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You searched for subject:(equilibrium height). Showing records 1 – 3 of 3 total matches.

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Texas A&M University

1. Liu, Songxia. Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window.

Degree: PhD, Petroleum Engineering, 2017, Texas A&M University

Hydraulic fracturing stimulation has become a standard practice to enhance productivity of oil and gas wells in unconventional reservoirs (such as shale, tight sand, coal beds, etc.) previously considered difficult to access. Microseismic (MS) monitoring is routinely used during hydraulic fracturing currently, as a diagnostic technique to assess the created fracture geometry. Despite the technical and economic successes, hydraulic fracturing suffers two uncertainties. First, hydraulic fracture height prediction by equilibrium-height method, significantly affecting fracture treatment design and other issues, is rarely done rigorously, owing to the complexity of the algebra and the reservoir geology. The secondary, unrealistic solution pairs of height tips exist but are not addressed by previous height models. Second, fracture dimensions and stimulated reservoir volume (SRV) implied by MS events are still controversial, because adjacent fracture stimulation stages of horizontal wells severely overlap each other, thus leading to over estimation of future production. In this work, we addressed the first problem by developing a Multilayer Fracture Equilibrium-Height Model (MFEH); the second problem by extracting shut-in period MS data (Closure Window) to describe effective SRV. First, we developed the MFEH model that can rigorously calculate the stress intensity factor (SIF) at two fracture tips and solve the equilibrium height problem in multilayer formation, no matter where the perforations are placed. The MFEH model eliminates those unrealistic secondary solutions by seeking the tip solution pair from the positions nearest the initial fracture. In addition, we introduced a rigorous concept of net pressure base to calculate “apparent” net pressure, by setting fracture toughness of initial fracture tip locations to zero and then calculating the minimum treating pressure to grow the initial fracture. By comparing the MFEH model with previous models, we found the three-layer models are not reliable due to errors in the equations; the modified MW model is correct in the equation to calculate SIF but didn’t address the secondary solution problem; MShale and FracPro have little difference from the MFEH model if layers are normally stressed, although MShale is more reliable than FracPro, but they yield large discrepancy when there are abnormally high or low stress in the adjacent layers of the perforated interval. By studying the tip growth sensitivity to in-situ stress, fracture toughness, and fluid density, we found tip jump is caused by low in-situ stress; tip stability is imposed by large fracture toughness and/or large in-situ stress. Second, we developed an Excel-VBA program to divide the MS events for each fracture stage into three windows: Pad, Proppant, and Closure Windows. The Closure Window includes only MS events during the shut-in period (from the end of slurry pumping), where leakoff and fracture closing are the dominant phenomena. Then we developed a Mathematica program to calculate SRV volume and area.… Advisors/Committee Members: Valkó, Peter P. (advisor), Ayers, Walter B. (committee member), Morita, Nobuo (committee member), Gibson , Richard (committee member).

Subjects/Keywords: fracture height; equilibrium height; microseismic monitor; hydraulic fracturing, SRV

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APA (6th Edition):

Liu, S. (2017). Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/169597

Chicago Manual of Style (16th Edition):

Liu, Songxia. “Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window.” 2017. Doctoral Dissertation, Texas A&M University. Accessed November 28, 2020. http://hdl.handle.net/1969.1/169597.

MLA Handbook (7th Edition):

Liu, Songxia. “Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window.” 2017. Web. 28 Nov 2020.

Vancouver:

Liu S. Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2020 Nov 28]. Available from: http://hdl.handle.net/1969.1/169597.

Council of Science Editors:

Liu S. Hydraulic Fracture Height: Modeling and Evaluation Using Microseismic Closure Window. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/169597


Texas A&M University

2. Pitakbunkate, Termpan. Incorporating Rigorous Height Determination into Unified Fracture Design.

Degree: MS, Petroleum Engineering, 2010, Texas A&M University

Hydraulic fracturing plays an important role in increasing production rate in tight reservoirs. The performance of the reservoir after fracturing can be observed from the productivity index. This parameter is dependent on the fracture geometry; height, length and width. Unified fracture design (UFD) offers a method to determine the fracture dimensions providing the maximum productivity index for a specific proppant amount. Then, in order to achieve the maximum productivity index, the treatment schedules including the amount of liquid and proppant used for each stage must be determined according to the fracture dimensions obtained from the UFD. The proppant number is necessary for determining the fracture geometry using the UFD. This number is used to find the maximum productivity index for a given proppant amount. Then, the dimensionless fracture conductivity index corresponding to the maximum productivity index can be computed. The penetration ration, the fracture length, and the propped fracture width can be computed from the dimensionless fracture conductivity. However, calculating the proppant number used in UFD requires the fracture height as an input. The most convenient way to estimate fracture height to input to the UFD is to assume that the fracture height is restricted by stress contrast between the pay zone and over and under-lying layers. In other words, the fracture height is assumed to be constant, independent of net pressure and equal to the thickness of the layer which has the least minimum principal stress. However, in reality, the fracture may grow out from the target formation and the height of fracture is dependent on the net pressure during the treatment. Therefore, it is necessary to couple determination of the fracture height with determination of the other fracture parameters. In this research, equilibrium height theory is applied to rigorously determine the height of fracture. Solving the problem iteratively, it is possible to incorporate the rigorous fracture height determination into the unified fracture design. Advisors/Committee Members: Valko, Peter P. (advisor), Ehlig-Economics, Christine (committee member), Taliaferro, Steven (committee member).

Subjects/Keywords: hydraulic fracturing; fracture height determination; equilibrium height; unified fracture design; incorporating rigorous height determination into unified fracture design

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Pitakbunkate, T. (2010). Incorporating Rigorous Height Determination into Unified Fracture Design. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8233

Chicago Manual of Style (16th Edition):

Pitakbunkate, Termpan. “Incorporating Rigorous Height Determination into Unified Fracture Design.” 2010. Masters Thesis, Texas A&M University. Accessed November 28, 2020. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8233.

MLA Handbook (7th Edition):

Pitakbunkate, Termpan. “Incorporating Rigorous Height Determination into Unified Fracture Design.” 2010. Web. 28 Nov 2020.

Vancouver:

Pitakbunkate T. Incorporating Rigorous Height Determination into Unified Fracture Design. [Internet] [Masters thesis]. Texas A&M University; 2010. [cited 2020 Nov 28]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8233.

Council of Science Editors:

Pitakbunkate T. Incorporating Rigorous Height Determination into Unified Fracture Design. [Masters Thesis]. Texas A&M University; 2010. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8233

3. Chen, Szu-Yin. The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples.

Degree: MS, Mechanical Engineering, 2015, University of Illinois – Urbana-Champaign

Microporosity (<50μm) in hydroxyapatite (HA) scaffolds is known to improve bone ingrowth. The mechanism for the improvement is thought to be in part due to capillary forces induced by the micropores. The micropore-induced capillary forces can self load cells into the scaffolds. In this study, the effect of micropore size and porosity on capillary forces was investigated. Rectangular shaped HA samples that were either 50% or 60% porous with 5μm, 12μm, 20μm or 50μm pores were fabricated. The samples were characterized by imaging the microstructure, analyzing the composition, measuring the pore size, pore fraction, sample thickness and quantifying the defects inside and outside of the samples. Capillary rise tests were conducted on the samples and fluid height curves were obtained as a function of time. A model was implemented to determine the equilibrium heights and calculate the capillary forces. For 50% porous samples, 5μm samples had the highest equilibrium height and capillary pressure, followed by 12μm, 20μm or 50μm samples. The 60% porous 5μm samples had a faster initial rise, but a lower equilibrium height and capillary pressure than the 50% porous 5μm samples. The 60% porous 50μm samples also had a faster initial rise, a lower equilibrium height and capillary pressure than the 50% porous 50μm samples. Advisors/Committee Members: Johnson Wagoner, Amy (advisor).

Subjects/Keywords: bone scaffold; hydroxyapatite; Microporosity; capillary pressure; equilibrium height

equilibrium height for 50/5, 60/5, 50/12 and 50/20 samples at… …78 Fig. D.4. The equilibrium height for 50/50 and 60/50… …equilibrium height ratio, C/A ratio and A/C ratio of different cut… …37 Table 4.2. The equilibrium height ratio, C/A ratio and… …38 Table 4.3. The equilibrium height of different cut… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Chen, S. (2015). The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples. (Thesis). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/89066

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Chen, Szu-Yin. “The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples.” 2015. Thesis, University of Illinois – Urbana-Champaign. Accessed November 28, 2020. http://hdl.handle.net/2142/89066.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Chen, Szu-Yin. “The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples.” 2015. Web. 28 Nov 2020.

Vancouver:

Chen S. The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples. [Internet] [Thesis]. University of Illinois – Urbana-Champaign; 2015. [cited 2020 Nov 28]. Available from: http://hdl.handle.net/2142/89066.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Chen S. The effect of pore size and porosity on capillary pressure in microporous hydroxyapatite samples. [Thesis]. University of Illinois – Urbana-Champaign; 2015. Available from: http://hdl.handle.net/2142/89066

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.