after the addition of fresh microbes. Microbial counts correlate with the H2S readings across all bioreactor treatments. The differentiation in antimicrobial activity afforded by the different types of biocide treatments validates the use of these simulated laboratory reservoirs as a biocide selection tool. This first-of-its-kind suite of HPHT Bioreactors for hydraulic fracturing provides the most advanced biocide selection tool developed for the hydraulic fracturing industry to date. The bioreactors will guide completions and stimulation engineers in biocide program optimization under reservoir-relevant conditions prior to beginning lengthy and expensive field trials.

scholarly journals Experimental and Numerical Evaluation of Hydraulic Fracturing under High Temperature and Embedded Fractures in Large Concrete Samples

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3171
Author(s):  
Liangliang Guo ◽  
Zihong Wang ◽  
Yanjun Zhang ◽  
Zhichao Wang ◽  
Haiyang Jiang
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Laboratory Test ◽  
High Temperatures ◽  
Large Scale ◽  
Hydraulic Fractures ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracture Density

In order to study the mechanism of hydraulic fracturing in enhanced geothermal systems, we analyzed the influence of high temperatures and embedded fractures on the initiation and propagation of hydraulic fractures using a laboratory test and numerical simulation. The analysis was conducted via large-scale true triaxial hydraulic fracturing tests with acoustic emission monitoring. Moreover, we discussed and established the elastic-plastic criterion of hydraulic fracturing initiation. The corresponding fracturing procedure was designed and embedded into the FLAC3D software. Then, a numerical simulation was conducted and compared with the laboratory test to verify the accuracy of the fracturing procedure. The influence of high temperatures on hydraulic fracturing presented the following features. First, multi-fractures were created, especially in the near-well region. Second, fracturing pressure, extension pressure, and fracture flow resistance became larger than those at room temperature. 3D acoustic fracturing emission results indicated that the influence of the spatial distribution pattern of embedded fractures on hydraulic fracturing direction was larger than that of triaxial stress. Furthermore, the fracturing and extension pressures decreased with the increase of embedded fracture density. For hydraulic fracturing in a high temperature reservoir, a plastic zone was generated near the borehole, and this zone increased as the injection pressure increased until the well wall failed.

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