Vertical Fracture Monitoring by Multi-Rate Through-Barrier Diagnostics

2021 ◽  
Author(s):  
Doszhan Yeleussinov ◽  
Arman Assangaliyev ◽  
Assel Ospanova ◽  
Vener Nagimov ◽  
Elena Kirpichikova ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Complex Geometry ◽  
Operating Conditions ◽  
Low Permeability ◽  
Injection Wells ◽  
Overlying Water ◽  
Fluid Movement ◽  
Vertical Fracture ◽  
Fracture Height

Abstract Hydraulic fracturing has been demonstrated to be a cost-effective method of developing low-permeability heterogeneous clastic reservoirs with vertical wells. In the presence of a thin shale layer as a seal, monitoring effective fracture height becomes extremely important. The conventional approach of a single-regime production logging may be ineffective due to the complex geometry of fluid flow in the near-wellbore zone around the well. The paper describes the experience of the multi-rate through barrier diagnostics as a method of improving hydraulic fracturing evaluation. The standard way to diagnose the effectiveness of hydraulic fracturing is to log a survey under current operating conditions. In general, temperature and passive spectral acoustic measurements provide useful information on identifying the boundaries of fluid movement behind production casing; however, it is difficult to determine if flow occurs in the vertical hydraulic fracture or channeling through damaged cement in a single-regime survey. The multi-rate through-barrier diagnostics allow analyzing the flow dynamics of the wellbore-fracture-formation system under different flowing regimes, enabling a more accurate assessment of fluid movement in the near-wellbore environment within several meters. The paper includes the results of the multi-rate logging survey campaign in vertical water injection wells drilled in a low-permeability clastic reservoir. A proppant-based hydraulic fracturing of the target formation was carried out in the wells. The geological structure of the developed reservoir includes a thin shale layer (break) that separates the target oil-saturated interval from the overlying water bearing reservoir. In order for the operator to optimize future stimulation programs identification of effective hydraulic fracture height in reservoir regions with different shale thicknesses is crucial. The upper boundaries of the injected fluid movement behind the casing were determined based on the survey results. Analysis of the acoustic and temperature field dynamics helped more reliably evaluate the nature of the fluid movement behind the casing, whether flow happens in vertical fracture or cement channeling. This results in a more precise quantitative assessment of the injection profile in the targeted and untargeted reservoir units.

scholarly journals An Investigation into the Effects of Weak Interfaces on Fracture Height Containment in Hydraulic Fracturing

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3245 ◽  
Author(s):  
Zheng ◽  
Liu ◽  
Zhang
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Control Method ◽  
Fracture Propagation ◽  
Rock Properties ◽  
Interface Fracture ◽  
Weak Interface ◽  
Height Control ◽  
Fracture Height ◽  
Fracture Height Containment

Hydraulic fracturing is an effective method for developing unconventional reservoirs. The fracture height is a critical geometric parameter for fracturing design but will be limited by a weak interface. Fracture containment occurs when fracture propagation terminates at layer interfaces that are weaker than the surrounding rock. It always occurs in multilayer formation. Therefore, the mechanism of fracture height containment guides fracture height control in hydraulic fracturing. In order to study the fracture containment mechanism, this paper first calculates the propagation behaviour of the fracture in 3D under the influence of a weak interface through a block discrete element method and analyzes the geometric characteristics of the fracture after it meets the weak interface. Then, the induced stress of the hydraulic fracture on the weak interface is calculated by fracture mechanics theory, and the mechanism of blunting at the fracture tip is explained. Then, two kinds of interface slippage that can lead to blunting of the fracture tip are discussed. Based on the behavior of shear slippage at the interface, a control method for multilayer fracturing in thin sand-mud interbed and pay zone fracturing in shale is proposed. The results show that the fracture height is still limited by the weak interface in the formation without the difference of in-situ stress and rock properties. Interface slippage is the main factor impeding fracture propagation. Fracture height containment can be adjusted and controlled by changing the angle between the hydraulic fracture, the interface, and the stress state to strengthen and stiffen the interface. This study has a certain guiding significance for fracture height control in the design of hydraulic fracturing of shale or thin sand-mud interbed reservoirs.

scholarly journals Hydraulic Fracture Propagation in Layered Rock: Experimental Studies of Fracture Containment

1984 ◽  
Vol 24 (01) ◽  
pp. 19-32 ◽  
Author(s):  
Lawrence W. Teufel ◽  
James A. Clark
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Horizontal Stress ◽  
Hydraulic Fractures ◽  
Low Permeability ◽  
Fracture Treatment ◽  
Gas Recovery ◽  
Layered Rock ◽  
Fracture Fluid ◽  
Minimum Horizontal Stress

Abstract Fracture geometry is an important concern in the design of a massive hydraulic fracture for improved natural gas recovery from low-permeability reservoirs. Determination of the extent of vertical fracture growth and containment in layered rock, a priori, requires an improved understanding of the parameters that may control fracture growth across layer interfaces. We have conducted laboratory hydraulic fracture experiments and elastic finite element studies that show that at least two distinct geologic conditions can inhibit or contain the vertical growth of hydraulic fractures in layered rock:a weak interfacial shear strength of the layers andan increase in the minimum horizontal compressive stress in the bounding layers. The second condition is more important and more likely to occur at depth. Differences in elastic properties within a layered rock mass may be important-not as a containment barrier perse, but in the manner in which variations in elastic properties affect the vertical distribution of the minimum horizontal stress magnitude. These results suggest that improved fracture treatment designs and an assessment of the potential success of stimulations in low-permeability reservoirs can be made by determining the in-situ stress st ate in the producing interval and bounding formations before stimulation. If the bounding formations have a higher minimum horizontal stress, then one can optimize the fracture treatment and maximize the ratio of productive formation fracture area to volume of fluid pumped by limiting bottomhole pressures to that of the bounding formation. Introduction In 1949, Clark introduced the concept of hydraulic fracturing to the petroleum industry. Since then, hydraulic fracture treatment to enhance oil and gas recovery in tight reservoir rocks has become standard practice. More recently, as a result of an increased need for better recovery techniques, massive hydraulic fracturing (MHF) has been used in low-permeability, gas-bearing sandstones in the Rock Mountain region and in Devonian shales of the Appalachian region, where it is uneconomical to retrieve gas in the conventional manner. Massive hydraulic fractures are designed to extend as much as 1000 m (3,281 ft) radially from the wellbore and generally require up to 1000 m3 (6,293 bbl) of fracture fluid. MHF has been developed by trial and error, and the results are uncertain in many situations. Some of these large-scale stimulation efforts have been successful, but others have been extremely disappointing failures. The reasons for these failures are not clear, but it seems likely that improved understanding of the fundamental mechanisms of hydraulic fracturing should suggest ways of improving the efficiency and reliability of the MHF stimulation technique or at least indicate where this technique can be applied successfully. Among the many technological problems encountered in MHF, one of the most important questions that must be answered properly to design a hydraulic fracture treatment for optimal gas recovery concerns the shape and overall geometry of the fracture. The question of fracture height and whether the hydraulic fracture will propagate into formations lying above and below the producing zone. When a fracture treatment is designed, the height of the fracture is the parameter about which the least is known, yet this influences all aspects of the design. A hydraulic fracture usually grows outward in a vertical plane and propagates above and below the packers as well as laterally away from the wellbore. Vertical propagation is undesirable whenever the fracturing is to be contained within a single stratigraphic interval. If the hydraulic fracture is not contained within the producing formation and propagates in both the vertical and lateral directions (an elliptical fracture), failure of the treatment can occur because the fracture fails to contact a sufficiently large area of the reservoir. Moreover, there is an effective loss of the expensive fracture fluid and proppant used to fracture the unproductive formations. An extreme example where the containment of a hydraulic fracture is essential is the case of developing a fracture in a gas-producing sandstone without fracturing through the underlying shale into another sandstone that is water-bearing. Therefore, it is of great economic importance to the gas industry to understand the parameters that can restrict the vertical propagation of massive hydraulic fractures. There are several parameters that are considered to have some effect on the vertical growth and possible containment of hydraulic fractures. SPEJ P. 19^

scholarly journals Experimental Investigation of Fracture Propagation Behavior Induced by Hydraulic Fracturing in Anisotropic Shale Cores

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 976 ◽  
Author(s):  
Zhaohui Chong ◽  
Qiangling Yao ◽  
Xuehua Li
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Bedding Plane ◽  
Operating Conditions ◽  
Breakdown Pressure ◽  
Bedding Planes ◽  
Propagation Pattern ◽  
Circumferential Displacement ◽  
Shale Reservoirs ◽  
Plane Mode

Hydraulic fracturing is a key technology for the development of unconventional resources such as shale gas. Due to the existence of numerous bedding planes, shale reservoirs can be considered typical anisotropic materials. In anisotropic shale reservoirs, the complex hydraulic fracture network (HFN) formed by the interaction of hydraulic fracture (HF) and bedding plane (BP) is the key to fracturing treatment. In this paper, considering the anisotropic angle, stress state and injection rate, a series of hydraulic fracturing experiments were conducted to investigate the effect of anisotropic characteristics of shale reservoirs on HFN formation. The results showed that the breakdown pressure increased first and then decreased when the anisotropic angle changed at 0°–90°, while the circumferential displacement had the opposite trend with a small difference. When θ = 0°, fracturing efficiency of shale specimens was much higher than that under other operating conditions. When θ ≤ 15°, the bedding-plane mode is ubiquitous in all shale reservoirs. While θ ranged from 30°–45°, a comprehensive propagation pattern of bedding-plane and crossing is presented. When θ ≥ 60°, the HFN pattern changes from comprehensive mode to crossing mode. The propagation pattern obtained from physical experiments were verified by theoretical analysis. The closure proportion of the circumferential displacement was the highest when the propagation pattern was the bedding-plane mode (θ ≤ 15°), following by crossing. The closure proportion was minimum only when the bedding-plane and crossing mode were simultaneously presented in the HFN. The results can provide some basic data for the design in hydraulic fracturing of tight oil/gas reservoirs.

Three-Dimensional Hydraulic Fracture Propagation in the Presence of Stress Variations

1983 ◽  
Vol 23 (06) ◽  
pp. 870-878 ◽  
Author(s):  
Ian D. Palmer ◽  
H.B. Carroll
Keyword(s):  
Boundary Condition ◽  
Hydraulic Fracture ◽  
Three Dimensional ◽  
Fracture Propagation ◽  
Rock Properties ◽  
Vertical Fracture ◽  
Hydraulic Fracture Propagation ◽  
Net Pressure ◽  
Fracture Height ◽  
Stress Contrast

Abstract Models of three-dimensional (3D) fracture propagation are being developed to study the effect of variations of stress and rock properties on fracture height and bottomhole pressure (BHP). Initially a blanket sand bounded by zones of higher minimum in-situ stress is considered, with stresses symmetrical about both the pay-zone axis and the wellbore. An elliptical fracture perimeter is assumed. Fluid flows are one-dimensional (1D) Newtonian in the direction of the pay zone. Two models, FL1 and FL2, are developed. In FL1, a discontinuous stress variation is approximated by a y2 variation in the vertical coordinate, and the fracture criterion, Ki = Kc, is satisfied at both major and minor axes. The net pressure at the tip, Lf, of the long axis required by the boundary condition Ki = Kc does not seem crucial in determining fracture height or BHP (compare with one group of published models that assumes p = 0 at Lf). Model FL2 properly represents the discontinuous stresses, and satisfies Ki = Kc at the wellbore but not at the tip of the long axis. A parametric study is made, with both models, of the comparative effects of stress contrast, Kc, pay-zone height, h, and Young's modulus, E, on fracture height and BHP. Results indicate that Kc does not have as much effect as either E or, at least for large stress contrasts. Model FL2 suggests the possibility of a rapid growth in fracture height as is reduced. Such modeling may be able to give an upper or "safe" limit on the pumping parameters ( and ) to ensure good containment. When the stress contrast is high, 700 psi [4826 kPa], an analytic derivation of BHP appears to be a good approximation for the parameters we use, if everywhere the fracture height is assumed equal to the pay zone height. Although leakoff is neglected here, subsequent modeling results show that, for leak off coefficients 0.001 ft- min [3.9 × 10 -5 m.s ], the results herein are a good approximation to the case when leak off is included. Introduction In their essence, models of hydraulic fracture propagation involve elasticity theory and fluid mechanics. The first is concerned with the fracture opening or width, w(p), as a function of net pressure on the fracture faces, while the second is concerned with the pressure drop, p(w), caused by the flow of viscous fluids in the fracture. Simultaneous solution of these equations includes a boundary condition that often takes the form Ki = Kc, where Ki is the stress-intensity factor at a point on the fracture tip, and Kc is the fracture toughness. The final solution is very complex in 3D, when a vertical fracture can expand vertically as well as horizontally along the pay zone. Thus, the first solutions were essentially two-dimensional (2D), and they assumed that the fracture height, hf, was fixed at the pay zone height, h. The 2D solutions were clustered in two groups as summarized by Nordgren, Perkins, and Geertsma and Haafkens. The first grouping, based on a model by Christianovich and Zheltov, assumed that the sides of an elongated, vertical fracture were parallel (i.e., free slippage between the pay and bounding zones, or no vertical stiffness). Other papers in this grouping included Geertsma and de Klerk, Daneshy and Settari. SPEJ P. 870^

scholarly journals WATERFLOOD-INDUCED FRACTURE ON THE INJECTION WELLS IN LOW-PERMEABILITY RESERVOIR OF ACHIMOV SEQUENCE

2018 ◽  
pp. 39-43
Author(s):  
A. V. Klimov-Kayanidi ◽  
R. T. Alimkhanov ◽  
E. S. Agureeva ◽  
R. M. Sabitov
Keyword(s):  
Hydraulic Fracturing ◽  
Low Permeability ◽  
Reservoir Pressure ◽  
Reservoir Properties ◽  
Injection Wells ◽  
Field Development ◽  
Low Permeability Reservoir ◽  
Fracture Formation ◽  
Maintenance Systems

Achimov sequence is characterized by high heterogeneity and low reservoir properties, that makes it impossible economically profitable field development without hydraulic fracturing and usage reservoir pressure maintenance systems. The research aims to develop recommendations for regulating the operations of injection wells, in conditions of waterflood-induced fracture formation. The recommendations can be used to further regulate the waterflooding system for the conditions of Achimov sequence.

Challenges in modelling of hydraulic fracturing in low-permeability coal seams with complex cleat networks and stress regimes

2019 ◽  
Vol 59 (1) ◽  
pp. 166
Author(s):  
Mohammad Ali Aghighi ◽  
Raymond Johnson Jr. ◽  
Chris Leonardi
Keyword(s):  
Numerical Methods ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fractured Reservoirs ◽  
Computational Cost ◽  
Naturally Fractured Reservoirs ◽  
Natural Fracture ◽  
Low Permeability ◽  
Natural Fractures ◽  
Fracture Development

Improved hydraulic fracturing models can better inform operational decisions regarding production from low-permeability coals and ultimately convert currently classified contingent resources to reserves. Improving current modelling approaches requires identification and investigation of the challenges involved in modelling hydraulic fracture stimulation in complex eastern Australian cases where permeability systems and stress regimes can vary significantly. This study investigated differences among existing and emerging advanced hydraulic fracture models and codes including numerical methods used to model fluid and rock behaviours during treatments; the ability to contextualise structure, behaviour and interaction of natural fractures with the propagating hydraulic fracture (e.g. cleat or natural fracture fabric, discrete fracture networks and pressure-dependent leak-off); and their capabilities in handling simultaneously growing or complex fracture development. One finding is that the new generation of models or codes that fully or partially use particle-based numerical methods are more capable in handling complexities associated with hydraulic stimulation of naturally fractured reservoirs. However, the computational cost and time for these models may cause concerns, particularly when modelling large reservoirs and treatments. Based on these limitations, many of the advanced, industry preferred, commercial hydraulic fracture simulators still choose to incorporate limited complexities with regard to natural fractures or represent them mathematically or implicitly. This investigation also indicates that most emerging models provide better representation of natural fractures, visualisation and integration into workflows for completion or stimulation design.

Integrated Hydraulic Fracture Geometry Evaluation Based on Pre-Cambrian Tight Silicylate Reservoir in South Oman Salt Basin

2022 ◽  
Author(s):  
Dmitrii Smirnov ◽  
Omar AL Isaee ◽  
Alexey Moiseenkov ◽  
Abdullah Al Hadhrami ◽  
Hilal Shabibi ◽  
...  
Keyword(s):  
Best Practices ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Hydraulic Fractures ◽  
Bond Quality ◽  
Fracture Geometry ◽  
Acoustic Anisotropy ◽  
Sonic Log ◽  
Before And After ◽  
Fracture Height

Abstract Pre-Cambrian South Oman tight silicilyte reservoirs are very challenging for the development due to poor permeability less than 0.1 mD and laminated texture. Successful hydraulic fracturing is a key for the long commercial production. One of the main parameter for frac planning and optimization is fracture geometry. The objective of this study was summarizing results comparison from different logging methods and recommended best practices for logging program targeting fracture geometry evaluation. The novel method in the region for hydraulic fracture height and orientation evaluation is cross-dipole cased hole acoustic logging. The method allows to evaluate fracture geometry based on the acoustic anisotropy changes after frac operations in the near wellbore area. The memory sonic log combined with the Gyro was acquired before and after frac operations in the cased hole. The acoustic data was compared with Spectral Noise log, Chemical and Radioactive tracers, Production Logging and pre-frac model. Extensive logging program allow to complete integrated evaluation, define methods limitations and advantages, summarize best practices and optimum logging program for the future wells. The challenges in combining memory cross-dipole sonic log and gyro in cased hole were effectively resolved. The acoustic anisotropy analysis successfully confirms stresses and predominant hydraulic fractures orientation. Fracture height was confirmed based on results from different logging methods. Tracers are well known method for the fracture height evaluation after hydraulic frac operations. The Spectral Noise log is perfect tool to evaluate hydraulically active fracture height in the near wellbore area. The combination of cased hole acoustic and noise logging methods is a powerful complex for hydraulic fracture geometry evaluation. The main limitations and challenges for sonic log are cement bond quality and hole conditions after frac operations. Noise log has limited depth of investigation. However, in combination with production and temperature logging provides reliable fit for purpose capabilities. The abilities of sonic anisotropy analysis for fracture height and hydraulic fracture orientation were confirmed. The optimum logging program for fracture geometry evaluation was defined and recommended for replication in projects were fracture geometry evaluation is required for hydraulic fracturing optimization.

Laboratory demonstration of hydraulic fracture height growth across weak discontinuities

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. MR93-MR105 ◽  
Author(s):  
Pengju Xing ◽  
Keita Yoshioka ◽  
Jose Adachi ◽  
Amr El-Fayoumi ◽  
Andrew P. Bunger
Keyword(s):  
Fracture Toughness ◽  
Hydraulic Fracture ◽  
Fluid Pressure ◽  
Height Growth ◽  
Rock Properties ◽  
Vertical Fracture ◽  
Parametric Space ◽  
Fracture Height ◽  
Stress Contrast ◽  
The Impact

Decades of research have led to numerous insights in modeling the impact of stresses and rock properties on hydraulic fracture height growth. However, the conditions under which weak horizontal interfaces are expected to impede height growth remain for the most part unknown. We have developed an experimental study of the impact of weak horizontal discontinuities on hydraulic fracture height growth, including the influences of (1) abrupt stress contrasts between layers, (2) material fracture toughness, and (3) contrasts of stiffness between the reservoir and bounding layers. The experiments are carried out with an analog three-layered medium constructed from transparent polyurethane, considering toughnesses resisting vertical fracture growth. There are four observed geometries: containment, height growth, T-shape growth, and the combination of height growth and T-shape. Results are developed in a parametric space embodying the influence of the horizontal stress contrast, vertical stress, and horizontal barrier stress contrast, as well as the fluid pressure. The results indicate that these cases fall within distinct regions when plotted in the parametric space. The locations in the parametric space of these regions are strongly impacted by the vertical fracture toughness: Increasing the value of the vertical interface fracture toughness leads to a suppression of height growth in favor of containment and T-shaped growth. Besides providing detailed experimental data for benchmarking 3D hydraulic fracture simulators, these experiments show that the fracture height is substantially less than would be predicted in the absence of the weak horizontal discontinuities.

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