scholarly journals Influence of Volume Fracturing on Casing Stress in Horizontal Wells

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2057
Author(s):  
Jingpeng Wang ◽  
Youming Xiong ◽  
Zongyu Lu ◽  
Jiangang Shi ◽  
Jiwei Wu
Keyword(s):  
Temperature Effect ◽  
Temperature Change ◽  
Temperature Stress ◽  
Horizontal Wells ◽  
Wellhead Pressure ◽  
Collapse Strength ◽  
Fracturing Process ◽  
Casing Strength ◽  
Volume Fracturing ◽  
Casing Collapse

In horizontal wells, the casing string is affected by the gravity effect, temperature effect, swelling effect, bending effect, friction effect and other mechanical effects. In view of this situation, the mathematical models of casing swelling effect and temperature effect caused by volume fracturing are established. The case analysis shows that the length of the unsealed section in the vertical section has a great influence on the axial shortening of the casing during fracturing. With the increase of the unsealed section length, the axial shortening of the casing increases gradually under the same wellhead pressure. In the process of fracturing, repeated squeezing and pressurization lead to periodic changes of the wellhead pressure, casing deformation and load, which leads to fatigue damage and even fracture of casing. At the same time, a large amount of fracturing fluid is continuously injected through the casing during the fracturing process, which makes the wellbore temperature change greatly. The additional stress caused by the temperature change reduces the casing strength, which has an important impact on the wellbore integrity. The mathematical model of temperature stress and its effect on the casing strength during volume fracturing is established. With the increase of the temperature stress acting on the casing, the casing collapse strength decreases gradually. When the temperature stress reaches 200 MPa, the casing collapse strength decreases to 84% of the original. The research results can provide a reference for the casing integrity design and control in the horizontal well fracturing process.

scholarly journals Volume fracturing of deep shale gas horizontal wells

2017 ◽  
Vol 4 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Tingxue Jiang ◽  
Xiaobing Bian ◽  
Haitao Wang ◽  
Shuangming Li ◽  
Changgui Jia ◽  
...  
Keyword(s):  
Shale Gas ◽  
Horizontal Wells ◽  
Volume Fracturing

Mechanical Mechanism Analysis of Longitudinal Cracks Appeared in a Large Cable-Stayed Bridge Cable Tower

2012 ◽  
Vol 226-228 ◽  
pp. 1626-1629
Author(s):  
Liang Liang Yang ◽  
Jun Dong ◽  
Jie He ◽  
Tian Liang
Keyword(s):  
Numerical Simulation ◽  
Temperature Effect ◽  
Temperature Stress ◽  
Design Process ◽  
Mechanism Analysis ◽  
Original Design ◽  
Bridge Inspection ◽  
Cable Stayed Bridge ◽  
Bridge Cable ◽  
Longitudinal Cracks

The cable-stayed bridge which has been found longitudinal cracks in tower is taken as the background, combining with the original design information and the results of bridge inspection. The numerical simulation on temperature effect of cable tower has been done with MIDAS/Civil, and the results have the same trend with observed in bridge inspection, indicating that the cracks in tower probably are caused by temperature effect. Then, some suggestions are raised in the end of this paper about how to deal with these cracks. This work could be a valuable reference for similar large cable-stayed bridge. And the temperature stress should be paid more attention in design process to avoid appearance of temperature cracks which affect beauty and durability of structure.

Examination of Commercial Casing Collapse Strength Under Axial Loading

1982 ◽  
Vol 104 (4) ◽  
pp. 343-348 ◽  
Author(s):  
T. Tamano ◽  
Y. Inoue ◽  
H. Mimura ◽  
S. Yanagimoto
Keyword(s):  
Axial Load ◽  
Axial Stress ◽  
Axial Loading ◽  
External Pressure ◽  
Plastic Collapse ◽  
Slight Effect ◽  
Collapse Pressure ◽  
Minimum Value ◽  
Collapse Strength ◽  
Casing Collapse

Collapse testing of commercial API grade 7-in. casing was conducted under combined external pressure and axial load. The measured collapse pressure was considerably higher than the API minimum value, especially for the large D/t ratio, as expected. For the casings of large D/t ratio, the measured collapse pressure was a little smaller than the theoretical value for ideal pipe and the axial stress had a slight effect on the collapse pressure. In the range of plastic collapse, the measured collapse pressure was not less than the yield pressure for ideal pipe except near the boundary of the elastic and plastic collapse ranges.

scholarly journals Theoretical and Simulation Study on the Collapse Strength of a Curved Casing in Horizontal Wells

2019 ◽  
Vol 22 ◽  
pp. 84-92
Author(s):  
Yinping Cao ◽  
YiHua Dou ◽  
MingFei Li ◽  
HongJuan Suo
Keyword(s):  
Simulation Study ◽  
Horizontal Wells ◽  
Collapse Strength

Impediments to Refracturing Success in Shale Reservoirs

2021 ◽  
Author(s):  
Clay Kurison
Keyword(s):  
Hyperbolic Equation ◽  
Reservoir Simulation ◽  
Analytical Techniques ◽  
Horizontal Wells ◽  
B Value ◽  
Hydraulic Fractures ◽  
Fracturing Fluid ◽  
Minimal Impact ◽  
Wellhead Pressure ◽  
The Matrix

Abstract Stimulations in early horizontal wells in most shale plays are characterized by few and widely spaced perforation clusters, and low amounts of injected fracturing fluid and proppant. Low recovery from these wells has motivated refracturing although outcomes have been interpreted to range from successful to minimal impact based on operator specific evaluations. To tailor available technologies and improve quantification of upsides, there is need for mapping the spatial distribution of remaining resources and developing simpler but reliable analytical techniques. In this study, hydraulic fractures were assumed to be planar in a matrix with low porosity and ultra-low permeability. Consideration of natural fractures and their interaction with stimulation fluids led to addition of distributed fracture networks adjacent to the planar hydraulic fractures to define the composite fracture corridors. A sector model with the aforementioned architecture was used in reservoir simulation to investigate induced temporal and spatial drainage. These findings were used to explain the efficacy of widely used refracturing techniques and how post-refracturing reservoir response can be analyzed. Results from reservoir simulation showed remaining reserves were in the matrix between earlier placed hydraulic fractures aligned along initial perforation clusters, and beyond tips of hydraulic fractures. Upside from refracs could come from creation of new fractures in the matrix between earlier placed fractures and extension of tips of early fractures into virgin matrix. Assessment of these scenarios found the former to be optimal although depletion and existing perforations would limit the stimulation efficiency of new perforations. The second scenario would require large volumes of fracturing fluid to re-initiate fracture propagation. Yet this could trigger interference with offsets or affect drilling and stimulation of planned wells in adjacent acreage. For treatment efficiency, re-casing horizontal wells with competent liners and use of coiled tubing with straddle packers appears a better solution for bypassing old perforations. For the near wellbore and far field, re-stimulating new perforations at low injection rates could allow extension of fractures in virgin matrix surrounded by depleted strata. Real-time surveillance would be essential for mapping flow paths of refracturing fluid. For assessment of refracturing, actual and simulated flow exhibited persistent linear flow (PLF) that could be matched by Arps hyperbolic equation with a b value of 2. Incorporation of a novel fracture geometry factor (FGF) yielded an Arps-based equation that was tested on North American shale refracturing cases that often use post-treatment peak rate and wellhead pressure as measures of success. This study identified factors hindering the success of refracturing and proposed a modified Arps hyperbolic equation to analyze refracturing production data.

Utilization of Hydraulic Completion Units in the Delaware Basin

2021 ◽  
Author(s):  
J. H. Frantz ◽  
M. L. Tourigny ◽  
J. M. Griffith
Keyword(s):  
Paradigm Shift ◽  
Horizontal Wells ◽  
Wellhead Pressure ◽  
Delaware Basin ◽  
Coiled Tubing ◽  
Operational Time ◽  
Shift Change

Abstract In conjunction with the industry and basin-wide paradigm shift to drilling and completing extended laterals, Matador Resources Company (the operator) made significant plans in 2018 that would focus activity toward wells with laterals greater than one-mile. One operational hurdle to overcome in this shift change was the effective execution of removing frac plugs and sand at increased depths during a post-stimulation frac plug millout. Utilization of coiled-tubing units (CTUs) had been proven to be a successful millout method in one-mile laterals, but not without risk. Rig-assisted snubbing units coupled with workover rigs (WORs) provided for less risk with higher pulling strength capabilities and the ability to rotate tubing, but would often require operational time of up to twice that of typical coiled-tubing unit millouts. The stand-alone, rigless Hydraulic Completion Unit (HCU) was ultimately tested as a solution and proved to alleviate risks in extended lateral millouts while providing operational time and cost comparable to coiled-tubing units. The operator has since performed post-stimulation frac plug millouts on ~45 horizontal wells in the Delaware Basin using HCUs. The majority of these wells carried lateral lengths of over 1.5 miles. Results and benefits observed by the operator include but are not limited to the list below: 1.) Ability to safely and consistently reach total depth (TD) on extended laterals through increased snubbing/pickup force and the HCU's pipe rotating ability 2.) Ability to pump at higher circulation rates in high-pressured wells (>3,500 psi wellhead pressure) to assist in effective wellbore cleaning 3.) Smaller footprint which allows for the utilization of two units simultaneously on multi-well pads 4.) Time and cost comparable to a standard coiled-tubing millout, particularly on multi-well pads.

Solving Measures and Application of Super-Long Structure under Temperature Problem

2014 ◽  
Vol 915-916 ◽  
pp. 1054-1057
Author(s):  
Yong Sheng Wang ◽  
Li Hua Wu ◽  
Zong Hai Xie
Keyword(s):  
Temperature Effect ◽  
Temperature Stress ◽  
Concrete Structure ◽  
Engineering Application ◽  
Shrinkage Stress ◽  
Expansion Joint ◽  
Design Basis ◽  
Temperature Problem ◽  
Environment Temperature ◽  
Structure Plane

Due to the long structure plane size of the super-long concrete structure ,considering the effect of environment temperature on the structure in design. the expansion joint is arranged to solve the problem of temperature stress and shrinkage stress in the past.This paper discusses several new solutions on the temperature problems of super-long structure,and the unbonded prestressed technology in the engineering application of super-long structure under temperature effect to solve problems to do the analysis,provides the design basis for engineering designers to consider the temperature effect.

A New OCTG Strength Equation for Collapse Under External Load Only

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Yong-Xing Sun ◽  
Yuan-Hua Lin ◽  
Zhong-Sheng Wang ◽  
Tai-He Shi ◽  
Hong-Bin Liu ◽  
...  
Keyword(s):  
External Load ◽  
Work Group ◽  
Safety Margin ◽  
Predictive Values ◽  
Collapse Strength ◽  
Study Results ◽  
Collapse Model ◽  
Casing Strength ◽  
New Equation ◽  
Experimental Comparisons

The influence of manufacturing technology and imperfections on casing collapse strength is not considered in API bulletin 5C3. In the meantime, the current casing true collapse strength cannot be predicted accurately by API bulletin 5C3. For these cases, the joint API/ISO work group ISOTC67 SC5 WG2b has proposed the current API bulletin 5C3 and presented a new collapse strength model with manufacturing imperfections, such as ovality, eccentricity, residual stress, etc., which improves the casing strength calculation accuracy and benefits much more for casing strength design rather than just using API bulletin 5C3. The study on the new ISO collapse model has found that it cannot be used to predict the collapse strength of all pipe sizes, and the current study results are greatly different from actual conditions, which is not the last goal to propose API bulletin 5C3 for the joint API/ISO work group ISOTC67 SC5 WG2b. So, based on the new ISO collapse model, a new oil country tubular goods (OCGT) strength equation, “new equation” for predicting all OCTG sizes collapse strength under external load only has been presented in this paper. Numerical and experimental comparisons show that there is a safety margin appropriate to the desired target reliability level between the predictive values calculated by the new equation and test collapse data, and the new equation calculation accuracy is higher than that of API and ISO, which will make great improvements in the casing design of deep and superdeep wells on the basis of guaranteeing casing material safety.

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