Geomechanic models using finite element methods show how Cooper Basin structure and sand body geometry impacts stress variation and hydraulic fracturing results

2015 ◽  
Vol 55 (2) ◽  
pp. 439
Author(s):  
Nicole Ditty ◽  
Dennis Cooke
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Hydraulic Fracture ◽  
Local Stress ◽  
Three Dimensions ◽  
Stress Regime ◽  
Structural Position ◽  
The Impact ◽  
Cooper Basin ◽  
Hydraulic Fracture Stimulation

Unconventional reservoirs such as tight sands and shales require hydraulic fracture stimulation to improve productivity. The success of reservoir stimulation is controlled by the local stress field but decisions are often made knowing only the average stress field. This study uses geomechanical modelling to help explain lateral stress variability using structural geology, lithology contrast and boundary conditions. Changes in vertical and horizontal stresses are related to depth, lithology and structural position, yet these effects are not always accounted for. This is evident in the Cooper Basin, Australia, where, for example, unexpected changes in minifrac pressure are commonly observed in adjacent wells in a field. This study presents results from conceptual geomechanical models to help explain such variations in stress. Model scenarios are constructed using finite element package to investigate the impact of structural position, rock mechanical properties and stress regime on the patterns of horizontal and vertical stress magnitudes in a layered antiform sequence. Key findings suggest that: stress magnitude is affected by structural positioning; different patterns of stress exist across different lithologies; and, stress regime impacts on patterns of stress, especially in combination with curvature of structures. These challenge traditional methods of one-dimensional mechanical earth models and show that, rather than employing methods developed for simple layer-cake geology in extensional basins, geomechanical models should be constructed in two- or even three-dimensions. Results of this study highlight part of the solution to the unconventional resource potential of the Cooper Basin. Improved prediction of field-scale stress variations should enable further optimisation of hydraulic fracture stimulation treatments.

scholarly journals Three-dimensional approach to understanding the relationship between the Plio-Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina

2015 ◽  
Vol 7 (1) ◽  
pp. 459-494
Author(s):  
L. Giambiagi ◽  
S. Spagnotto ◽  
S. M. Moreiras ◽  
G. Gómez ◽  
E. Stahlschmidt ◽  
...  
Keyword(s):  
Stress Field ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Stress Regime ◽  
Basin Inversion ◽  
Structural Style ◽  
Tectonic Inversion ◽  
The Impact ◽  
The Relationship

Abstract. The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of rift basin inversion contemporaneous to the advance of the Andean thrust front, during the Plio-Quaternary. This basin is one of the most important sedimentary basins in a much larger Triassic NNW-trending depositional system along the southwestern margin of the Pangea supercontinent. The amount and structural style of inversion is provided in this paper by three-dimensional insights into the relationship between inversion of rift-related structures and spatial variations in late Cenozoic stress fields. The Plio-Quaternary stress field exhibits important N–S variations in the foreland area of the Southern Central Andes, between 33 and 34° S, with a southward gradually change from pure compression with σ1 and σ2 being horizontal, to a strike-slip type stress field with σ2 being vertical. We present a 3-D approach for studying the tectonic inversion of the sub-basin master fault associated with strike-slip/reverse to strike-slip faulting stress regimes. We suggest that the inversion of Triassic extensional structures, striking NNW to WNW, occurred during the Plio–Pleistocene in those areas with strike-slip/reverse to strike-slip faulting stress regime, while in the reverse faulting stress regime domain, they remain fossilized. Our example demonstrates the impact of the stress regime on the reactivation pattern along the faults.

Microseismicity-constrained discrete fracture network models for stimulated reservoir simulation

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. B37-B47 ◽  
Author(s):  
Sherilyn Williams-Stroud ◽  
Chet Ozgen ◽  
Randall L. Billingsley
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Network ◽  
Discrete Fracture Network ◽  
Three Dimensions ◽  
Fracture Flow ◽  
Signal To Noise ◽  
Discrete Fracture ◽  
Microseismic Events ◽  
The Impact ◽  
Dfn Model

The effectiveness of hydraulic fracture stimulation in low-permeability reservoirs was evaluated by mapping microseismic events related to rock fracturing. The geometry of stage by stage event point sets were used to infer fracture orientation, particularly in the case where events line up along an azimuth, or have a planar distribution in three dimensions. Locations of microseismic events may have a higher degree of uncertainty when there is a low signal-to-noise ratio (either due to low magnitude or to propagation effects). Low signal-to-noise events are not as accurately located in the reservoir, or may fall below the detectability limit, so that the extent of fracture stimulated reservoir may be underestimated. In the Bakken Formation of the Williston Basin, we combined geologic analysis with process-based and stochastic fracture modeling to build multiple possible discrete fracture network (DFN) model realizations. We then integrated the geologic model with production data and numerical simulation to evaluate the impact on estimated ultimate recovery (EUR). We tested assumptions used to create the DFN model to determine their impact on dynamic calibration of the simulation model, and their impact on predictions of EUR. Comparison of simulation results, using fracture flow properties generated from two different calibrated DFN scenarios, showed a 16% difference in amount of oil ultimately produced from the well. The amount of produced water was strongly impacted by the geometry of the DFN model. The character of the DFN significantly impacts the relative amounts of fluids produced. Monitoring water cut with production can validate the appropriate DFN scenario, and provide critical information for the optimal method for well production. The results indicated that simulation of enhanced permeability using induced microseismicity to constrain a fracture flow property model is an effective way to evaluate the performance of reservoirs stimulated by hydraulic fracture treatments.

Finite Element Simulation of Tensile Behaviors in the Elastic Region for PP/Nano-TiO2 Composites

2010 ◽  
Vol 150-151 ◽  
pp. 1819-1823
Author(s):  
Yu Jiao Wu ◽  
Ming Rui Gao ◽  
Yu Ling Chen ◽  
Juan Li ◽  
Shao Lin Ju
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Volume Fraction ◽  
Local Stress ◽  
Von Mises Stress ◽  
Analysis Model ◽  
Nano Tio2 ◽  
Two Phase ◽  
Element Analysis ◽  
Von Mises

Polypropylene(PP)/nano-TiO2 composites were prepared by the melt intercalation molding. Based on the assumption of continuum mechanics model for materials, a finite element analysis model for the composites was constructed using ANSYS 11.0 software. In the stage of deformation (pre-yield regime) the response mechanism of the stress and the strain for composites was investigated, and the von mises stress field of PP/nano-TiO2 composites has also been simulated. It was found that the simulation results are Consistent with the testing results at low volume strain level. The results simulated using the 2D model are accurate with the experimental results. If the volume fraction of particles is less, other particles have little influence on the local stress field of a certain particle, no obvious overlap or cross of the stress field could be found between two neighboring particles. While applying different loads, the stress jumps to maximum stress value in the interaction region of the two phase firstly, and then it occurs that the particles debond with the matrix.

Methodology for assessing original gas in place and estimated ultimate recovery from a tight marine formation using hydraulic fracture stimulation modelling

2017 ◽  
Vol 57 (1) ◽  
pp. 136 ◽  
Author(s):  
Matthew Goldman ◽  
Raymond L. Johnson
Keyword(s):  
United States ◽  
Hydraulic Fracture ◽  
The United States ◽  
Reservoir Rock ◽  
Gas Field ◽  
Stress Regime ◽  
Marcellus Formation ◽  
Half Length ◽  
Estimated Ultimate Recovery ◽  
Hydraulic Fracture Stimulation

Operators in Australia are currently exploring similar geological settings to the tight marine unconventional petroleum systems of the United States, in the hope of emulating the North American success. This study sets out the methodology and models required to undertake an analysis of a tight marine source and reservoir rock to estimate its production potential, with particular attention given to modelling the required hydraulic fracture stimulation. The project target formation is the tight marine Log Creek Formation, which forms the source rock to the overlying proved Gilmore Gas Field in the Adavale Basin in Central Queensland. The Marcellus Formation in the Appalachian Basin in the Northeastern United States is an assumed analogue to the Adavale Basin; data from the Marcellus Formation was used when unavailable for the Adavale Basin. Initially, formation evaluation was undertaken to determine key parameters such as total organic carbon (TOC), mineralogy and stress regime. Once the formation had been characterised, a fracture stimulation model was built to determine the hydraulic fracture stimulation treatment design, which optimised the lateral landing depth, hydraulic fracture spacing, conductivity and half‐length. In particular, it is important to determine the lateral landing depth and fracture half‐length with confidence, as they will define the stimulated reservoir volume (SRV), which sets the upper boundary on original gas in place (OGIP) and estimated ultimate recovery (EUR) of gas. OGIP was estimated using a probabilistic model incorporating an adjustment for absorbed gas volume. Finally, a reservoir simulation was undertaken using a single well composite multi‐fracture model to obtain EUR.

Piping Local Stresses for Solid Versus Hollow Attachments

2005 ◽  
Author(s):  
C. Basavaraju ◽  
R. C. Fox
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Cylindrical Shells ◽  
Local Stress ◽  
Support Design ◽  
Element Analysis ◽  
Stress Evaluation ◽  
Local Stresses ◽  
Asme Code ◽  
The Impact

The simple and most commonly used WRC-107 (Welding Research Bulletin #107) Bijlaard methodology for local stress evaluation addresses cylindrical shells and pipes with solid circular, rectangular, and square attachments only. Hollow circular, square, or rectangular tubular shaped attachments on cylindrical shells, though commonly used, are not addressed in WRC-107. ASME Code Case N-392 addresses hollow circular attachments on pipes but is known to be conservative. This paper studies commonly encountered sizes of hollow circular, hollow square, and hollow rectangular attachments of various wall thicknesses on piping utilizing rigorous finite element analysis (FEA) method to obtain the local stresses at the pipe/attachment interface due to mechanical loads. A total of fifty (50) finite element models were analyzed to study the most frequently used configurations. The impact of attachment wall thickness including solid attachment will be addressed. A comparison of finite element results with WRC-107 solid attachment results, when applicable, will be made. Recommendations and guidelines are provided based on the results of the FEA study. The objective is to reduce conservatism, and hence the associated cost in piping and pipe support design by optimizing the round attachment’s wall thickness.

Pre-Tensioning Fixture Development for Machining of Thin-Walled Components

2011 ◽  
Vol 314-316 ◽  
pp. 319-326
Author(s):  
Jia Yuan He ◽  
Yan Wang ◽  
Nabil Gindy
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Scientific Research ◽  
Optimal Performance ◽  
Machining Process ◽  
Fixture Design ◽  
Finite Element Analyses ◽  
Machining Forces ◽  
Thin Walled ◽  
The Impact

Pre-tensioning forces are, in essence, the application of selective clamping forces on components prior to machining to create a “stress field” envelope that aids the processes of components. Utilisation of pretension forces prior to process offers advantages of increasing component rigidity, thus reducing the deflection from process, and holding the components in a way to counteract the machining forces etc. However, the scientific research of pre-tensioning forces has not been extensively or comprehensively investigated. The aim of this paper is to investigate the impact of applying pre-tensioning forces on thin walled components, and more specifically, focuses on the development of appropriate fixtures to achieve optimal performance from pre-tensioning. Finite Element Analyses (FEA) were used intensively to analyse the impact of pre-tensioning forces on components during machining process considering machining deflections. After the FE models were validated from experiments, stiffness of components under the action of pre-tensioning forces can be predicted for the development of future fixture design

Using a 3D hydraulic fracture simulator to assess the impact of perforation design on high near-wellbore pressure loss in the Cooper Basin

2016 ◽  
Vol 56 (2) ◽  
pp. 569
Author(s):  
Nicholas Eades ◽  
Mohit Patter ◽  
Aldi Smokaj
Keyword(s):  
Hydraulic Fracture ◽  
Pressure Loss ◽  
Interval Length ◽  
Vertical Wells ◽  
Differential Stress ◽  
The Past ◽  
Industry Standard ◽  
Wellbore Pressure ◽  
The Impact ◽  
Cooper Basin

Fracture stimulation in the Cooper Basin has long been challenged by high near-wellbore pressure loss (NWBPL) present in hydraulic fracture treatments. Though many strategies have been applied to either mitigate or prevent this, the industry is still in need of a broadly applicable, economic and practical solution. An approach that has significant potential, and targets NWBPL from its foundation, is perforation design. Perforation design has been shown in the past to have a significant effect on the initiation of a fracture and the success of its continued propagation. A commercial 3D hydraulic fracture simulator has been applied to data from Cooper Basin wells. These vertical wells contain tight sand intervals and are characterised by high differential stress. A sensitivity analysis has been performed using industry-standard GOHFER software, focusing on parameters including perforation diameter, shot density, interval length, number of intervals, and shot spacing. Though many previous authors have suggested that perforation design has limited impact on pressure loss, the analysis performed in this study indicates that there are methods inherent in perforation design that can impact on high NWBPL. In particular, this study has noted a potential for many cost-saving strategies that could be applied to future completions. This is an innovative study that examines the underlying links between perforation design and the resulting near-wellbore pressure loss. It focuses on problematic areas of the Cooper Basin in the hope that by examining these links useful recommendations can be made to the industry.

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