Impact of Perforation Tunnel Orientation and Length in Horizontal Wellbores on Fracture Initiation Pressure in Maximum Tensile Stress Criterion Model for Tight Gas Fields in the Sultanate of Oman

Failure inception of a deformable sphere loaded by a contacting rigid flat is analyzed separately for perfect slip and for full stick conditions and various material properties of the sphere. Ductile yielding and brittle failure inception of the sphere is identified by the critical interference and associated normal loading as well as the location of the first yield or failure occurrence. The analysis is based on the analytical Hertz solution for frictionless slip condition and on a numerical solution for stick condition. Failure inception is determined by using either the von Mises criterion of plastic yield or the maximum tensile stress criterion of brittle failure.

Download Full-text

Tensile Fracture of Drawn Copper and Mild Steel

Journal of Engineering for Industry ◽

10.1115/1.3185805 ◽

1982 ◽

Vol 104 (1) ◽

pp. 91-96 ◽

Cited By ~ 1

Author(s):

E. G. Thomsen

Keyword(s):

Tensile Stress ◽

Mild Steel ◽

Maximum Tensile Stress ◽

Complete Separation ◽

Fair Agreement ◽

Tensile Fracture ◽

Ofhc Copper ◽

Stress Criterion ◽

Maximum Tensile Stress Criterion ◽

Internal Fracture

Annealed OFHC copper and SAE 1018 steel were reduced by multipass drawing from diameters of 25.4 mm (and smaller) to 11.8 mm. A comparison was made of the experimental draw stresses and those calculated by Sachs’ and Avitzur’s equations and fair agreement exists. The drawn bars were subsequently reduced in diameter by 10 percent in order to provide gage sections and then were pulled in tension to fracture. It was found that in multipass draws some work softening occurs. The oxygen-free copper showed indications that fracture was initiated at the center of the specimen. The internal fracture grew to the near shape of a sphere and separation did not occur until the load had almost decreased to zero. The mild steel apparently also fractured in the center, but complete separation took place immediately after the tensile stress reached its maximum. The fracture theories of Latham and Cockcroft, as well as that of Chen and Kobayashi, were examined and it was found that fair agreement existed. It was also found that for these particular tests, the maximum tensile stress criterion gave more convincing results.

Download Full-text

Analysis of the Tensile Cracking of Rock-Concrete Materials Based on Elasto-Viscoplastic Model

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.4569 ◽

2011 ◽

Vol 243-249 ◽

pp. 4569-4575

Author(s):

Yao Ying Huang ◽

Hong Zheng

Keyword(s):

Tensile Strength ◽

Tensile Stress ◽

Time Course ◽

Maximum Tensile Stress ◽

Viscoplastic Model ◽

Stress Criterion ◽

Plastic Yield ◽

Concrete Materials ◽

Stability Issues ◽

Maximum Tensile Stress Criterion

Suppose there is time course during the cracking and deforming process, the tensile cracking of rock-concrete materials was analyzed by means of elasto-viscoplastic model and its calculation steps were illustrated as well in this paper. The expression of function Φ in elasto-viscoplastic theory was studied; what’s more, it was comparatively analyzed the tensile cracking of rock-concrete materials by elasto-viscoplastic model and the maximum tensile stress criterion respectively. There are some differences comparing with the study of plastic yield by elasto-viscoplastic model, when analyzing the tensile cracking of rock-concrete materials on the basis of elasto-viscoplastic model, the function Φ should be the stress or stress formula of the direction where the principal stress firstly reaches the tensile strength; it is proved by the example analysis that it is feasible to study the tensile cracking of rock-concrete materials by elasto-viscoplastic model and there is no iteration stability issues.

Download Full-text

Integrated Workflow for Selecting Hydraulic Fracture Initiation Points in the Khazzan Giant Tight Gas Field, Sultanate of Oman

10.2118/177939-ms ◽

2015 ◽

Cited By ~ 9

Author(s):

David R. Spain ◽

Raja Naidu ◽

William Dawson ◽

German D. Merletti ◽

Rajeev Kumar ◽

...

Keyword(s):

Hydraulic Fracture ◽

Fracture Initiation ◽

Tight Gas ◽

Sultanate Of Oman ◽

Gas Field

Download Full-text

Mixed Mode Crack Propagation in Iliac Bone

Analele Universitatii Ovidius Constanta - Seria Matematica ◽

10.2478/auom-2021-0034 ◽

2021 ◽

Vol 29 (3) ◽

pp. 67-74

Author(s):

E. Baesu ◽

DM. Iliescu ◽

BV. Radoiu ◽

S. Halichidis

Keyword(s):

Crack Propagation ◽

Critical Stress ◽

Mixed Mode ◽

Crack Path ◽

Maximum Tensile Stress ◽

Iliac Bone ◽

Stress Criterion ◽

Elastic Composite ◽

Anisotropic Elastic ◽

Maximum Tensile Stress Criterion

Abstract Bone is a complex material that can be regarded as an anisotropic elastic composite material. The problem of crack propagation in human bone is analyzed by using a generalization of the maximum tensile stress criterion (MTS). The results concern the critical stress for crack propagation and the direction of the crack path in Iliac bone.

Download Full-text

Hydraulic Fracture Initiation and Propagation Model Provides Theoretical Ground for Hybrid-Type Fracturing Schedules in Unconventional Gas Reservoir in the Sultanate of Oman

10.2118/spe-172950-ms ◽

2015 ◽

Author(s):

Andreas Briner ◽

Alexey Moiseenkov ◽

Romain Prioul ◽

Safdar Abbas ◽

Sergey Nadezhdin ◽

...

Keyword(s):

Hydraulic Fracture ◽

Fracture Initiation ◽

High Viscosity ◽

Propagation Model ◽

Theoretical Ground ◽

Full Potential ◽

Tight Gas ◽

Sultanate Of Oman ◽

Theoretical Understanding ◽

The Impact

Abstract A recent series of tight gas discoveries in the Amin formation of the greater Fahud area represents some of the most exciting exploration success of this decade in the Sultanate of Oman. The structures have been evaluated as containing very significant amounts of gas locked in a challenging deep and hot environment requiring hydraulic fracture stimulation. Since their discoveries, the two primary challenges have been difficult breakdown of the formation and limited proppant placement during stimulation attempts. The early experience in the exploration and appraisal campaigns from 2009 to 2014 has led to fracture designs with conservative proppant amounts that could limit the full potential of the field. Several geomechanical studies have been commissioned in the past to guide completion strategies in well placement, perforation, and fracture stimulation design. The objectives of this study were to model hydraulic fracture initiation and breakdown in the three Amin zones (upper, middle, and lower) to provide some theoretical understanding of the impact of the different parameters on the observed field breakdown pressures. In agreement with field observations, the model showed that lowering the viscosity of the pad has a major impact in lowering the breakdown pressures. Consequently, current best practices include formation breakdown and hydraulic fracture propagation with low-viscosity fluids followed by proppant placement with high-viscosity fluids. When applied to tight gas formations in the Sultanate of Oman, the hybrid fracturing evolves from conventional designs for the purpose of successful fracture initiation, while still placing a successful job.

Download Full-text

Fracture Initiation Mechanisms of Multibranched Radial-Drilling Fracturing

Lithosphere ◽

10.2113/2021/3316083 ◽

2021 ◽

Vol 2021 (Special 1) ◽

Author(s):

Yu Bai ◽

Shangqi Liu ◽

Zhaohui Xia ◽

Yuxin Chen ◽

Guangyue Liang ◽

...

Keyword(s):

Stress Distribution ◽

Phase Angle ◽

Fracture Initiation ◽

Maximum Tensile Stress ◽

Tensile Failure ◽

Stress Profile ◽

Depth Difference ◽

Initiation Pressure ◽

Dip Angle ◽

Radial Drilling

Abstract Compared with conventional hydraulic fracturing, radial-drilling fracturing presents remarkable advantages and can effectively develop low-permeability reservoirs. The radial borehole can reduce formation fracture pressure and guide the fracture initiation and propagation. Due to the large radial borehole azimuth or the strong anisotropy of the reservoir, the single radial borehole may not efficiently guide the fracture propagation. The researchers proposed multibranched radial-drilling fracturing. However, the research on fracture initiation of multibranched radial-drilling fracturing is inadequate. Radial boreholes usually need certain dip angles to avoid penetrating the interlayer, but the effect of dip angle on the stress field has never been considered before. In this paper, an analytical model for predicting stress distribution around the main wellbore with multiradial boreholes of arbitrary dip angle, azimuth angle, and phase angle is established for the first time, taking full account of the influences of in situ stress, internal pressure, and fracture fluid infiltration on the stress field. The model is utilized to calculate the fracture initiation pressure (FIP) and point out the specific fracture initiation location (FIL). The influences of azimuth angle, dip angle, phase angle, depth difference, and the stress profile radius on fracture initiation pressure, fracture initiation location, and maximum tensile stress distribution are investigated, and a series of sensitivity analyses are carried out. The results show that the areas between the radial boreholes and closer to the walls of radial boreholes are more prone to tensile failure, which provides a theoretical basis for radial boreholes guiding fracture initiation. The reduction of phase angle and depth difference enhances the interference between radial wells, which is conductive to the formation of hydraulic fracture networks between them. As the dip angle increases, the stress becomes increasingly concentrated, and the preferential rock tensile failure becomes increasingly easy. The farther the stress profile is from the main wellbore axis, the smaller it will be influenced by the main wellbore. When the distance exceeds 2R, the maximum tensile stress distribution on the profile remains constant. The research enriches the fracture initiation mechanism of multibranched radial-drilling fracturing and provides guidance for optimizing radial borehole layout parameters of hydraulic fracturing directed by multiradial boreholes.

Download Full-text