bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frac Hit Induced Production Losses: Evaluating Root Causes, Damage Location, Possible Prevention Methods and Success of Remediation Treatments, Part II
Authors: Rainbolt Michael F. , Esco Jacey 
Published: January 2018

Abstract
Millions of dollars in production losses are occurring from fracture-driven well-to-well interference (frac hits) in horizontal wells in unconventional play reservoirs. The work presented in SPE 187192 has been continued in this paper with a new case study (Case Study V), data from a pair of Wolfcamp B wells in the Permian Basin. The parent well suffered fracture interference during the child well's stimulation operations, negatively effecting production. The child and parent wells were both completed with the "plug and perf" technique. The parent well was completed with 74 stages while the child well's completion consisted of 105 frac stages. The child well was drilled with a longer lateral and the first 72 stages of the well's fracturing operations caused clear, repeatable pressure changes in the parent well. The data from these two wells is rich in cause and effect and permits compelling observations and conclusions. These findings were then compared to those from Case Studies I-IV, SPE 187192.
Detailed plots of the pressure changes superimposed with fracturing data were created and studied to better understand the significance and cause of what was happening to the Case Study V parent well. The shut-in pressure data from the parent well was taken at the intake of the electrical submersible pump (ESP) and recorded in 1-3 minute increments. Both wells have the same number of perf clusters per stage, stage spacing and amount of sand per stage. One-second fracture stimulation data for both completions was available. Case Study V plots and examples from Case Studies I-IV were put side-to-side and back-to-back to quickly view the similarities and differences. Fact-based conclusions were reached regarding causality of fracture-driven communication and interference between these wells.

Preface
The study for this paper is based on and uses data from nearly 200 individual fracture stimulation stages pumped in five pairs of wells. In order to document and discuss that much information, there are numerous plots and illustrations. While this is perhaps unconventional, it must be pointed out that a paper that is focused on data MUST show the data. Time constraints prevented the inclusion of several additional plots and "Part III" is being planned and is in the works. SPE 187192 (part I), King et al (2017) will be referred to several times and a few of the old plots are shown. There are new plots and observations from Case Studies I-IV.
Benefits of Engineering Fracture Design. Lessons Learned from Underperformers in the Midland Basin.
Authors: Parsegov S. G. , Niu G. , Schechter D. S. , Laprea-Bigott M. 
Published: January 2018

Abstract
Hydraulic fracturing (HF) is a very complex engineering process. It involves rock and fluid mechanics, mixed mode rock failure and transportation of individual proppant particles. This process is multiscale both in time and spatial domains that is why it is almost impossible to create a fully coupled 3D model with a detailed description of physical and chemical processes even with significant assumptions.
Recent data indicates well completion becomes more expensive than the drilling itself for several unconventional reservoirs. The reason is an increase of fluid and proppant pumped at high rates. Thus, the critical importance of engineering optimization of fracture spacing and individual pumping schedule for maximization of Net Present Value (NPV), Estimated Ultimate Recovery (EUR), and other metrics in the "lower for longer" price environment.
Unfortunately, unconventional operators see little value in fracture modeling because of its complexity and amount of data required for any reasonable predictive power. That is why many companies consider geometric design as the cheapest and hence the most efficient option thus resulting in trial and error to optimize HF design.
In this paper we use publicly available well logs and completion data covering the Midland Basin from the University Lands website. We also demonstrate that HF model calibration with microseismic data and stochastically generated Discrete Fracture Network (DFN), although is a challenging task, may improve our understanding of fracture design pitfalls and to become an essential step for optimum engineering design. Insights from our work can be useful to increase the predictive power of in-house models and reduce total cost and effort involved in this complex modeling.
Active Well Defense in the Bakken: Case Study of a Ten-Well Frac Defense Project, McKenzie County, ND
Authors: Bommer Peter A. , Bayne Marcus A. 
Published: January 2018

Abstract
The effects of well interference between existing producing wells and newly stimulated wells (commonly known as "frac hits") are of growing concern as full-density development accelerates across all the North American shale plays. Strategies to mitigate the negative effects of such interference are becoming increasingly important as frac hits become more frequent.
This case study presents a second-generation active well defense project involving four new wells and six offsetting legacy wells in the Bakken and Three Forks formations located in the North Fork Field, McKenzie County, ND. The operator has experienced numerous examples of stimulation interference in this field as its development operations have progressed into the full-density phase. Stimulation interference is defined as any increase in pressure occurring in a well as a result of stimulation activities in an offset or nearby well. While such interference has not necessarily had a lasting effect on legacy production, it has in some cases resulted in the need for costly remediation due to the migration of solids into the legacy laterals. The well defense efforts described herein are intended to minimize the need for post-stimulation remediation in legacy wells by preventing solids migration.
Mechanisms for the Formation of Complex Fracture Networks in Naturally Fractured Rocks
Authors: Shrivastava Kaustubh , Sharma Mukul M. 
Published: January 2018

Abstract
Complex fracture networks are formed when hydraulic fractures grow in naturally fractured reservoirs. Current planar fracture models are inadequate for capturing the effect of natural fractures on fracture propagation and addressing the important question of optimum fracture spacing and well spacing. Stress interference due to three-dimensional fracture networks can result in intricate fracture geometries, which are usually neglected by fracture models. In this paper, we present a three-dimensional hydraulic fracturing simulator that models the deformation and stress fields induced by both the dilation and shear failure of all existing and propagating hydraulic or natural fractures. It is shown that the simulator allows us to capture the complex fracture geometries, and microseismic signatures often observed in heterogeneous and naturally fractured rocks.
Fracture geomechanics is modeled in a computationally efficient manner using a fully three-dimensional displacement discontinuity method. The simulator captures the physics of fracture growth, fracture turning, fluid distribution in fracture networks, and the intersection of hydraulic fractures with pre-existing natural fractures. The model captures the interaction between multiple branches of a hydraulic fracture (stress shadow effect). The model also simulates the shear failure of hydraulically disconnected natural fractures to simulate microseismic activity and can account for the effect of shear failure and slippage along bed boundaries and along natural fractures on hydraulic fracture propagation.
The effect of pre-existing natural fracture density and orientation on the geometry of the fracture network generated is systematically studied. It is shown that natural fractures play an important role in determining the propagation direction of hydraulic fractures and this effect is quantified. At high natural fracture density, the propagation direction of a hydraulic fracture is dominated by the orientation of natural fractures rather than the far field stress magnitude and direction. The density of the natural fractures also affects the complexity of the final created fracture geometry.
An Engineered Approach to Hydraulically Fracture the Vaca Muerta Shale
Authors: Buijs Hernán , Ponce Jorge 
Published: January 2018

Abstract
In recent years, several papers have been published on the subject of rock properties, stress and permeability models in the Vaca Muerta unconventional formation, with the intention of understanding fractured well performance. In most cases, however, these publications have failed on providing sufficient information to adequately describe the generated models, nor have studied in detail the benefits and limitations of applying different schools of thought and incorporating field measurements during the design and evaluation of hydraulic fractures. This work seeks to explain a systematic approach to characterize, constrain and validate such models through integration of prefrac diagnostic injections, core data, independently-determined fracture dimensions, and postfrac production data. The final objective is to build predictive models that can be used to improve completion strategies in this promising but still immature play.
Optimization of Bakken Well Completions in a Multivariate World
Authors: Scanlan W. P. , Pierskalla K. J. , Sobernheim D. W. , Christian J. , Dutta R. , Sharma A. , Seigel S. , Zhang B. , Boykin B. 
Published: January 2018

Abstract
The advent of mega-sized hydraulic fracturing jobs which incorporate increased proppant per foot density, enlarged fluid volumes, tighter cluster spacing, and shorter stages in the Bakken/Three Forks play, have led to significantly higher IP's on the order of 20% over the past two years. Yet despite this dramatic increase, concerns exist as to whether treatments are fully optimized with respect to costs of overall volumes, rates, and concentrations. This paper describes two case histories, one in the Middle Bakken and one in the Three Forks formations of the Williston Basin, where a multidisciplinary geoscience and engineering team was assembled to attempt to answer the optimization question within the confines of real-world operational logistics and cost constraints.
In these case histories, an optimization process is described that begins with wellbore context. The consideration of offset wells in the area, data analytics processes considering reservoir quality, and perceived successful completions for the area are incorporated as input. Detailed layered and geomechanical models are then constructed using drilling, neural network and public domain data to produce optimized perforation cluster design and grouping in precise fracturing stages. A rigorous planar 3D hydraulic fracturing model is used to simulate fracture geometry characteristics including height growth, half length, and aperture. Lastly, proppant tracing and production modeling were used to validate the approach used.
The result of the project was to develop an optimization process incorporating the multidisciplinary technical team's expertise to provide an integrated, cost-effective completion design that would lead to more rigorous support for why these engineering decisions were taken. In addition, a secondary goal was to leverage software and database capacity for completion decisions into a "best practices process" that would neither burden the existing E&P staff nor hinder the completion timing. The resultant case study captures the process, technology analysis, weighted benefits, takeaway learnings, and results from two such wells within the Williston Basin.
A Summary of the US Environmental Protection Agency's Multiyear Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources
Authors: Dunn-Norman S. , Hufford W. , Almond S. W. , Consulting S. Almond 
Published: January 2018

Abstract
In December 2016, the United States Environmental Protection Agency (U.S. EPA) published the findings of their multiyear study entitled, "Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States." EPA's final report (with contributing studies) totals over a thousand pages, and sparked controversy during the assessment, after the release of their draft 2015 report and the final document. This paper provides a summary of the EPA study effort and processes, and highlights key finding and limitations of the work.
In 2010 Congress authorized the U.S. EPA to study the potential impact of hydraulic fracturing (HF) on water quality. EPA's office of Research and Development (ORD) drafted a study approach that included (1) defining research questions and identifying data gaps, (2) conducting a process for stakeholder input and research prioritization, (3) developing a detailed study design that would lead to external peer-review, and (4) implementation of the planned research. This study approach was reviewed by a committee formulated under the EPA's Scientific Advisory Board (SAB), and one author of this paper served on the first SAB review panel. A separate SAB committee was empaneled later to review the results of the research and draft conclusions. All three authors of this paper were appointed to the second SAB panel.
Initially, industry considered the Congressional request to be a focused assessment related to the actual process of HF on drinking water. It later became clear that the interpretation by the EPA of the Congressional request was a broader evaluation on the "life cycle" of water during the drilling and completion activities for oil and gas development. The final focused study approach was based on a HF hydraulic fracturing water cycle beginning with water acquisition, chemical mixing, and injection of the treatment. After HF (the actual hydraulic fracturing treatment, also known as "completion"), the fracture water cycle includes produced water handling, HF water disposal and reuse, and identification and hazard evaluation of chemicals across the hydraulic fracturing water cycle. Each of the stages in the HF process are treated separately in the study, and includes fundamental explanations, scientific research, academic (literature) review, and stakeholder input.
This paper provides a succinct summary of the EPA HF study. The summary is important for industry, government and academia as the final Assessment report is currently being cited as a basis for policy and regulatory development worldwide.
Production Performance of Infill Horizontal Wells vs. Pre-Existing Wells in the Major US Unconventional Basins
Authors: Lindsay G. , Miller G. , Xu T. , Shan D. , Baihly J. 
Published: January 2018

Abstract
In most US unconventional basins, operators often start development by drilling the minimum number of wells needed to hold their acreage. These initial wells are sometimes called "parent" wells. Operators then start drilling their infill development wells, which many operators are currently in the process of doing across various unconventional basins. Infill performance can be highly variable, with operators making great efforts to ensure infill wells perform comparable to or better than existing parent wells. This challenge will become more magnified in the unconventional industry as infill development surpasses parent well drilling. To add more uncertainty, limited research exists showing basin-wide trends as to how infill wells can be expected to perform on average in comparison to their parent well counterparts. We studied infill well performance in numerous US basins, with the objectives of understanding performance trends and their causes, along with providing recommendations for maximizing infill well potential.
We evaluated the performance of newly drilled infill wells compared to their parent wells, which had been produced for some time. With publicly available production and well information, an evaluation was performed for the following major unconventional basins: Bakken/Three Forks, Barnett, Bone Springs, Eagle Ford, Fayetteville, Haynesville, Marcellus, Niobrara, Wolfcamp (Midland and Delaware Basins), and Woodford.
Using a spatial, statistical approach with key production indicators, we identified key trends across the various basins where the infill wells produced at different production rates compared to their parent wells. Overall, there is about a 50% chance that a child well will outperform a parent well; However, normalizing production to total proppant pumped and lateral length suggests that larger volumes with longer laterals in infill wells may be needed to achieve similar rates to the parent wells.
Underperformance of infill wells may likely be because of existing depletion and inter-well production competition with both parent and other infill wells. Additionally, in areas where significant depletion is expected, predicting the performance of new infill wells can be very difficult. This paper will discuss alternative methodologies and technologies that may help understand and increase the production potential of lower performing infill wells.
Diagnostic Testing and Analysis of Hydraulically Fractured Dual-Porosity Formations
Authors: Elwaziry Y. , Soliman M. Y. 
Published: January 2018

Abstract
Several techniques were developed to analyze the after-closure fracture data of a DFIT/MiniFrac test. The majority of these techniques assume the reservoir is homogeneous. However, this assumption is not always satisfied: a formation may be heterogeneous and naturally fractured, making the published techniques not applicable in this case.
A most recent technique developed by Soliman et al. (2010) presented an analytical solution for an injection-falloff test for a naturally fractured formation. The solution was found to be effective, especially in the analysis of MiniFrac tests. However, the solution was applicable only in the absence of residual fracture conductivity.
A solution for an injection-falloff test for a naturally fractured and hydraulically fractured formation has been developed. The solution was established by inference using numerical simulation. MiniFrac tests are simulated and analyzed for naturally and hydraulically fractured formations. The study includes infinitely conductive fractures, finite conductivity fractures and radial flow regime.
Furthermore, the developed solution was employed successfully to analyze field data of a shale formation that is known to be naturally fractured. A naturally fractured formation that was hydraulically fractured is examined and presented.
Wavelet Analysis of Fracturing Pressure Data
Authors: Unal E. , Siddiqui F. , Soliman M. Y. 
Published: January 2018

Abstract
This study demonstrates a successful application of Wavelet Analysis to fracturing pressure data across various conventional and unconventional formations to evaluate post treatment data and enhance future stimulation practices. This methodology was compared to the proven Moving Reference Point (MRP) technique developed by Pirayesh et al (2013), to improve the understanding of wavelet analysis. As a fracturing diagnostic tool, the wavelet analysis technique can also be used as companion diagnostic tool alongside previously published methods (such as MRP etc.)
Wavelet analysis of a signal is the mathematical decomposition of that signal into orthogonal wavelet components. The level of decomposition is chosen to discern high and low-resolution parts of the signal. The process represents the signal as a sum of translations and scalings of the chosen wavelet to obtain coefficients of each wavelet.
Fracturing treatment pressure signals occur at various frequencies with finite durations that makes it possible to divide the pressure signals into many components and analyze them individually by wavelet transformation. Discrete Wavelet Transformation by Daubechie wavelets was implemented on fracture propagation pressure to various resolution levels to reveal necessary information within the data. The detail coefficients were analyzed by examining the anomalies at various resolution levels.
Wavelet analysis was performed on various shale and conventional fracturing data. Some interesting patterns are readily discernable from the wavelet detail coefficients. For instance, during the injection of proppants, there is an amplitude change in the detail coefficients at the exact moment when the proppant contacts the formation surface. This is expected because wavelet analysis is sensitive to any discontinuity in the system. Furthermore, such amplitude changes are also observed in the analyzed pressure data corresponding to tip screen-out and near wellbore sand-out events. Comparing such events along-side the MRP method paves the way for early detection of screen-out events. A comparison with the MRP technique is also provided in this study. This method reduces the uncertainty in analysis of Nolte-Smith and MRP method by providing an independent estimate of fracture propagation characteristics.
There have been publications discussing wavelet transformations of various formation and reservoir parameters (permeability, reservoir pressure, etc.), and discussing the application of wavelets for noise reduction and data smoothing. However, this is the first study mainly about wavelet analysis of fracture injection pressure data to understand and detect anomalies during various completion treatments. Ultimately, this technique helps to improve treatment designs and efficiency by analyzing fracture and formation behavior of the treatment and enhance decision making during execution, by providing early screen-out detections.
Measurements While Fracturing: Nonintrusive Method of Hydraulic Fracturing Monitoring
Authors: Parkhonyuk S. , Fedorov A. , Kabannik A. , Korkin R. , Nikolaev M. , Tsygulev I. 
Published: January 2018

Abstract
A new method of nonintrusive fracturing process monitoring in real time has been developed. The method is a combination of advanced signal processing algorithms and a tube wave velocity model based on Bayesian statistics and, thus, does not require complex hardware. This enables cost-effective and timely decisions at the wellsite. The technique was validated in the field in several fracturing and refracturing jobs.
Choosing the Right Products
Authors: Boothe M. , Videlock S. , Lincicome D. , Greaves R. , Hyden R. , Olson K. E. 
Published: January 2018

Abstract
The Right Products Program is designed to drive the assessment of all chemical products used in hydraulic fracturing through an effective decision-making process aimed at minimizing the toxicity of fracture fluids. This program increases the accountability of our chemical suppliers, improves HS&E stewardship, and reduces our overall impact potential from a human health and environmental standpoint. The Right Products Program provides an internal workflow through which all chemicals are reviewed to ensure that the safest and most appropriate products are used. In addition, the Right Products Program provides standards that chemical suppliers must meet prior to the product's use in operations.
This program demonstrates the commitment of Southwestern Energy (SWN) to do the right thing in order to responsibly develop our resources. The Right Products Program provides the ability to evaluate products company-wide through a consistent review process made possible by corporate, interdisciplinary, and operational collaboration.
This paper provides details behind the methodology of the Right Products Program. We will discuss the hazard assessment and product scoring, workflow, lessons learned, and provide examples of assessed products.