bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using Factorial Design
Authors: Awoleke O. , Romero J. , Zhu D. , HIll A. D. 
Published: December 2012

Abstract
In this study we have undertaken a systematic investigation of the interactive effects of the key parameters that affect the final conductivity of a propped fracture, including flow back rate, proppant loading, polymer loading in the fracture fluid, the presence or absence of breaker, closure stress, and reservoir temperature. Fracture conductivity for conditions representative of field conditions was measured using a dynamic fracture conductivity testing procedure in which a fracture fluid/proppant slurry was pumped through a fracture conductivity cell, and then shut in and closure stress applied. Water-saturated gas was flowed through the fracture for a period of time at each closure stress to mimic gas flow back during the early stages of production. In all experiments, the proppant used was 30/50 mesh ceramic proppant. We used a fractional factorial design methodology to determine the relative importance of the fracturing parameters varied. The fractional factorial design method examines the combined effects on conductivity of potentially interacting parameters, while minimizing the number of experimental runs required.
The effects of the investigated factors arranged in order of decreasing impact on conductivity are closure stress, temperature, flow back rate, polymer loading, proppant concentration and presence of breaker. Increases in closure stress, flow back rate, temperature and polymer loading were observed to have deleterious effects on fracture conductivity. In particular, at high closure stresses and high temperatures, fracture conductivity was severely reduced due to the formation of a dense proppant- polymer cake. Dehydration of the residual gel in the fracture appears to cause severe damage to the proppant conductivity at higher temperatures. Also, at low proppant concentrations, there is the increased likelihood of the formation of channels resulting in high fracture conductivities.
Refining Discrete Fracture Networks With Surface Microseismic Mechanism Inversion and Mechanism-Driven Event Location
Authors: Cornette Brian M. , Telker Cherie , De La Pena Alejandro 
Published: December 2012

Abstract
Microseismic event analysis is a valuable source of information that can play a pivotal role in optimizing well completion and spacing. This analysis can be taken a step further with the generation of discrete fracture networks (DFNs) from microseismic events. While DFNs can be modeled with microseismic event locations only, source mechanisms inverted from near surface-acquired microseismic data provide greater constraints for the DFN model so that the orientation of failure planes responsible for events can be explicitly assigned. The differences between such DFN realizations based on event locations only and source-mechanism constrained DFN realizations are evident in areas with significant geological complexity.
Three iterations of a DFN model were produced from a microsesimic monitoring project in the Barnett shale. The fracture network of the first iteration is modeled stochastically using only basic geologic assumptions for the area and microseismic event locations and the orientations of trends formed by the events. The second iteration is refined by deterministically locating fractures in the model and defining the fracture orientations using a source mechanism determined from the microseismic point set. The third iteration uses the results from a mechanism scan on an event per event basis to determine the best source mechanism that fits the polarity reversal signature observed on the surface array.
Refining the model by determining the mechanism of individual events can identify multiple fracture orientations within the point set. In this data set two distinct mechanisms were identified, further analysis of which identified separate event energy distributions for the two mechanisms.
The changes in the model can be quantitatively evaluated with analysis of flow properties generated from the DFN and output to the stimulated reservoir volume (SRV). While changes in the SRV and total fracture volume for models presented in this study are most significant between the first two iterations, the total permeability change across the geocellular volume is significant between all three iterations.
Fracture Shadowing: A Direct Method for Determination of the Reach and Propagation Pattern of Hydraulic Fractures in Horizontal Wells
Authors: Daneshy Ali , Au-yeung Jessica , Thompson Trevor , Tymko Dean 
Published: December 2012

Abstract
This paper reports the results of field measurements carried out in four horizontal wells all of which were fractured in the course of this investigation, with a total of 68 fractures. The engineering basis for these measurements was detection of fracture shadowing (created by a combination of stress and pressure shadowing) created by the extending fractures. The results are used to develop a field-based engineering foundation for determination of fracture orientation and extent, spacing between wells, and the optimum number and spacing between fracture stages. Two of the four wells served as observation wells throughout the project while the other two were actively being fractured. Pressure gages were installed in each of the two observation wells.
Our findings show that we were able to detect fracture shadows generated by every stage of active fracturing. All the created fractures had a consistent northeast-southwest orientation, many were asymmetrical with respect to the wellbore, their propagation pattern was off-balance, and none of them intersected any of the many other existing fractures within the experiment domain. Some of the fractures had intersected and extended beyond the adjacent cased horizontal holes. The results also provided working approximations of the created fracture lengths.
A fortuitous coincidence of events allowed us to detect fractures created during the measurement period from another nearby well more than 1000 ft away. The fact that through fracture shadowing we were able to detect fractures so far away is quite remarkable. Furthermore, the general fracture growth pattern was consistent with the findings from the other four wells. The major advantage of the proposed approach is simplicity of operations, ease of analysis, and the high quality of results.
Modeling of Interaction of Hydraulic Fractures in Complex Fracture Networks
Authors: Wu R. , Kresse O. , Weng X. , Cohen C. , Gu H. 
Published: December 2012

Abstract
A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. Multiple fracture branches can propagate simultaneously and intersect/cross each other. Each open fracture exerts additional stresses on the surrounding rock and adjacent fractures, which is often referred to as "stress shadow" effect. The stress shadow can cause significant restriction of fracture width, leading to greater risk of proppant screenout. It can also alter the fracture propagation path and drastically affect fracture network patterns. It is hence critical to properly model the fracture interaction in a complex fracture model.
A method for computing the stress shadow in a complex hydraulic fracture network is presented. The method is based on an enhanced 2D Displacement Discontinuity Method with correction for finite fracture height. The computed stress field is compared to 3D numerical simulation in a few simple examples and shows the method provides a good approximation for the 3D fracture problem. This stress shadow calculation is incorporated in the UFM. The results for simple cases of two fractures shows the fractures can either attract or repel each other depending on their initial relative positions and compares favorably with an independent 2D non-planar hydraulic fracture model.
Additional examples of both planar and complex fractures propagating from multiple perforation clusters are presented, showing that fracture interaction controls the fracture dimension and propagation pattern. In a formation with small stress anisotropy, fracture interaction can lead to dramatic divergence of the fractures as they tend to repel each other. However, even when stress anisotropy is large and fracture turning due to fracture interaction is limited, stress shadowing still has a strong effect on fracture width, which affects the injection rate distribution into multiple perforation clusters, and hence overall fracture network geometry and proppant placement.
The Quest to Exclusive Use of Environmentally Responsible Fracturing Products and Systems
Authors: Brannon Harold D. , Daulton Daniel J. , Post Matthew A. , Hudson Harold G. , Jordan Andrew K. 
Published: December 2012

Abstract
Hydraulic fracturing processes have recently been the subject of increasing scrutiny with particular concern directed towards protection of water resources. Operators and fracturing services companies in the United States have been targeted by both federal and state legislators and the EPA with audits, inquiries, and regulations requiring disclosure of the chemicals pumped in fracturing treatments and banning the use of certain chemistries, such as diesel oil. Much effort has been expended to identify alternative, more environmentally acceptable products which maintain the needed material performance characteristics and cost basis.
A new quantitative process based upon the Globally Harmonized System for Classification and Labeling of Chemicals (GHS) has been employed to evaluate and rank the hazards posed by various treating fluid additives and potential alternatives. The GHS is a process is which has been adopted by the United Nations to standardize information regarding the hazards and toxicities of chemicals. Once the respective material hazards have been quantified, they may be ranked for comparison with like-purposed additives for their anticipated safety, health, and environmental impact. The best candidates by that measure may then be assessed for performance and cost. The process has become a valuable tool to guide fracturing R&D and oilfield chemical suppliers toward development of more environmentally acceptable products and systems.
The progress towards the objective of full implementation of environmentally acceptable chemistries in fracturing applications is documented. Working examples of the more acceptable chemical additive selections resulting from the applications of the hazard assessment process are provided. Furthermore, the migration to more environmentally responsible fracturing processes through quantification of hazardous risk "removed" from applications by replacement with more favorable alternatives is discussed.
The fruits of the process will be discussed in this endeavor, providing working examples of the chemical additive selection. Furthermore, the progress to more environmentally responsible fracturing processes through quantification of hazardous risk ‘removed’ from applications, i.e. amount of hazardous material removed by replacement with more favorable alternatives.
Proppant and Fluid Selection To Optimize Performance of Horizontal Shale Fracs
Authors: Penny Glenn , Zelenev Andrei , Champagne Lakia , Crafton James 
Published: December 2012

Abstract
The productivity and economics of horizontal wells are governed by the ability of the transverse fractures to communicate efficiently with the wellbore, which is strongly controlled by the conductivity of the proppant bed and the effectiveness of the fluid additives. These impact the relative permeability, the capillary pressure and the effective conductivity in the proppant bed. When time at temperature, stress cycling, embedment, multi-phase flow and non-Darcy effects are considered, the effective conductivity can be reduced 100-fold. Another investigated parameter is the impact of the wellbore location relative to the propagated fracture. If the wellbore is high in the fracture, gravity segregation will cause liquid removal from the lower portion of the fracture to be very difficult. In low conductivity proppant beds, capillary pressure will tend to retain high water saturations, thus lower conductivity even for the portions of the fracture above the wellbore.
Laboratory experiments have addressed these issues for proppants with a range of permeabilities from 10 to 100 Darcies; 100 mesh to 20/40 mesh and ceramics. The relative permeability to gas can be as low as 0.01, with as much as a 70-fold improvement when suitable proppants and additives are employed. Evaluation of the production performance of 240 wells, 98 with effective additives and 142 without, and covering a similar range of proppant types and sizes, shows a similar benefit to the wells’ normalized 30 day recovery and gross value. These results clearly demonstrate that economic expediency can be detrimental to a well’s ultimate value and hydrocarbon recovery.
Data Driven Modeling Improves the Understanding of Hydraulic Fracture Stimulated Horizontal Eagle Ford Completions
Authors: Shelley Robert , Saugier Luke , Al-Tailji Wadhah , Guliyev Nijat , Shah Koras , Godwin Jonathan 
Published: December 2012

Abstract
The subject of this paper is the results from a data driven modeling effort to derive best practices for the completion of hydraulically fractured horizontal Eagle Ford wells. The well, reservoir and production information used in this evaluation were provided by an operator, and are from a five county area in Texas consisting of Karnes, Gonzales, Atascosa, Dewitt and Live Oak.
Hydraulically fractured horizontal completions pose significant modeling and evaluation challenges. This is primarily due to two issues; 1) lack of well specific data about the reservoir/rock properties and 2) unrealistic assumptions used in the modeling process. As shown in this paper, a data driven approach to modeling these completions provides a much needed pragmatic perspective, identifies high impact parameters and provides direction about how to improve the effectiveness of these complex completions.
Sensitivities performed on the predictive model developed from Eagle Ford data indicate that well to well variation in reservoir quality and geology has a dominant effect on Eagle Ford production. In addition, issues such as fracture spacing, frac volume, perforation distribution, proppant selection and wellbore length also effect well production and economics. A ranking of controllable (Completion and Frac) and non-controllable (Reservoir and Geology) parameters that affect Eagle Ford production is included in this paper. This information can be used to derive best practices and is useful in explaining well to well variation in Eagle Ford production by quantifying the effect of reservoir quality, completion and frac methodology on results.
Engineering Guide to the Application of Microseismic Interpretations
Authors: Cipolla C. , Maxwell S. , Mack M. 
Published: December 2012

abstract
Microseismic monitoring (MSM) of hydraulic fracture treatments is routine in North America and has added significantly to our understanding of fracture growth. The interpretation of microseismic images is advancing steadily, extracting more information from event patterns, temporal evolution, and acoustic waveforms. The increasing amount of information from MSM provides significant opportunities to improve stimulation designs, completion strategies, and field development. However, the applications of microseismic interpretations are many times ill-defined, overlooked, or not applied properly. Numerous applications of microseismic measurements have been documented in technical publications, typically in the form of case histories focused on specific applications. The industry has lacked a compilation and comprehensive discussion of microseismic applications. This paper presents a practical guide for the engineering application of microseismic interpretations, documenting reliable application workflows while highlighting the consequences of misapplication of microseismic interpretations.
The application of MSM starts with a reliable interpretation of fracture geometry and complexity, but the real value is in the application of the interpretation. This paper divides microseismic applications into three categories, real-time, completion strategies & stimulation design, and field development. The MSM interpretation requirements for each category are documented and a comprehensive guide to properly applying these interpretations is presented. Applications issues such as determining the "effective" fracture surface area, the relationship between microseismic behavior and well performance, and fracture model calibration are addressed.
There is a growing interest in advanced processing such as moment tensor inversion (MTI) and b-values to determine focal mechanisms, source parameters, and failure mechanisms associated with the microseismic events. However, the engineering application of these interpretations is not well understood. This paper includes a discussion of the applications of advanced processing results, emphasizing how the limitations and uncertainties of the processing affect the subsequent applications.
Field Study Compares Fracture Diagnostic Technologies
Authors: Grae Abram D. , Duenckel Robert J. , Nelson Jordan R. , Smith Harry D. , Han Xiaogaag , Palisch Terry T. 
Published: December 2012

Abstract
Traditional proppant placement evaluation in hydraulically induced fractures utilize detection of radioactive (R/A) tracers such as iridium 192, scandium 46 and antimony 124, which are manufactured in nuclear reactors, and then shipped to the wellsite and pumped downhole with the frac slurry. Although this technique has proven useful, it involves environmental, safety, and regulatory concerns/issues. Recently a new technology has become available that offers a viable alternative to radioactive tracers. Field examples of the application of this technology and its usefulness to the operator are presented in this paper, along with a field comparison to the results from R/A tracers.
The new technology utilizes a non-radioactive ceramic proppant (CEP) that contains a high thermal neutron capture compound (HTNCC). This high thermal neutron capture compound is inseparably incorporated into each ceramic proppant grain during manufacturing in sufficiently low concentration so as not to affect proppant properties. The non-radioactive proppant is detected using standard compensated neutron and/or pulsed neutron tools, with detection based on the high thermal neutron absorptive properties of the proppant relative to downhole constituents.
Multiple zones in two wells in Wyoming were hydraulically fractured utilizing the non-radioactive detectable ceramic proppant. In addition, multiple zones in a well in Utah were fractured utilizing the non-radioactive detectable proppant and the results are compared to results from an R/A tracer utilized in another well in the same field. These field results and comparisons will aid the frac engineer in choosing appropriate proppant detection techniques.
Evaluating Horizontal Well Completion Effectiveness in a Field Development Program
Authors: Cherian Bilu V. , Stacey Edwin S. , Bressler Stephen , Iwere Fabian O. , Heim Robin Noel , Higgins-Borchardt Shannon 
Published: December 2012

Abstract
In field development programs where large variations in reservoir and completion parameters exist, the evaluation of reservoir performance to determine the optimal completion strategy can be a challenging task. This paper presents findings from a recent integrated cross-discipline analysis of a pilot program performed in the Bakken and Three Forks Formations (Williston Basin, North Dakota) to evaluate the impact of petrophysical and geomechanical properties on hydraulic fracture lengths, reservoir connectivity, well performance and well spacing.
Microseismic, geological, geomechanical, completions, engineering and production data were integrated in single and multi-well modeling approaches to provide an objective method to evaluate and compare well performance. Results and conclusions from various disciplines were validated by integrating operational observations with the modeling. The application of the proposed workflow allows one to (1) understand and evaluate the effect of fracturing parameters (length/conductivity) on well performance, (2) characterize reservoir and fracture properties using hydraulic fracture pressure and production history matching techniques (3) relate fracture parameters to reservoir, geology and mechanical properties and, (4) provide a methodology to understand key drivers controlling the development strategy of an asset.
Discrete Fracturing of a Deep, Unconventional Shale Play Using Multilateral Technology
Authors: Durst Doug G. , Vento Mario , Tucker Gary , MacDonald Mike 
Published: December 2012

Abstract
Drilling, completing, and fracturing unconventional formation wells in North America are now commonplace and will play a major role in the future of natural-gas production on which the nation will depend. What is not as common, however, is to drill, complete, and fracture multiple lateral branches from a single main wellbore. Multilateral wells have been routinely drilled for a number of applications, and shale plays are a natural progression for its use. Augmenting a multilateral well with selective fracturing of each leg is as straightforward as fracturing a single horizontal well.
Using conventional equipment and techniques, a multilateral well (with any number of laterals) can accommodate any type of fracturing system and program with pressures up to 12,500 psi and complete isolation of the lateral junction(s). In this project, a plug-and-perf system was used to address 10+ intervals in each leg, with average stimulation pressures up to 9,000 psi. By employing multilateral completion systems in unconventional wells, operators can lower drilling and completion costs, lower risk, help avoid non-productive time, reduce well count and surface footprint by combining two or more targets into one well, and maximize the net-pay-per-foot drilled ratio.
This paper will discuss the implementation and execution of this project as the first dual lateral well by any operator in the Granite Wash at vertical depths over 12,000 ft and measured depths reaching beyond 17,000 ft. This well targeted two different sections of the Granite Wash (a complex series of sands, shales, and siltstones that run from the Northern Texas Panhandle into Oklahoma) from a single main wellbore with commingled production rates doubling typical single horizontal well performance. Additionally, significant cost savings were achieved in contrast to drilling two separate single horizontal wells.