bluuebunny/crossref_metadata_2025 huggingface dataset:
Attitudes of Mental Health Professionals toward Mental Illness: A Deeper Understanding
Authors: Crowe Allison , Averett Paige
Published: May 2015

Because mental health professionals are not immune to negative attitudes toward adults with mental illness, researchers have questioned where these attitudes might originate, as well as what affects them. Although there have been quantitative studies that broadly explore attitudes toward mental illness, in-depth understanding of factors that affect the attitudes of mental health professionals will offer insight to practitioners and researchers alike. This qualitative study explored the impact of educational programs and professional experience on the attitudes of mental health professionals toward their clients. Based on the results, this article describes a continuum of attitudes toward mental illness for counselors, educators, supervisors, and related professionals as a tool to understand their attitudes toward mental illness.
Meta-analysis: Counseling Outcomes for Youth with Anxiety Disorders
Authors: Erford Bradley , Kress Victoria , Giguere Monica , Cieri Domenic , Erford Breann
Published: May 2015

This meta-analysis concluded that counseling and psychotherapy generally have a small to medium effect in treating anxiety in school-aged youth for termination (waitlist [k = 55;n = 2,959]d = .60[.52- .68]; placebo [k = 14;n = 867]d = .57[.42- .72]; treatment-as-usual [k = 10;n = 371]d = .32[.14- .50]; single group [k = 39;n = 889]d = .42[.37- .48]; and followup (waitlist [k = 22;n = 1,059]d = .51[.39-.63]; placebo [k = 2;n = 154]d = .73[.42-1.03]; treatment-as-usual [k = 9;n = 327] d=.21 [.02-.44]; single group [k = 36;n = 788]d = .58[.51- .65]). The findings of 80 clinical trials were synthesized using a random effects model for mean difference and mean gain effect size estimates. No effects of moderating variables were evident. Implications for counseling practice and future anxiety outcome research are addressed.
Counseling Military Veterans: Advocating for Culturally Competent and Holistic Interventions
Authors: Carrola Paul , Corbin-Burdick Marilyn
Published: May 2015

The large number of military personnel returning from combat operations in Iraq and Afghanistan with symptoms of mental illness has led to increased focus on specialized veteran mental health treatment and posttraumatic stress disorder. While this focus is both beneficial and warranted, it may lead to a myopic view of the experiences and needs of veterans. This article examines the responsibility of mental health professionals to balance the unique nature of veterans' experiences with their individual diversity rather than viewing them or their experiences through a strictly pathological lens. Failing to take a holistic approach to counseling each veteran may inadvertently stigmatize veterans as a group. The value of wellness counseling and the risks of over-pathologizing symptoms underscore the need to take a more diverse approach to counseling veterans and assist them with reintegration into their communities.
Detrimental Association: An Epistemological Connection of Dysfunction Within and Across Paradigms
Authors: Warren Jeffrey M. , Cottone R. Rocco
Published: May 2015

The notion of common factors in counseling and psychotherapy theory is not new. This article contends that detrimental associations are the root of dysfunction and are common to all theories of counseling and psychotherapy. The article defines detrimental associations as organic or auxiliary connections formed by clients that lead to dysfunction. Associations deemed detrimental include a variety of aspects of a client’s life, depending upon the theoretical lens through which dysfunction is viewed. The article explores how detrimental associations are conceptualized by level and across theories and paradigms and discusses implications for professional counseling.
Integrating Health and Wellness in Mental Health Counseling: Clinical, Educational, and Policy Implications
Authors: Barden Sejal M. , Conley Abigail H. , Young Mark E.
Published: May 2015

Few counselor training programs offer wellness courses or training on how to ethically and competently integrate physical and mental health issues when working with clients. This article highlights the interrelatedness of mental and physical health to build on the counseling profession’s own tradition of wellness and to encourage mental health counselors and counselor educators to adapt to changes in integrated healthcare. We propose that the mental health profession adopt competencies for wellness as part of standard counselor preparation and continuing education.
Evidence-Based Relationship Practice: Enhancing Counselor Competence
Authors: Sommers-Flanagan John
Published: May 2015

Defining mental health counselor competence is difficult. Unfortunately, professional definitions of competence often rely on abstract knowledge that is difficult for counselors to apply. This article highlights the history and terminology associated with the evidence-based movement in medicine, psychology, and counseling. Using this historical information as a foundation, a relationally-oriented, evidence-based practice model for achieving competence in mental health counseling is proposed. The model emphasizes such evidence-based relationship factors as (a) congruence and genuineness, (b) the working alliance, (c) unconditional positive regard or radical acceptance, (d) empathic understanding, (e) rupture and repair, (f) managing countertransference, (g) implementing in- and out-of-session (homework) procedures, and (h) progress monitoring. The purpose of the model is to articulate a distinctive and practical evidence-based approach that mental health counselors can wholeheartedly embrace.
Supervisors’ Suggestions for Enhancing Counseling Regulatory Boards’ Sanctioned Supervision Practices
Authors: Kress Victoria E. , O’Neill Rachel M. , Protivnak Jake J. , Stargell Nicole A.
Published: May 2015

Regulatory board-sanctioned supervision is intended to enhance the practice of disciplined counselor licensees and to protect the public. A qualitative research design was used to assess the perceptions of four supervisors who provided board-sanctioned supervision. The themes greater board-generated communication and ethics-related considerations were identified. Suggestions for state counseling regulatory boards are discussed.
Roles, Attitudes, and Training Needs of Behavioral Health Clinicians in Integrated Primary Care
Authors: Glueck Bethany P.
Published: May 2015

As integrated primary care (IPC) evolves, so does the new role of the behavioral health clinician (BHC). At present, mental health providers from various specialties are working as BHCs and adapting their training and skills to work as part of the medical team. The purpose of this qualitative study is to explore the experiences of BHCs who work in IPC so as to better understand their roles, attitudes, and training needs. The themes that emerged from semi-structured interviews suggest that the roles of a BHC are multifaceted and rooted in a holistic mind-body approach. Participants supported the need for additional training in graduate programs and internships for integrated care. The results informed a conceptual model of BHCs working in IPC.
Older Adults and Integrated Health Settings: Opportunities and Challenges for Mental Health Counselors
Authors: Goldsmith Jill S. , Kurpius Sharon E. Robinson
Published: May 2015

The growing number of older adults and the increasing recognition and growth of integrated health teams are creating expanded career opportunities for mental health counselors (MHCs). Collaborative integrated teams, staffed with medical personnel and MHCs, can provide comprehensive patient-centered care that addresses client issues from a biopsychosocial perspective. However, working with older adults on an integrated health team or in an interdisciplinary setting presents unique challenges and raises ethical issues. The evolving opportunities and strategies to address accompanying challenges are highlighted so that MHCs can be prepared to work effectively with older adults in interdisciplinary settings and on integrated health care teams.
Foam Production During Steam Displacement of Aqueous Surfactants
Authors: Michaels K. F. , Udell K. S.
Published: May 2015

The formation and flow of foam in porous media under conditions characteristic of steam injection were examined through a series of one-dimensional displacement experiments. It was observed that the steam front propagation velocity and temperature field ahead of and behind the condensation front were not significantly different for steam injection into partially saturated or dry media as compared to a water saturated medium. Significant differences in measured parameters were observed during steam displacement of a 1% by weight surfactant solution. The steam phase mobility decreased upstream of the condensation front by factors of 4.3 and 7.6 under conditions where noncondensable gases were not present and present as an initial gas saturation, respectively. These results clearly indicate that foam is produced during steam displacement of a surfactant solution without the presence of a noncondensable gas. Furthermore, noncondensable gas in the porous matrix was immobilized by the surfactant and aided in the stabilization of the foam in the steam zone.
A Comprehensive Application of a Composite Reservoir Model to Pressure Transient Analysis
Authors: Olarewaju J. S. , Lee W. J.
Published: May 2015

This paper presents analytical solutions for interpreting pressure transient tests for wells producing from a finite composite reservoir system. We also present rate solutions and methods for analyzing long term production data and forecasting production of oil or gas in a finite composite reservoir.

Composite reservoirs are reservoirs made up of two concentric zones of different hydraulic diffusivities. This type of reservoir consists of an inner and outer zone of uniform reservoir and fluid properties separated by a discontinuity. Composite systems include reservoirs with a fluid bank, reservoirs with a burning front, reservoirs with reduced permeability around the wellbore due to drilling fluid invasion and reservoirs with increased permeability around the wellbore due to acidizing or, as a good approximation, even fracturing.

This paper demonstrates that a composite reservoir model can be used to analyze wells with a high negative skin or wells intercepting a finite or an infinite conductivity hydraulic fracture. The differential equations for continuity of mass flow in the two regions are solved using Laplace transformation techniques for both the constant rate and constant pressure inner boundary conditions. The pressure solution is presented for a well in a finite or infinite-acting reservoir with wellbore storage effects. Both finite and infinite-acting reservoir solutions are presented for the constant pressure case. The paper demonstrates the behavior of pressure at the well located in the inner zone of the composite system with different permeability ratios of the inner and outer zone and different radii of the inner zone. Pressure and rate solutions are presented for different values of effective fracture permeability and effective fracture lengths. These type curves are equivalent to finite conductivity fracture type curves with wellbore storage effects included. The pressure and rate solutions for reservoirs with a fluid bank are also presented.

Dimensionless pressure and pressure derivative curves are presented with suitable parameters for type curve analysis. A step-by-step procedure for analyzing pressure transient data is presented. Permeability of the inner zone or the effective fracture permeability can be estimated. The radius of the inner zone which corresponds to an effective fracture length associated with the estimated effective fracture permeability, the radial distance of acid stimulation or the average radial distance of a waterflood front can be estimated. Forecases of production increase associated with varying effective fracture permeability and length can be made.

This paper presents three field examples to demonstrate the application of the type curve analysis method to buildup and falloff test data.
Successful Hydraulic Fracture Stimulation of Yoredale Carboniferous Sands in the UKCS
Authors: Jones Peter , Symonds Richard , Talbot David , Jeffs Paul , Kohok Abhimanyoo , Shaoul Josef , Spitzer Winston
Published: May 2015

The Breagh gas field lies in the UK Southern North Sea, 100 km east of Teesside in Blocks 42/13, 42/12a and 42/8a. The normally-unmanned gas field came on stream in October 2013 and is the first offshore development of the Yoredale formation of the Lower Carboniferous. The reservoir comprises a mixture of sand sheets and channels with permeabilities predominantly in the range 0.1 to 10 md.

The plan for the first phase of Breagh Field development was to drill 10 conventionally completed 65° angle deviated wells, through the reservoir, from a 12 slot platform. Analysis of log and PLT data from some of the initial wells identified channel sands, tighter than expected, yet containing significant GIIP. Wells 7 and 8 of the first phase of drilling were completed using hydraulic fracturing to evaluate the potential for improvement in productivity and drainage from the lower permeability intervals, although the execution of the stimulation programme brought significant challenges. This paper introduces the Breagh Field, discusses the reasons behind the change in completion design to include hydraulic fracture stimulation, considers the challenges associated with fracture placement in high angle wells and solutions implemented. The paper also addresses the importance of the clean-up phase, and reviews the lessons learned. In support of this programme, a number of hydraulic fracture designs and modelling methods were evaluated and used to make real time decisions during stimulation operations. These methods are discussed and used to estimate the value of hydraulic fracture stimulation in the Breagh field to date.

The first two wells to be stimulated on Breagh have been successful, yielding initial increases in productivity of the order of 4–10 fold. The magnitude of this increase has led to a forecast of significantly higher recovery from the lower permeability sands and from the total field. Important learnings from the subsurface characterisation, fracture planning and execution phases have been made. As a result of the success to date, hydraulic fracture stimulation is being integrated into the well completion planning and facilities design for the next phase of Breagh Field development.
Integrated Approach to Managing Formation Damage in Waterflooding
Authors: Aristov Sergey , van den Hoek Paul , Pun Eddie
Published: May 2015

Waterflooding is the most widely used secondary recovery concept in the oil industry. Once embarked on, it becomes vital to assure the proper planning and execution of a project. There are multiple examples of things that can go wrong if the project is not properly designed, and/or if the practices and standards are not adhered to. These include loss of injectivity, out-of-zone injection, early water breakthrough, loss of reservoir containment, significant CAPEX/OPEX overruns, injector-producer shortcircuiting, reservoir souring and scaling issues etc. Understanding of formation damage is one of the overarching themes in a waterflood project. It requires an integrated multi-disciplinary approach to conclude on an optimum design and strategy. Some of the issues that need to be addressed in the first place are: - matrix of fractured regime; - injectivity decline and necessary water quality specifications; - fracture growth over time and its impact on sweep; - risk of out-of-zone injection and loss of reservoir containment.

Realising the magnitude of these questions, Shell has developed a suite of tools to tackle these issues and help in adequate designing and optimization of waterfloods. They include:

– ASCET (Actual and Simulated Coreflood Evaluation Tool). On-site coreflood tests at real-life conditions, measuring formation impairment as function of water quality. – FORDAM (FORmation DAMage) software. Estimation of injectivity decline when no ASCET tests are available. – PWRI-FRAC (Produced Water Re-Injection FRACture modelling). Quantification of fracture growth as a function of water quality and injection rate. – FRAC-IT (FRACture IT). Model the impact of fracture growth. Assess risk of out-of-zone injection and impact on sweep.

Utilising these tools helps make informed waterflood decisions, improve water management, reduce (or eliminate) water disposal, lower environmental impact, avoid unnecessary CAPEX/OPEX.
Thermally Stable Brine-Based Drill-In Fluids
Authors: Zha Weibin , Galindo Kay , Zhou Hui , Deville Jay P.
Published: May 2015

Reservoir drill-in fluids are specifically designed to avoid excessive fluid penetration and solid invasion into production zones so as to minimize formation damage. With wellbore temperatures increasing, the drive to develop thermally stable drill-in fluids has increased dramatically over the last few years. Oil-based or synthetic-based drill-in fluids can meet temperature requirements easily, but are often not desirable for drill-in applications. Brine-based drill-in fluids usually use bio-based polymers as viscosifiers, but they are not suitable for high temperature applications because most bio-based polymers break down at temperatures above 300°F. Most synthetic polymers available in the market are difficult to hydrate in concentrated brine solutions, and they are not so thermally stable because of hydrolysis, especially when the temperature is above 350°F. This paper describes the application of two uniquely developed polymers in brine-based drill-in fluids that demonstrate outstanding performance at temperatures greater than 400°F.

Polymer 1 is designed to work with monovalent brines, and polymer 2 is intended for divalent brines. Using these two polymers, thermally stable, brine-based drill-in fluid formulations were prepared with densities ranging from 10.5 to 18 ppg. Various brine and weighting agent combinations were investigated to keep the total amount of solids low for the various fluid densities tested. Calcium carbonate (CaCO3) was used as a bridging and weighting agent for low density fluids, and manganese tetroxide (Mn3O4) was used for high density fluids. All fluids were prepared using a multimixer, and the fluid viscosity was examined with a direct-indicating viscometer. Return permeability testing was conducted on both a lower permeability Kirby sandstone core and a higher permeability Berea sandstone core.

Both polymers provided very good rheology and solid suspension capability, as well as very good fluid loss control. The drill-in fluids made with these two polymers were statically aged at 400°F for 72 hours after conditioning the fluid by hot-rolling for 16 hours at 150°F. The viscosity of the fluids was well maintained after aging, and the high temperature (350°F/500 psi) fluid loss was less than 15mL and 10 mL for polymer 1 and polymer 2, respectively. The thermally stable brine-based drill-in fluids demonstrated high return permeability values, indicating minimal formation damage on the tested cores.

High temperature brine-based drill-in fluids are limited by the availability of thermally stable viscosifiers and fluid loss control additives. The newly developed polymers 1 and 2 provide thermal stability up to 400°F for 72 hours, which has not been achieved with previous bio-based polymers or other synthetic polymers.
Advanced Residue-Free Fracturing Fluid with Improved Friction Reduction and Exceptional Cleanup Properties
Authors: Singh Dipti , Russell Aaron , Schnoor Eli , Inyang Ubong
Published: May 2015

Conventional guar borate systems have historically been preferred for hydraulic fracturing applications because of the lower cost of the base polymer and crosslinker. Additionally, the fluid formulations can be easily tailored based on reservoir conditions and operational needs and the favorable tubular friction reducing characteristics of guar-based fluid systems makes them a desirable option for fracturing fluid systems. However, water insoluble residue resulting from guar-based systems may significantly impact the permeability of the proppant pack when flowing back and producing the well. A recently developed, nearly residue-free (RF) fluid system offers excellent cleanup properties and, as a result, has provided significantly improved production of hydrocarbons compared to typical guar-borate systems. While offering excellent performance and production, the RF fluid demonstrated significantly less friction reduction than comparable guar-based systems. This paper introduces a newly developed fluid system offering equivalent cleanup properties and performance, but with significantly enhanced friction reduction. The lower friction of the (LF)-RF system helps lower wellhead pressures to allow maintaining pump rate, adhering to the job design, to place the desired amount of proppant in the fracture.

This newly developed LF-RF fluid is a high performance fracturing fluid with improved regained conductivity and core permeability cleanup compared to typical guar-borate crosslinked systems. It is applicable within a wide variety of reservoirs, including unconventional reservoirs, and to-date has been successfully used in more than 1,100 stages since its introduction in early 2014. The LF-RF fluid system is applicable from 100 to 275°F bottomhole static temperature (BHST) and offers excellent operational versatility and proppant transport. This paper compares fluid performance and friction response of a conventional guar-borate fluid and the existing RF system with the newly developed LF-RF fracturing fluid.
Captain Field Injector Performance, Historical Perspective and Recent Improvements
Authors: Jones Colin , Ross Mike , Getliff Jonathan , Fuller Michael , Hiscox Ivan , Mandracchia Francesco
Published: May 2015

The Captain Field is situated in the outer Moray Firth in approximately 340ft water depth. The reservoirs are shallow sandstone, either sheet turbidite or channel sands. The oil is relatively viscous and is drained using long horizontal wells. The reservoir is sub hydrostatic and uses either electrical or hydraulic submersiblepumps for artificial lift.

Produced water re-injection supplemented by the field aquifer is used for voidage replacement and to maintain reservoir pressure above bubble point. The water injectors are long horizontal wells with one injector supporting a number of producers. The sand is unconsolidated and injectors are generally completed with stand-alone screens.

Since drilling the first injector well in 1995 there has been an evolution in drilling and completion practices and while the original wells were drilled with non-aqueous drilling fluids, current wells are drilled with water based fluids that have been optimized over the years. This has been an iterative process with the aim of reducing formation damage and increasing baseline injectivity.

Screen type and stimulation techniques have also changed over time and later platform wells have also been flowed back to surface which tends to greatly improve the initial injectivity. This improved injectivity is critical for the success of future field development and enhanced oil recovery deployment, which initially requires drilling of new subsea injectors. However flowing a subsea injector back to a semisubmersible rig involves significant safety and operational issues, thus new methods of increasing injectivity are being sought.

This paper will present the history of the Captain Field's injectors, explain the lessons learned over time and describe the ongoing studies that are being performed to better understand the damage mechanisms to ultimately eliminate the requirement for flowing back injector wells.
Mathematical Modelling of Non-Uniform External Cake Profile in Long Injection Wells
Authors: Kalantariasl Azim , Farajzadeh Rouhi , You Zhenjiang , Bedrikovetsky Pavel
Published: May 2015

Injection of colloids and suspensions in natural reservoirs accompanied with particle capture and external cake formation results in well injectivity decline. External filter cake build-up followed by stabilization is a well-known phenomenon in several engineering fields. Significant decline of the tangential rate along large intervals in long vertical wells yields non-uniform external filter cake profile. We derive the mechanical-equilibrium equations for the stabilized cake profile accounting for electrostatic particle-rock interaction and varying permeate factor. Torque balance is applied to cake equilibrium criterion and the lever-arm ratio is calculated using Hertz's theory for contact deformation of cake and particles. An implicit formula for the cake thickness along the well is derived. Two regimes of the stabilized cake build-up correspond to low and high injection rates, respectively. If the rate is below the critical value, the external cake is built up in the overall injection interval. If the rate is above the critical value, there is no cake in the upper part of the wellbore; the cake starts at the depth where the tangential rate reaches the critical value. The sensitivity analysis shows that the drag and permeate forces are the competitive factors affecting cake thickness under varying Young's modulus, rate and salinity. The main parameters defining external cake profile are injection rate, cake porosity, water salinity and Young's modulus.
New Insights into Fracturing Fluid Additives and Their Interaction in Shale Outcrop Cores Using NMR Techniques
Authors: Kim Jihye , Gomaa Ahmed , Zhang Boyang , Qu Qi , Nelson Scott , Zhang Hao
Published: May 2015

Oil and gas productivity from shale formations can be dependent on the flow behavior of the hydraulic fracturing fluids used in stimulation treatments. Because of the unique characteristics of shale formations, including low permeability, existence of micro-fractures, and sensitivity to contacting fluids, it is difficult to evaluate the complex microscopic interactions occurring between the fracturing fluids and the reservoir rock using traditional laboratory methods. Therefore, the objective of this study is to evaluate the interaction between fracturing fluid and representative shale cores by quantifying the invaded fluid volume during the treatment and shut-in time as a function of pore geometry using nuclear magnetic resonance (NMR) technology.

Shale outcrop cores from the Eagle Ford, Barnett, Marcellus, and Mancos were evaluated in this study. Cores were submerged in various fracturing fluids under pressure and temperature for two days. The increase in the volume of the fluid invaded into the cores was quantified using NMR as a function of the average pore radius. To mimic the flowback recovery process, the cores were placed in a vacuum cell for an hour, and the decreased fluid volumes within the cores were measured. Test conditions in this study investigated the effects of clay control additives and surfactants. Furthermore, the effect of operating parameters such as the pressure and fracturing fluid contact time was investigated.

NMR techniques enable the effective evaluation of additives, such as surfactants and clay control additives, which until now may have been selected solely based on best practices established from stimulating local conventional formations. Additionally, this comprehensive fluid evaluation technology supports the creation of customized fracturing fluids, targeted for individual shale formations, to maximize factors such as post-fracturing load recovery, and to aid in the advancement of the industry's understanding of new fracture modeling concepts.
The Impact of Formation Damage on Core Quality
Authors: Byrne Michael , Zubizarreta Izaskun , Sorrentino Yelitza
Published: May 2015

Formation Damage caused during drilling can have a significant impact on the near wellbore and the ability for a well to deliver to design. The reduction in near wellbore permeability is generally interpreted as a negative and the damage is normally minimised through careful selection of fluids, drilling methods and parameters. The focus on formation damage usually comes during development well planning, where optimum productivity or injectivity are required. Formation damage can also have an impact on core quality when cores are being cut and recovered to surface.

Good quality core is valued by Formation Evaluation and indeed, formation damage specialists, as it enables direct measurement of rock and fluid properties on real samples of real reservoir. It is well known that core retrieved too quickly from reservoir to surface can be physically damaged by “gas expansion”. Previous work has demonstrated that gas expansion damage should only be a major issue in low permeability reservoirs (Zubizarreta, 2013; Hettema, 2002). However, higher permeability reservoir cores can also be damaged (Worthington, 1987; Holt, 1994).

Consider the core surface and a few milimeters in to the core – mud cake and damage occur. The permeability of damaged zone is significantly lower than reservoir rock. In gas reservoirs or when bubble point is reached in high GOR, core retrieval leads to pressure difference across the damaged zone and desaturation of the mud cake damaged zone. If this pressure difference exceeds strength of rock then a thin layer of damaged rock material may develop. This fracturing of the core can render it useless for many of the normal laboratory tests conducted on core.

This paper will present evidence of structural damage developed due to formation damage around reservoir core. We will also present the modeling method used to predict this damage and give some examples of core tripping out schedules designed to protect the valuable core resource. The impact of formation damage on core structural integrity will be explored in detail for the first time and the method presented can be used to predict and avoid structural damage in future coring operations.
Acid Zone Coverage for Long Horizontal Well Stimulation Challenges and Field Case Study
Authors: Nino-Penaloza Andrea , Li Xiaohe , Gomaa Ahmed M. , Chaudhary Saleem
Published: May 2015

Success in matrix acid stimulation of carbonate formations depends largely on the acid distribution and the created wormhole length. Treatment design is still as much art as science, especially where field experience is used to quantify the design parameters for candidate wells. However, each well is different, and this generic approach for treatment design can result in under- or over-treating. Another challenge for long horizontal well matrix acidizing is the distribution of acids throughout a long horizontal well. Recently, controlling the perforation density and distribution has been implemented in long horizontal well matrix acidizing and proved successful in improving well productivity. This approach basically involved pumping acid through a perforated work string inside a large open-hole area. The acid distribution with limited entry into the surrounding a horizontal well is mainly controlled by perforation distribution around the work string.

In this paper, a fluid placement simulator is used to study the key parameters in optimal acid distribution with this novel limited-entry technique in long horizontal well matrix acidizing. The algorithm is based on a 2-D radial flow system that iterates time to quantify wormhole propagation and injection rate. Wormhole velocity is calculated by a laboratory empirical model that depends on two parameters measured from core flow testing. Therefore, the algorithm captures the essential physics and chemistry of the acid reaction in a carbonate porous medium. Also, this model includes such effects as multiple formation layers with independent formation parameters and allows for modeling zonal coverage, zone skin factor, and total skin factor. The main difference in terms of the improvement of formation damage from both openhole and this limited-entry completion is investigated.

The developed algorithm is a relatively simple tool that can be used by field engineers to design and optimize an acid treatment, addressing key questions such as: What type of acid and what strength should be used? What are the optimum acid volume and pump rate? What are the best diversion method and staging design? This paper demonstrates the key issues related to the interaction between the wormhole model and zonal coverage. In addition, different scenarios and a field case example are presented and discussed.
Numerical Study of Fracture Cleanup Effects and Optimization of Post-Fracture Production
Authors: Han Jiahang , Yang Junjie , Sookprasong Andy , Lafollette Randy
Published: May 2015

Gel damage has been identified as the most severe damage effect on gel-fractured well productivity. The reduced effective fracture length and fracture conductivity can significantly decrease the initial production rate and the ultimate recovery, especially for tight reservoirs. In this paper, we conduct numerical studies on fracture cleanup effects, and explore procedures for improving post-fracture production.

To effectively simulate fracturing fluid rheology and transportation, a dual continuum method is employed in our model. Gel residue inside the fractures is determined based on gel and breaker reaction dynamics from experimental data. Increased gel concentration in slurry injection, increased breaker concentration during fracture clean-up, and the flowback procedure are simulated to quantify the gel damage phenomenon. Features such as non-Darcy flow through fractures and polymer adsorption/desorption are included in the model. Parametric studies on the gel and breaker concentrations, reservoir properties, and flowback designs are also discussed.

Our studies determined that interactions between breaker and gel can be fully integrated into numerical simulations. Tested with a variety of gel and breaker concentrations as well as the reaction dynamics, the numerical model is robust in quantifying the gel damage phenomenon in the fracture. Detailed numerical evaluations of gel damage effects with severe gel-damage zone inside the fracture are demonstrated in this paper. High gel residue concentration is observed at the tip of fractures due to high yield stress during flowback, which reduces the effective fracture drainage. Cleanup efficiency is highly dependent on the gel and breaker interactions. Based on parametric studies, optimized gel/breaker concentrations and sufficient interaction time can significantly reduce the gel residue inside the fracture and provide possibilities of having less gel damage in hydraulic fractures. The results provide new observations about improving well productivity through proper gel/breaker selection and flowback design.
Determining the Optimum HF Concentration for Stimulation of High Temperature Sandstone Formations
Authors: Abdelmoneim Sherif S. , Nasr-El-Din Hisham A.
Published: May 2015

Over the years, sandstone acidizing has experienced low success rate. This makes it essential to develop a systematic method for selecting the optimum hydrofluoric acid (HF) concentration, which can achieve the highest possible permeability enhancement. Field experience and experimental studies show the significance of HF acid concentration in controlling the outcome of the treatment: adding too much HF acid will result in secondary and tertiary reactions damaging the reservoir while the use of low concentrations of HF will result in insufficient dissolution. The objective of this study is to investigate the effect of HF acid concentration and design a systematic method for designing sandstone-acidizing treatments.

Experimental work was designed to investigate the effect of the HF acid concentration, and identify the optimum concentration for different sandstone formations. Two types of sandstone cores were used in this study: Grey Berea which is characterized by low carbonate content (3 wt%), and Bandera which has a high carbonate content (16 wt%) and high content of troublesome minerals (10 wt% illite). Coreflood experiments were performed on 6 in. cores with 1.5 in. diameter. Temperatures of 280 and 325°F were used for the experiments to address the moderate and high temperature applications. HF acid concentrations varied from 0 to 3 wt% HF. Optimum concentrations were selected based on the ratio of permeability improvement. Inductively coupled plasma (ICP) was used to measure the concentrations of key ions in core effluent.

The experimental results proved the relationship between the acid concentration and mineral content. At the temperature of 280°F, Grey Berea cores, with clay content of 8 wt% and 3 wt% feldspars, the HF concentration of 1.5 wt% was able to achieve the best results. For the Bandera cores, which have a clay content of 14 wt% (10 wt% illite, 1 wt% chlorite, 2 wt% kaolinite) and 12 wt% feldspars, the acid that achieved the best results contained 1 wt% HF. When temperatures were increased to 325°F, permeability enhancement was significantly decreased while the optimum concentration remained fairly at the same HF concentration. This proves that the optimum acid concentration is independent on the temperature, but for high temperatures (>300°F) retarded acids should be considered.

This work introduces the concept of designing acid treatments as a function of the mineral content. The optimum concentration of the HF was proven to adopt an inverse relationship with the mineral concentration. The proposed relationship can be used to determine the optimum acid concentration required for sandstone stimulation.
Formate Drilling & Completion Fluids: Evaluation of Potential Well Productivity Impact, Valemon
Authors: Fleming Niall , Moland Lars G. , Svanes Grete , Watson Russell , Green Justin , Patey Ian , Byrne Michael , Howard Siv
Published: May 2015

Valemon, operated by Statoil, is a HPHT gas/condensate field on the Norwegian Continental Shelf. Production started at the end of 2014 from a development consisting initially of cased & perforated wells. However, during early field development the orginal concept had been for stand alone screens (SAS) lower completion. K/Cs formate water based system with a density of 2.02sg. was considered as a candidate drilling and completion fluid for the wells completed with screens, one of which could potentially be suspended in formate brine for up to 10 months prior to the arrival of the platform and before clean up and the onset of production. An unknown was the possibility for any near wellbore interaction with these fluids during extended contact and the possible detrimental impact on productivity that this could have. Computational fluid dynamic (CFD) modelling was performed to determine how long formate would be in contact with the near wellbore and this demonstrated that, especially for the lower permeability intervals, a contact time of approximately 45 days was a possibility. In light of this, a sequence of corefloods was performed involving extended soaks in formate along with pre- and post test analyses to identify potential damage mechanisms. Those identified included kaolinite dissolution, precipitation of Barsium and cesium silicate, and swelling of kaolinite due to the incorporation of potassium and cesium into the kaolinite lattice. To confirm the findings from the CFD and coreflood modelling, a field review was made of Statoil's experiences with suspending wells for extended time in formate prior to clean up and production. The field review demonstrated positive experiences in using formates in suspended wells with respect to productivity. Lower than expected productivity was experienced for some wells but this could not be conclusively related to use of formates. The paper provides an overview of lessons learned from coreflooding, CFD modelling and actual field data on wells suspended in formate prior to clean-up and production.
Experimental Study of the Permeability Damage Associated with Fines Production from a Bituminous Coal during Water Injection
Authors: Guo Zhenghuai , Hussain Furqan , Cinar Yildiray
Published: May 2015

Coal seam gas (CSG) production involves water flow through coal cleats. Creep effect and fines migration can cause a severe damage to coal permeability during water flow. This study presents a systematic methodology to analyze coupled effect of creep and fines migration in a water injection test in a coal sample. Previous studies investigating permeability changes in coal during water flow do not incorporate both of these effects.

We perform two flow tests on coal samples from a mine in China. Proximate, petrographic and XRD tests were conducted for a robust characterization of the coal sample. The coal samples are saturated with ultra-pure water. Afterwards, the same water is injected through the saturated coal sample. The test temperature and injection pressure was kept constant during the flow and production rate was measured continuously to calculate permeability. Fines concentration of the produced water samples was tested by a laser particle counter. Afterwards, the produced fines were separated from the water samples using micron membrane filters. The separated fines were then analyzed using SEM-EDX method. The only difference in two tests procedure is that in first test, the sample is mounted in a Hasseler coreholder under 300psi confining stress while the second test is done under zero confining stress. This allows us to remove any creep effects in the 2nd test while the first test results are affected by both creep effect and fines migration.

The samples in this study are characterized to be bituminous coal containing mainly kaolinite and dolomite in mineral matters. The permeability is reduced to 10% and 73% of the original value in the first and second test, respectively. Although, creep effect is more pronounced as compared to fines migration effect, the 2nd flow test results demonstrate significant permeability damage during the water injection through the coal samples, along with appreciable fines production. The produced fines appear mainly in form of a mixture of coal and clay minerals. The strain associated with the creep effect in the first test contributes to a relatively high fines production as compared to the second test.
New Innovative Process for Underbalanced Drilling Candidate Screening
Authors: Qutob Hani , Byrne Micheal
Published: May 2015

Underbalanced drilling technology (UBD) has increased production potential from many oil and gas reservoirs worldwide. When UBD succeeds, it works wonders; Discovering hidden production zones, improving drilling by eliminating lost circulation and differential sticking, increasing rate of penetration, improving production by reducing formation damage, and providing real time reservoir evaluation. The result is Enhanced Oil Recovery and Improved Net Present Value.

Yet too often, UBD fails to live up to its potential either because unsuitable reservoirs are drilled or inappropriate drilling technology is applied. The key to selecting appropriate reservoir candidates for UBD is achieving a balance of technical, safety and economic factors.

Recognizing the growing need for better predictive tools to drive improved outcomes, an expert system was developed. The system is a process that uses Computational Fluid Dynamics (CFD) to enable detailed modeling of fluids in wells and the surrounding reservoirs. CFD is the study of the dynamics of things that flow.

The use of the expert system to screen and select candidate reservoirs for the UBD and MPD applications enables accurate prediction using detailed numerical models of flow in the reservoir, damaged zone and the wellbore. These predictions reveal the actual benefits of Underbalanced and Managed Pressure Drilling in well productivity and increased well recovery through the reduction of formation damage.

This innovative expert system has been used in more than 40 projects for some of the world's leading oil and gas projects across UK, Western and Eastern Europe, Scandinavia, Middle East and Asia. Users of this system recognize that near wellbore fluid flow modeling using CFD will become standard industry practice. This paper describes in detail the expert system and presents the successful application and several case histories and real results.
Formation Damage in Tight Gas Reservoirs
Authors: Qutob Hani , Byrne Micheal
Published: May 2015

The increased demand for more sources of clean energy such as natural gas from unconventional reservoirs has forced the industry to explore the more challenging tight gas reservoirs. Tight gas reservoirs constitute a significant proportion of the world's natural gas resource and offer great potential for future reserve growth and production. However, to meet future global energy demand, access to tight gas reservoirs requires innovative and cost effective technical solutions.

Yet, tight gas reservoirs are often characterized by complex geological and petrophysical systems as well as heterogeneities at all scales. Exploring and developing tight gas accumulations are both technically and commercially challenging due to the large subsurface uncertainty and low expected ultimate recovery per well. In addition, formation damage is an undesirable operational and economic dilemma that may occur during any phase of gas recovery from tight gas reservoirs. Tight gas reservoirs normally show significant damage during well drilling, completion, stimulation and production. Therefore, they may not flow gas at optimum rates without advanced production improvement techniques.

The main damage mechanisms and the factors that have significant influence on well productivity in tight gas reservoirs include mechanical damage to formation rock, plugging of natural fractures by mud solid particles invasion, relative permeability reduction around wellbore as a result of filtrate invasion, liquid leak-off into the formation during fracturing operations, water blocking, damage due to wellbore breakouts, compression damage and the damage associated with perforation. Drilling and fracturing fluids invasion mostly occur through natural fractures and may also lead to serious permeability reduction in the rock matrix that surrounds the natural or hydraulic fractures.

Prevention, control and remediation of formation damage are among the most important issues to be resolved for efficient exploitation of tight gas reservoirs. Designing certain chemicals and/or treatment procedures for damage control and remediation is not an easy scientific and engineering task. Good understanding of the formation damage mechanisms would allow operators to make informed decision as to the best practices to drill, complete and produce tight gas wells.

In this paper, a review of commonly practiced methods and tools available for prevention, control and remediation of formation damage will be discussed and presented.