HYDRAULIC FRACTURING EVALUATION UTILIZING SINGLE-WELL S-WAVE IMAGING: IMPROVED PROCESSING METHOD AND FIELD EXAMPLES

2020 ◽  
Author(s):  
Peng Liu ◽  
◽  
Hongliang Wu ◽  
Yusheng Li ◽  
Kewen Wang ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Processing Method ◽  
S Wave ◽  
Wave Imaging ◽  
Single Well

Single-well S-wave imaging using multicomponent dipole acoustic-log data

Geophysics ◽  
2009 ◽  
Vol 74 (6) ◽  
pp. WCA211-WCA223 ◽  
Author(s):  
Xiao-Ming Tang ◽  
Douglas J. Patterson
Keyword(s):  
Field Data ◽  
Wave Radiation ◽  
Dipole Source ◽  
Directional Sensitivity ◽  
S Wave ◽  
Fracture Characterization ◽  
Processing Application ◽  
S Waves ◽  
Wave Imaging ◽  
Single Well

Single-well S-wave imaging has several attractive features because of its directional sensitivity and usefulness for fracture characterization. To provide a method for single-well acoustic imaging, we analyzed the effects of wave radiation, reflection, and borehole acoustic response on S-wave reflection measurements from a multicomponent dipole acoustic tool. A study of S-wave radiation from a dipole source and the wave’s reflection from a formation boundary shows that the S-waves generated by a dipole source in a borehole have a wide radiation pattern that allows imaging of reflectors at various dip angles crossing the borehole. More importantly, the azimuthal variation of the S-waves, in connection with the multicomponent nature of a cross-dipole tool, can determine the strike of the reflector. We used our theoretical foundation for borehole S-wave imaging to formulate an inversion procedure for field data processing. Application to field data validates the theoretical results and demonstrates the advantages of S-wave imaging. Application to near-borehole fracture imaging clearly demonstrates S-wave azimuthal sensitivity to fracture orientation.

Simultaneous Hydraulic Fracturing Improves Completion Efficiency and Lowers Costs Per Foot

2021 ◽  
Author(s):  
David Russell ◽  
Price Stark ◽  
Sean Owens ◽  
Awais Navaiz ◽  
Russell Lockman
Keyword(s):  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Horizontal Wells ◽  
Asset Returns ◽  
Gas Production ◽  
Well Performance ◽  
Additional Time ◽  
Oil And Gas Production ◽  
Single Well ◽  
Lateral Length

Abstract Reducing well costs in unconventional development while maintaining or improving production continues to be important to the success of operators. Generally, the primary drivers for oil and gas production are treatment fluid volume, proppant mass, and the number of stages or intervals along the well. Increasing these variables typically results in increased costs, causing additional time and complexity to complete these larger designs. Simultaneously completing two wells using the same volumes, rates, and number of stages as for any previous single well, allows for more lateral length or volume completed per day. This paper presents the necessary developments and outcomes of a completion technique utilizing a single hydraulic fracturing spread to simultaneously stimulate two or more horizontal wells. The goal of this technique is to increase operational efficiency, lower completion cost, and reduce the time from permitting a well to production of that well—without negatively impacting the primary drivers of well performance. To date this technique has been successfully performed in both the Bakken and Permian basins in more than 200 wells, proving its success can translate to other unconventional fields and operations. Ultimately, over 200 wells were successfully completed simultaneously, resulting in a 45% increase in completion speed and significant decrease in completion costs, while still maintaining equivalent well performance. This type of simultaneous completion scenario continues to be implemented and improved upon to improve asset returns.

Elastic-wave evaluation of downhole hydraulic fracturing: Modeling and field applications

Geophysics ◽  
2018 ◽  
Vol 83 (1) ◽  
pp. D1-D8 ◽  
Author(s):  
Yuan-Da Su ◽  
Zhen Li ◽  
Song Xu ◽  
Chun-Xi Zhuang ◽  
Xiao-Ming Tang
Keyword(s):  
Wave Propagation ◽  
Hydraulic Fracturing ◽  
Elastic Wave ◽  
Fracture Network ◽  
Velocity Variation ◽  
Fracture Aperture ◽  
Filling Material ◽  
S Wave ◽  
Velocity Change ◽  
Main Fracture

We numerically simulate elastic-wave propagation along a fluid-filled borehole with a hydraulically fractured formation. The numerical model is based on the results of hydraulic fracturing on laboratory specimens. Two typical models are simulated: a main fracture crossing the borehole and a fracture network extending from the borehole. In addition, both models contain small, secondary fractures surrounding the borehole. Our result indicates that wave propagation in the main-fracture model is characterized by significant S-wave anisotropy for polarization along and normal to the fracture orientation, with the magnitude of anisotropy depending on the fracture aperture and filling material. In contrast, no significant anisotropy is observed for the fracture network model. In both models, wave propagation is significantly affected by small-fracture-induced near-borehole velocity variation. Our modeling results provide a theoretical foundation for evaluating hydraulic fracturing using the borehole acoustic logging. The hydraulic fracture-induced S-wave anisotropy can be evaluated with the cross-dipole S-wave logging, and the fracturing-induced velocity change can be detected by acoustic traveltime tomography. We used field data examples to demonstrate the effectiveness and practicality of using the borehole acoustic techniques for hydraulic fracturing evaluation.

Identification of Well Completion and Hydraulic Fracturing Performance Factors of Initial Development Wells within a Tight Oil Project in West China

2015 ◽  
Author(s):  
Jing Zhang ◽  
Xu Jiangwen ◽  
Hong Jiang ◽  
Tobias Judd ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Reservoir Characterization ◽  
Junggar Basin ◽  
Microseismic Monitoring ◽  
Western China ◽  
Rapid Decline ◽  
Initial Development ◽  
Chemical Tracers ◽  
Well Completion ◽  
Single Well

Abstract The early development of a systematic approach to well completion practices centralized around multistage hydraulic fracturing treatments is often the critical component to sustainable reservoir exploitation and development. Unfortunately, the exploitation of either exploratory or underdeveloped resources often has a number of issues that include the understanding of geological heterogeneity with different results observed within close proximity and the need to optimize completion techniques to offset the potential rapid decline in well productivity. For these cases, well completion and stimulation practices are of utmost importance with the optimization and evaluation of such designs to include and account for the integration of all reservoir and geomechanical parameters. Recent vertical well results from initial exploratory wells combined with single-well horizontal pilot wells has accelerated the development plans for the Jimusaer field located in the Junggar basin of western China. This field covers a surface area of 300,000 acres with the targeted reservoir being located between 2,300 to 4,255 m true vertical depth (TVD). The application of horizontal wells from multiwell pads with each well consisting of up to 23 hydraulic fracturing treatments was meant to exploit large volumes of hydrocarbon reserves that were previously thought unattainable. Operationally, the first four wells consisted of 62 hydraulic fracturing stages and were executed within a 28-day period. The project included the application of an integrated workflow including reservoir characterization along the length of the horizontal well lateral, deployment of novel multistage openhole completion techniques with dissolvable isolation technology, factory fracturing approach with all stages being monitored by microseismic monitoring, and application of chemical tracers on selected stages to identify zonal contribution during flowback and cleanup operations. This paper describes how the acquisition of crucial reservoir and fracturing data combined with operational performance can identify areas for improvement of future completions while strengthening existing ones.

Acoustic velocity and permeability of acidized and propped fractures in shale

Geophysics ◽  
2021 ◽  
pp. 1-55
Author(s):  
Jihui Ding ◽  
Anthony C. Clark ◽  
Tiziana Vanorio ◽  
Adam D. Jew ◽  
John R. Bargar
Keyword(s):  
Fluid Flow ◽  
Hydraulic Fracturing ◽  
Seismic Velocity ◽  
Rock Physics ◽  
Elastic Stiffness ◽  
Acoustic Velocity ◽  
S Wave ◽  
Fracture Permeability ◽  
Mechanical Fracture ◽  
Flow Pathways

From geochemical reactions to proppant emplacement, hydraulic fracturing induces various chemo-mechanical fracture alterations in shale reservoirs. Hydraulic fracturing through the injection of a vast amount and variety of fluids and proppants has substantial impacts on fluid flow and hydrocarbon production. There is a strong need to improve our understanding on how fracture alterations affect flow pathways within the stimulated rock volume and develop monitoring tools. We conducted time-lapse rock physics experiments on clay-rich (carbonate-poor) Marcellus shales to characterize the acoustic velocity and permeability responses to fracture acidizing and propping. Acoustic P- and S-wave velocities and fracture permeability were measured before and after laboratory-induced fracture alterations along with microstructural imaging through X-ray computed tomography and scanning electron microscopy. Our experiments show that S-wave velocity is an important geophysical observable, particularly the S-wave polarized perpendicular to fractures since it is sensitive to fracture stiffness. The acidizing and propping of a fracture both decrease its elastic stiffness. This effect is stronger for acidizing, and so it is possible that proppant monitoring will be masked by chemical alteration except when propping is highly efficient (i.e., most fractures are propped). However, fracture permeability is undermined by the softening of fracture surfaces due to acidizing, while greatly enhanced by propping. These contrasting effects on fluid flow in combination with similar seismic attributes indicate the importance of experiments to improve existing rock physics models, which must include changes to the rock frame. Such improvements are necessary for a correct interpretation of seismic velocity monitoring of flow pathways in stimulated shales.

Characterizing the borehole response for single-well shear-wave reflection imaging

Geophysics ◽  
2020 ◽  
pp. 1-42
Author(s):  
Yang-Hu Li ◽  
Xiao-Ming Tang ◽  
Huan-Ran Li ◽  
Sheng-Qing Lee
Keyword(s):  
Shear Wave ◽  
Wave Reflection ◽  
Spherical Wave ◽  
Dipole Source ◽  
Virtual Source ◽  
Shear Wave Imaging ◽  
Receiver System ◽  
Wave Imaging ◽  
Single Well ◽  
Reflection Imaging

Single-well shear-wave imaging using a dipole source-receiver system is an important application for detecting geological structures away from the borehole. This development allows for determining the azimuth information of the structures. Existing analyses, however, focus on the data received at the borehole axis and use the elastic reciprocity theorem to model the borehole radiation and recording. We extend the existing analyses to model the radiation, reflection, and the recording response of the borehole for azimuthally spaced receivers off the borehole axis. By treating the mirror image of the borehole source with respect to the reflector plane as a virtual source, the borehole reception problem is shown to be equivalent to the response of the borehole to the spherical wave incidence from the virtual source, which can be solved using the cylindrical-wave expansion method. An asymptotic solution using the steepest decent method is obtained if the virtual source is far from the borehole. The analytical solution allows us to analyze the borehole response for azimuthally spaced off-axis receivers. The analysis results agree well with those from 3D finite-difference simulations. With this analysis, one can further model the multi-component shear-wave reflection data from the cross-dipole acoustic tool and study the azimuthal variation characteristics of the data. The results show that, while the data characteristics are dominated by those of a dipole, non-dipole responses due to the off-axis reception can be observed, the magnitude of the responses depending on the off-axis distance and frequency and on the formation elasticity. The non-dipole response characteristics have the potential to resolve the 180°-ambiguity problem in the azimuth determination for the dipole shear-wave imaging. The findings, therefore, provide new information to the shear-wave reflection imaging analysis and development.

Identifying the lithology of volcanic rocks by using the time-frequency features of array acoustic logging data

2020 ◽  
Vol 8 (3) ◽  
pp. SL127-SL136
Author(s):  
Wenhua Wang ◽  
Pujun Wang ◽  
Zhuwen Wang ◽  
Min Xiang ◽  
Jinghua Liu
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Fractional Fourier Transform ◽  
Processing Method ◽  
P Wave ◽  
S Wave ◽  
Acoustic Logging ◽  
Time Frequency ◽  
Signal Processing Method ◽  
Component Wave

The traditional acoustic logging signal processing method is computing the slowness of each component wave by time-domain or frequency-domain methods. But both of the two methods are limited. To combine the signals’ times, frequencies, or amplitudes, we have analyzed the array acoustic logging signals by the fractional Fourier transform and the Choi-Williams distribution. First, we apply the fractional Fourier transform on an array acoustic logging waveform with proper [Formula: see text], then the Choi-Williams distribution analysis method is used to process the signal in the fractional Fourier domain, and finally the result will show in the fractional Fourier time-frequency domain. The results show the following. The array acoustic logging signal is received earlier in the mudstone and diabase formation than in the tuff and breccia formations. The basic frequencies of the compressional wave (P-wave) are not very different, but the basic frequency of the shear wave (S-wave) is highest in the tuff formation and is lowest in the diabase formation. The relative energies of each component wave in the diabase, mudstone, tuff, and breccia formation can be summarized as: for the P-wave, diabase > mudstone ≈ tuff ≈ breccia; for the S-wave, diabase ≈ mudstone > breccia > tuff; and for the Stoneley wave, diabase > mudstone > tuff > breccia. The signal processing method combining the fractional Fourier transform and the Choi-Williams distribution can comprehensively research the time, frequency, and amplitude, thereby improving the segmentation of the time and frequency domains and providing a new method for interpretation of array acoustic logging.

Estimating geomechanical parameters from microseismic plane focal mechanisms recorded during multistage hydraulic fracturing

Geophysics ◽  
2017 ◽  
Vol 82 (1) ◽  
pp. KS1-KS11 ◽  
Author(s):  
Wenhuan Kuang ◽  
Mark Zoback ◽  
Jie Zhang
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Principal Stress ◽  
Focal Plane ◽  
Amplitude Ratio ◽  
Horizontal Stress ◽  
Focal Mechanisms ◽  
P Wave ◽  
S Wave ◽  
Multistage Hydraulic Fracturing

We extend a full-waveform modeling method to invert source focal-plane mechanisms for microseismic data recorded with dual-borehole seismic arrays. Combining inverted focal-plane mechanisms with geomechanics knowledge, we map the pore pressure distribution in the reservoir. Determining focal mechanisms for microseismic events is challenging due to poor geometry coverage. We use the P-wave polarities, the P- and S-wave similarities, the SV/P amplitude ratio, and the SH/P amplitude ratio to invert the focal-plane mechanisms. A synthetic study proves that this method can effectively resolve focal mechanisms with dual-array geometry. We apply this method to 47 relatively large events recorded during a hydraulic fracturing operation in the Barnett Shale. The focal mechanisms are used to invert for the orientation and relative magnitudes of the principal stress axes, the orientation of the planes slipping in shear, and the approximate pore pressure perturbation that caused the slip. The analysis of the focal mechanisms consistently shows a normal faulting stress state with the maximum principal stress near vertical, the maximum horizontal stress near horizontal at an azimuth of N60°E, and the minimum horizontal stress near horizontal at an azimuth of S30°E. We propose a general method that can be used to obtain microseismic focal-plane mechanisms and use them to improve the geomechanical understanding of the stimulation process during multistage hydraulic fracturing.

Seismic imaging using microearthquakes induced by hydraulic fracturing

Geophysics ◽  
1994 ◽  
Vol 59 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Lisa V. Block ◽  
C. H. Cheng ◽  
Michael C. Fehler ◽  
W. Scott Phillips
Keyword(s):  
Hydraulic Fracturing ◽  
Wave Velocity ◽  
Seismic Imaging ◽  
P Wave ◽  
Basement Rock ◽  
S Wave ◽  
Fractured Zone ◽  
Wave Velocities ◽  
The Absolute ◽  
Wave Arrival

Seismic imaging using microearthquakes induced by hydraulic fracturing produces a three-dimensional (3-D), S-wave velocity model of the fractured zone, improves the calculated locations of the microearthquakes, and may lead to better estimates of fractureplane orientations, fracture density, and water flow paths. Such information is important for predicting the amount of heat energy that may be extracted from geothermal reservoir. A fractured zone was created at the Los Alamos Hot Dry Rock Reservoir in north-central New Mexico within otherwise impermeable basement rock by injecting [Formula: see text] of water into a borehole under high pressure at a depth of 3.5 km. Induced microearthquakes were observed using four borehole seismometers. The P-wave and S-wave arrival times have been inverted to find the 3-D velocity structures and the microearthquake locations and origin times. The inversion was implemented using the separation of parameters technique, and constraints were incorporated to require smooth velocity structures and to restrict the velocities within the fractured region to be less than or equal to the velocities of the unfractured basement rock. The rms amval time residuals decrease by 11–15 percent during the joint hypocenter-velocity inversion. The average change in the microearthquake locations is 20–27 m, depending on the smoothing parameter used. Tests with synthetic data imply that the absolute locations may improve by as much as 35 percent, while the relative locations may improve by 40 percent. The general S-wave velocity patterns are reliable, but the absolute velocity values are not uniquely determined. However, studies of inversions using various degrees of smoothing suggest that the S-wave velocities decrease by at least 13 percent in the most intensely fractured regions of the reservoir. The P-wave velocities are poorly constrained because the P-wave traveltime perturbations caused by the fluid-filled fractures are small compared to the amval time noise level. The significant difference in the relative signal-to-noise levels of the P-wave and S-wave arrival time data, coupled with the limited ray coverage, can produce a bias in the computed [Formula: see text] ratios, and corresponding systematic rotation of the microearthquake cluster. These adverse effects were greatly reduced by applying a [Formula: see text] lower bound based on the [Formula: see text] ratio of the unfractured basement rock.

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