bluuebunny/crossref_metadata_2025 huggingface dataset:
Condemning Self, Condemning Other: Blame and Mental Health in Women Suffering Stillbirth
Authors: Cacciatore Joanne , Frøen J. Frederik , Killian Michael
Published: May 2015

Every year around the globe there are more than two million stillbirths, yet stillbirth is generally treated as a non-event, considered less impactful than the death of a live-born child. In up to 60 percent of third-trimester stillbirths, the causes of death were attributed to maternal conditions or were "undetermined." As a result, mothers blame themselves or specific others. This analysis set out to determine how the attitudes of 2,232 bereaved mothers predict their mental health outcomes measuring depressive and anxious symptoms with the Hopkins Symptom Checklist (HSCL). Of the women sampled, 24.6% reported blaming themselves, and 42.3% reported elevated HSCL mean scores. Self-blame in particular is correlated with symptoms of anxiety and depression. Multivariate analyses predicting elevated HSCL scores demonstrated the importance of time after death, level of education, and reported abuse during pregnancy in the models, as did self-blame and blaming others. Controlling for other demographic and pregnancy-related variables, self-blame was the strongest predictor of poor mental health outcomes. Implications for mental health counselors are discussed.
Interactive Journaling as a Clinical Tool
Authors: Miller William R.
Published: May 2015

Spoken language is the primary medium of counseling and psychotherapy. The therapeutic value of written language has also been studied extensively, both to provide self-help information and to elicit personal reflection. Interactive journaling (IJ) is a guided writing process that combines both of these functions. It has differed from usual therapeutic writing in two ways: (a) by integrating the presentation of treatment-relevant information in graphic-enhanced text to engage the reader, and (b) by offering frequent structured opportunities for the client to respond to and integrate material being presented. This article provides a description and the first review of research on IJ as a clinical tool. Experimental and quasi-experimental evaluations support a link between IJ and behavior change. Research on motivational interviewing offers evidence-based guidelines for structuring IJ materials to elicit language favoring change, as well as testable hypotheses linking writing processes with outcomes. Implications for counseling practice and research are considered.
STRENGTH: A System of Integration of Solution-Oriented and Strength-Based Principles
Authors: Davidson Tim
Published: May 2015

The STRENGTH acronym denotes a systematic approach to the integration of solution-oriented and strength-based counseling principles and provides a mnemonic for mental health counselors, counselor educators, and students. Foundational ideas from leading theorists and practitioners in various strength- and solution-oriented therapies are organized under representative letters of the acronym. Checklists to assess the focus of counseling sessions are part of the model. The acronym is a practice tool to guide the counselor in promoting positive, collaborative change strategies that emphasize client strengths rather than clinical pathology.
Integrated Primary Care: Why You Should Care and How to Get Started
Authors: Vogel Mark E. , Malcore Sylvia A. , Illes Rose Anne C. , Kirkpatrick Heather A.
Published: May 2015

Many mental health practitioners who are interested in primary care may not know how to get involved. Integrated Primary Care (IPC) is a model that normalizes mental and behavioral health issues in primary care with the goal of improved health outcomes; it shows promise for addressing mental health care disparities. Recognizing that mental and physical health problems are interwoven, utilizing the primary care system of medical health delivery offers an opportunity for patients to have greater access to behavioral services. Recent movements have increased the demand for integration of physical and behavioral health. This article reviews research on access issues, adherence, and the effectiveness of IPC with particular attention to newer studies and those examining culturally diverse groups. Finally, it offers suggestions for counselors seeking to integrate their practice with the primary care setting in a culturally sensitive way.
Cultural Competency, Culturally Tailored Care, and the Primary Care Setting: Possible Solutions to Reduce Racial/Ethnic Disparities in Mental Health Care
Authors: Kohn-Wood Laura P. , Hooper Lisa M.
Published: May 2015

Racial and ethnic minorities in the United States are less likely to receive treatment for psychiatric disorders than are White Americans. For two decades, clinicians and researchers have worked to reduce health and health care disparities, with at best minimal success. In 2001 the Surgeon General issued a seminal report that described the magnitude of the problem (U. S. Department of Health and Human Services, 2001). Nevertheless, the vexing problem of unequal treatment persists. This review provides preliminary evidence for reducing racial and ethnic disparities in mental health treatment in primary care settings by giving priority to culturally competent practices and cultural tailoring in assessment, diagnosis, and treatment.
Variables Associated with High Caregiver Stress in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: Implications for Providers in a Co-Located Memory Assessment Clinic
Authors: Hall Daniel , Wilkerson Joseph , Lovato James , Sink Kaycee , Chamberlain Dana , Alli Rabeena , Clarke Philip , Rogers Samantha , Villalba José , Williams Julie , Shaw Edward G.
Published: May 2015

Caregiver burden—the stress associated with caring for a loved one with chronic illness—is rated as high or very high by about two-thirds of Alzheimer’s caregivers. At Wake Forest School of Medicine, both patients with memory loss or cognitive impairment and caregivers are evaluated at a geriatrician-led co-located Memory Assessment Clinic (MAC). In a sample of 100 MAC-evaluated patient-caregiver dyads this study assessed both patient severity of Alzheimer’s disease or other dementia, self-reported behavioral disturbances, degree of functional independence in general activities of daily living and instrumental activities of daily living (IADLs), and caregiver stress as measured by the Caregiver Burden Scale (CBS). Several patient factors were found to be related to high caregiver stress (CBS score > 25), in particular moderate-severe dementia; inability to perform most IADLs, especially managing medications; and most behavioral disturbances, especially agitation/aggression and appetite/eating problems. The article also suggests ways medical and mental health providers and researchers can help reduce caregiver stress.
A Qualitative Exploration of Fear and Safety with Child Victims of Sexual Abuse
Authors: Foster Jennifer M. , Hagedorn W. Bryce
Published: May 2015

Although child sexual abuse (CSA) is a pervasive societal problem that is estimated to affect 1 in 4 girls and 1 in 6 boys before the age of 18 (Centers for Disease Control and Prevention, 2005), little is known about CSA from the perspective of the victims themselves. To address this gap in the research, this study used a narrative approach to explore children’s perceptions of their abuse experiences. Analysis of 21 narratives written during Trauma-Focused Cognitive Behavioral Therapy revealed a meta-theme, which was entitled Fear and Safety. Children’s descriptions of past and current fears and concerns about their safety and the safety of others were evident in all 21 narratives. The article delineates counseling interventions that mental health counselors can use to target fear and enhance safety.
Paruresis: What Counselors Need to Know about Assessment and Treatment of Shy Bladder Syndrome
Authors: McGraw Michael S. , Rothbaum Gina L. , Sterner William R.
Published: May 2015

Paruresis, considered a category of social phobia, is the fear of being unable to initiate or sustain urination in the presence of others or in situations where others may become present. Many clients who struggle with paruresis present with symptoms commonly associated with other types of social phobia, which makes assessment, diagnosis, and treatment difficult. Although paruresis is relatively common, many counselors know little about it. This article focuses on the prevalence, etiology, course, assessment, diagnosis, and treatment of paruresis. Case scenarios are presented to guide counselors in assessing and diagnosing paruresis. Implications for counselors are discussed.
Effectiveness of Cognitive Processing Therapy for Treating Posttraumatic Stress Disorder
Authors: Lenz Stephen , Bruijn Brian , Serman Nina S. , Bailey Laura
Published: May 2015

Analyzing 11 studies, we evaluated the effectiveness of cognitive processing therapy (CPT) for treating posttraumatic stress disorder (PTSD) and co-occurring depression symptoms in individuals diagnosed with PTSD. Separate meta-analytic procedures for between-group studies using waitlist or alternative treatment comparisons yielded large to very large effect sizes for CPT versus waitlist, and medium to large effect sizes when CPT was compared to alternative treatments. Implications for evidence-supported practice and study limitations are discussed.
The Use of Mind-Body Practices in Counseling: A Grounded Theory Study
Authors: Nichols Lindsey
Published: May 2015

In U.S. culture, there is increasing interest in using complementary therapies (CT), which the National Institutes of Health also refer to as complementary and alternative medicine (CAM). In clinical mental health counseling, there has been little research on CT use, though there is potential for CT practices to illuminate perspectives on professional identity, ethical practices, and responsiveness to client needs. This grounded theory study examined the use of CT by 16 professional counselors across the United States to increase understanding of how and why practitioners use CT. The findings revealed four key categories that delineate the use of mind-body practices in counseling: (a) experiences with CT; (b) beliefs creating openness to CT; (c) development of CT competence; and (d) reinforcement of CT use in professional practice. Implications for exploring CT in clinical counseling are discussed (see also Nichols, 2012).
Indirect effects of sea otters on rockfish (Sebastes spp.) in giant kelp forests
Authors: Markel Russell W. , Shurin Jonathan B.
Published: May 2015

Sea otters are a classic example of a predator controlling ecosystem productivity through cascading effects on basal, habitat‐forming kelp species. However, their indirect effects on other kelp‐associated taxa like fishes are poorly understood. We examined the effects of sea otter (Enhydra lutris) reintroduction along the west coast of Vancouver Island, Canada on giant kelp (Macrocystis pyrifera) distributions and the trophic niches and growth of two common kelp forest fishes, black (Sebastes melanops) and copper (S. caurinus) rockfishes. We sampled 47 kelp forests, and found that red sea urchins (Strongylocentrotus franciscanus) were eliminated in the presence of otters, and that kelp forests were 3.7 times deeper and 18.8 times larger. Despite order‐of‐magnitude differences in kelp forest size, adult black and copper rockfishes contained less kelp‐derived carbon in their tissues (as measured by stable isotopes of C and N) in regions with otters. Adults of both species had higher mean trophic positions in the presence of otters, indicating more frequent consumption of higher trophic level prey such as fishes. Smaller trophic niche space of rockfishes in the presence of otters indicated a higher degree of trophic specialization. Juvenile black rockfishes rapidly shifted to higher kelp‐carbon contents, trophic positions, and body condition factors after settling in kelp forests. The relationships of growth to length, percentage of kelp carbon, and trophic position varied between the two regions, indicating that potential effects of kelp forest size on trophic ontogeny may also affect individual performance. Our results provide evidence that the indirect effects of otters on rockfishes arise largely through the creation of habitat for fishes and other prey rather than a direct trophic connection through invertebrates or other consumers of kelp productivity.
Air Stripping for Treatment of Produced Water
Authors: Fang C. S. , Lin J. H.
Published: May 2015

In a laboratory study, air stripping shows a promising potential for treatment of produced water to meet the new government regulations on total organic carbon. Reservoir hydrocarbons dissolved in water, such as volatile paraffins and aromatics, can be removed by air stripping through interphase mass transfer. However, air stripping can not remove many chemicals added to crude oil by the operator.
Mechanisms of Residual Oil Displacement by Steam Injection
Authors: Stewart L. D. , Udell K. S.
Published: May 2015

A model of one-dimensional steam displacement of residual oil has been developed. The quasi-steady model considers the capillary pressure gradients due to the simultaneous flow of the oil, water, and steam to be the dominant factors in oil bank mobilization. The effects of gravity on steam displacement were also included in the model. Semi-analytical calculations of saturation and pressure distributions are presented to illustrate the mechanisms.

It was shown that under most conditions, the Buckley-Leverett displacement velocity is significantly faster than the steam condensation front velocity. This result and conservation of oil mass required the use of the steam condensation front velocity as the characteristic velocity in the problem formulation. An expression for a limiting oil saturation at the steam zone interface was thus derived.

Experiments were conducted to examine steam displacement of volatile, partially volatile and nonvolatile nonaqueous phase liquids at a residual saturation of 2.5%. Complete displacement of all low viscosity, partially volatile liquids was observed. Displacement of a high viscosity, nonvolatile oil was not observed. These experiments were in reasonable agreement with the model.
The Kern River Horizontal-Well Steam Pilot
Authors: Dietrich J. K.
Published: May 2015

The Kern River vertical shaft and horizontal well steam pilot was designed and installed on the basis of a geological model which emerged from analysis of numerous closely spaced wellbore drilled on the 25-acre test site. Numerical simulation was used to develop both the strategy for stemflooding operations performed at the test site during the period 1982–1983 and the projections of long-term process performance.

Eight horizontal wellbores spaced at 45-degree increments were rotary-drilled into the base of the heavy oil column (18 to 20 degree API) from a 500-foot vertical shaft positioned at the center of the 25-acre rectangular pilot area. The original concept was to use only horizontal wells for cyclic steaming and steamflooding operations; this concept was modified on the basis of simulation results which indicated the potential for early steam breakthrough and poor capture efficiency of the displaced oil. The modification involved drilling conventional vertical wells (one well within each of the eight sectors formed by the horizontal wells) and injecting steam into them while producing from the horizontal wells (Figure 1).

The pilot was terminated because of unfavorable economics after recovering 2-1/2 percent of the oil-in-place. The oil recovery rate and process efficiency were each improving at the time the pilot was abandoned. Early sluggish oil response was predicted and observed owing to low vertical permeability and extensively depleted oil saturation and pressure conditions which exist at the pilot site. Long-term pilot operations were shown to be capable of recovering significantly more oil at equivalent OSR than that expected from conventional steamflood development.
Effects of Shutting in Injectors on Steamflood Performance
Authors: Hong K. C.
Published: May 2015

The effects of temporarily shutting in steam injection wells on oil recovery by steamflooding were studied using a steam injection simulator. Both heavy and light oil steamflood situations were considered. One-eighth of a five-spot models representing the two types of reservoirs were employed to study the effects of shutting in the injector for up to eight months on the oil production performance during the shut-in period as well as following the resumption of steam injection.

The simulation results show that temporarily shutting in injectors is not detrimental to overall oil recovery. For each type of reservoir (heavy or light oil) the cumulative oil production at a limiting instantaneous steam-oil ratio of 10 was essentially the same regardless of the length of injector shut-in. The cumulative steam-oil ratio at the end of the project life also remains the same regardless of the length of shut-in. Shutting in the injector, however, prolongs the project life, increasing it by about the length of shut-in for the heavy oil and by more than the length of shut-in for the light oil case.

This paper compares oil production performances for steamflood projects operating under different shut-in scenarios, and recommends strategies to cope with changing economic environment.
Eliminating Formation Damage by Underbalanced Coiled Tubing Drilling - A Field Case History from Hungary
Authors: Wesemann Mark , LeClair David
Published: May 2015

Formation damages caused by the invasion of drilling and workover fluids into the near wellbore area can become a major threat for production. Over the last decades, several techniques have been developed to mitigate this issue in terms of mud cake removal and wellbore stimulation to either dissolve or bypass the damage created. However, the most promising and efficient way would be the elimination of fluid invasion in the first place by underbalanced drilling. Therefore the applicability of this approach in a reservoir located in Hungary will be demonstrated in the following.

The paper reports the challenges as well as the final success of the well Öscöd Eny 1, which was nearly completely lost, until it was recovered by non-damaging Coiled Tubing Drilling.

Due to severe wellbore control issues while conventionally drilling into an over pressured horizon, the well had to be partly cemented to shut of the intense gas influx. Coiled Tubing as the ideal tool for live operations was then used to firstly mill out this cement and secondly deepen the unfinished wellbore significantly into the pay zone – both underbalanced.

Based on the great operational success of this procedure and the impressive production results of a nearly lost wellbore, it was decided to apply this method in an optimized overall procedure for future wells, as it was faster, cheaper and most importantly not damaging to the formation, leading to significantly improved production.

All in all, this paper provides an insight into a successfully applied technology to eliminate formation damage in a Hungarian Gas Field, which led to a rethinking about how to drill and complete these reservoirs in a cost effective and non-damaging way.
40 Years of Low-Salinity Waterflooding in Pervomaiskoye Field, Russia: Incremental Oil
Authors: Akhmetgareev Vadim , Khisamov Rais
Published: May 2015

Low-salinity waterflooding (LSW) and its effect on oil recovery factor have been studied around the world during the last 30 years. Low-salinity/fresh water was used in the initial stage of waterflooding because of deficiency of produced water. The Pervomaiskoye oil field in Republic of Tatarstan is one of the examples. Waterflooding started in 1966. Water was taken from the nearest water source, the Kama River. After more than 40 years, about two PVI has been injected, and 30.1% of this injected water was low-salinity.

This paper presents the results of laboratory study of double core flooding using high-salinity (formation) and low-salinity (river) water. Two plugs were taken with the clay content of about 0.8% and 0.1% and the permeabilities of 432 and 291 mD, respectively. Dead oil was used with the viscosity of 37.5 mPa.s. TDS values were about 252,738 ppm for high-salinity water and 848 ppm for low-salinity water. Dry and vacuumed plugs were saturated, first, with high-salinity water, then, with oil, to simulate connate water saturation; then, oil was displaced with the same water. After this, the cores wre restored to the connate water by a secondary oil flood, and finally, LSW was simulated. In both cases, oil recovery was recorded and fines release was analyzed.

Processing of the low-salinity corefloods data by a numerical model shows a two-fold decrease of water relative permeability for the first plug and 1.5 times reduce of residual oil saturation for the second plug. Fines release and formation damage was observed in the first plug and wettability alteration in the second plug. Oil relative permeability didn't change. Also, the unusual behavior of water relative permeability in response to low-salinity waterflood was observed, namely, it decreased at water saturation values more than 0.4.

To investigate the low-salinity EOR effect seven pilots on the Pervomaiskoye field were analyzed, with high-salinity waterflooding following LSW. Incremental oil recovery for these pilots, that has been achieved by now, is approximately 5-9%. Calculations of low-salinity EOR effect in the field show that LSW through 96 injectors ensures to date the incremental recovery factor of 3-4%.

The reservoir 3D model of five-spot pattern for the Pervomaiskoye field for fines-assisted waterflooding gave incremental oil recovery by 5-11%. The laboratory relative permeabilities were used in the model. Incremental oil recovery depends on the number of the flooded layers.
Development of a Novel Methodology to Identify Seawater Breakthrough Onset and Understand Formation Damage Caused by BaSO4 Scale Deposition - History Match of North Sea Wells
Authors: Chen Tao , Marinou Eugenia , Chalmers Frances
Published: May 2015

Waterflooding with seawater is the most common approach to supporting reservoir pressure and stimulating oil production in offshore installations. However, producing wells can be significantly damaged when seawater breakthrough occurs, as BaSO4 scale can deposit in the near wellbore area; especially for wells with formation waters containing a high concentration of barium ions.

Different ion monitoring and analysis methods are traditionally used to calculate the percentage of seawater breakthrough, with varying levels of accuracy and reliability. This presents a significant challenge, as accurate determination of seawater breakthrough, especially at its onset, is critical for scale management and selection of appropriate mitigation strategies.

This paper discusses the development of a simple methodology for seawater breakthrough determination in a North Sea field, using reactive ions. Unlike other approaches, the method calculates the percentage of seawater breakthrough through the balancing of the seawater breakthrough as determined from individual reactive ions; it also allows the determination of BaSO4 mass deposition downhole, corresponding BaSO4 mass stripped in the deep reservoir and amount deposited in the near wellbore.

The relationship between oil production rate and percentage of actual seawater breakthrough has been correlated based on matching well historical data. The different stages of formation damage as a function of increasing seawater breakthrough are also presented. Last, the difference between the contribution of BaSO4 stripped in deep reservoir and deposited in the near wellbore on and its impact on formation damage is discussed.

This paper presents a comprehensive study of monitoring and calculating seawater breakthrough using a robust and accurate methodology. Seawater breakthrough and the relationship between downhole scale deposition and formation damage have been correlated using real field data. Combined with scale predictions, it is proposed that this approach can enhance scale management strategies and thus optimise oil production. The method is applicable to any oilfield using seawater flooding, rendering it a significant tool in optimising oil production and minimising well downtime.
New Laboratory Method to Assess Formation Damage in Geothermal Wells
Authors: You Zhenjiang , Badalyan Alexander , Yang Yulong , Carageorgos Themis , Schacht Ulrike , Bedrikovetsky Pavel , Hand Martin
Published: May 2015

The new method to assess permeability damage in geothermal reservoirs and predict well productivity decline is presented. The laboratory methodology developed aims to determine permeability decline from mobilisation, migration and straining of natural reservoir fines. Laboratory coreflood testing with constant and stepwise decreasing ionic strength has been performed with measurements of the pressure drop along the core and accumulated effluent particle concentration. Stabilisation of rock permeability occurs after injection of numerous pore volumes, suggesting slow drift of mobilised particles if compared with the carrier water velocity. Low ionic strength water increases electrostatic repulsion forces between clay particles and sand grain surfaces, further mobilising particles and resulting in formation damage. Kaolinite and illite/chlorite mixed layer clay minerals are identified by SEM-EDAX analysis and are the minerals primarily responsible for the permeability damage. The competitive effects of decreasing water viscosity and weakening electrostatic attraction on the attached particle concentration during temperature increase have been observed. The micro-modeling of the fine particle mechanical equilibrium shows that the water viscosity effect on the fine particle attachment dominates. It results in decreased fines detachment and permeability decline at high temperatures.
A New Fracturing Fluid for HP/HT Applications
Authors: Zhao Haiyan , Nasr-El-Din Hisham A. , Al-Bagoury Mohamed
Published: May 2015

Hydraulic fracturing is used extensively to develop oil and gas wells in both high and low-permeability formations. Biopolymer-based fluids, including guar or guar derivatives, constitute the majority of polymers in fracturing fluids. These polymers cause formation damage, which is a serious problem on production enhancement. Therefore, the search for an alternative to guar is meaningful to the oil industry. In this paper, a novel viscosifier (V1) was developed to prepare fracturing fluids.

The rheological properties and proppant suspending ability of V1-based fluid have been studied with the effects of viscosifier concentration, temperature, and salts. Formation damage of the new type of hydraulic fracturing fluid in sandstone has been evaluated and compared to guar, hydroxypropyl guar (HPG), and viscoelastic surfactant (VES) fluids. The effects of temperature, viscosifier type, concentration, and formation permeability were investigated. The regained permeability of sandstone cores (expressed as a percentage of the initial permeability) was used to quantify the damage degree in coreflood tests.

The viscosity measurements have shown that V1-based fluids were stable up to 350°F with a high tolerance to KCl and CaCl2. Moreover, V1-based fluids had a good proppant suspending ability at 75 and 250°F, which out-performanced guar-based fluids. Coreflood tests were run using Berea and Bandera sandstone cores. As for V1 fluids, the regained permeabilities of the cores were 88% or higher of the initial permeabilities, suggesting that V1 caused a slight damage. However, guar and HPG fluids caused much more damage than V1 fluids under same conditions. The effects of temperature, viscosifier concentration, and formation type were different for guar-based fluids from V1 fluids. The external filter cake was formed when the V1 fluid was injected; however, no external filter cake was found for guar, HPG, or VES. The filter cake could be removed by injecting 5 wt% KCl brine in the opposite direction.

It was the first time to use this new cellulosic viscosifier in hydraulic fracturing fluids. The new type of fracturing fluid has better thermal stability and proppant suspending ability than guar-based fluids under the same conditions. Moreover, high regained permeability of sandstone cores can be maintained when treated by the new fracturing fluid.
Halite Envelope for Downhole Salt Deposition Prediction and Management
Authors: Zhang Yuping , Isaj Elisabeta
Published: May 2015

Halite salt deposition in the near wellbore formation and the wellbore of a gas well can dramatically reduce its productivity within a very short period of time. In order to minimise the salt induced formation damage, it is essential to identify if, where and how much halite will be deposited. The main objective of this work is to develop an easy- to-use tool for downhole salt deposition risk assessment and management.

The main mechanism for halite deposition in the near wellbore formation and the wellbore of a gas producer is water evaporation at a reduced pressure. A high deposition risk is expected at a high drawdown and a low produced formation water to gas ratio (FWGR). Halite deposition can also occur at a reduced temperature or pressure due to reduced halite solubility in water. A halite envelope can be used to determine the downhole halite deposition risk, which is a boundary marker for the start of halite deposition at which point halite is saturated in water. Two types of halite envelopes are introduced in this paper. One is for different reservoir pressures at differing FWGRs and but at a fixed temperature. The second is for different temperatures at differing FWGRs at a given reservoir pressure.

A number of North Sea gas field halite deposition cases will be presented in this paper. Each case will illustrate how the halite envelope technique can be used to identify high risk wells; their salt free operating conditions or to determine the requirement for water washes, and their associated injected water volumes. It will also demonstrate that for its successful application, reliable measurement of the water and gas production, along with an understanding of the water/gas influx, are both prerequisites in the validation of a halite envelope.
Efficient Proppant Flowback Prevention Strategy Allows Production of a Multi Fractured Offshore Horizontal Well Equipped With ESP and Screenless Completion
Authors: Martocchia Francesco , Dirya Ahmad D. , Baretti Salvatore , Farina Lisa , Rizza Giovanni , Okassa Fabrice , Haaland Tor G.
Published: May 2015

When production facilities are not equipped with a solid control device, proppant flowback becomes an issue throughout the entire productive life of a screenless multi fractured well. The challenge of minimizing proppant flowback is even more critical when dealing with offshore horizontal wells with ESP systems installed.

A wide selection of proppant flowback prevention additives is now available in the industry: most of them work either chemically or mechanically. At low formation temperature (150 F), the effectiveness of some additives such as resin coated proppant or fiber can be limited due to the temperature activation.

This paper will describe a successful strategy of proppant flowback control which was implemented in a multi stage fracturing treatment on a horizontal well in M- field, offshore Congo. It is the combination of resin coated proppant, enhanced by a chemical activator and inert fibers that provides double mechanism to eliminate proppant flowback issues during well production and sustaining life of ESP.

Success in this multi stage fracturing treatment has resulted in oil production from a pay zone that has never been produced due to poor petrophysical characteristics.

This document will describe: proppant flowback control additives selection process, placement strategy, hydraulic fracturing design and well execution considerations for multi stage fracturing treatments.
Controlling Excessive Water Production Using Induced Formation Damage
Authors: Zeinijahromi Abbas , Bedrikovetski Pavel
Published: May 2015

Excessive water production is one of the major factors in wells’ productivity reduction. It can be resulted from water coning and water channeling from water table to the wells through natural fractures, faults or high permeability zones. The use of foams or gels for controlling water production has been tested successfully in several field cases. However A large treatment volume is required to block the water influx that generally involves high operational and material costs. It is well know that injection of low salinity water into reservoir can mobilize reservoir fines and significantly decrease reservoir permeability. This paper presents the possibility of applying induced formation damage in order to block the water influx without hindering the oil production. This is a new cost-effective method using injection of low salinity water slug. It is shown that system of equations for water injection with induced fines migration and polymer injection is mathematically equivalent. Hence the polymer option in Eclipse-100 is applied to model low salinity water injection with induced fines migration. The modeling results showed that injection of 0.004 PVI of low salinity water above WOC resulted in significant reduction in produced water and improvement of oil recovery with no adverse effect on the oil production.
Hydraulic Fracturing in the Dutch Posedonia Shale
Authors: Janszen M. , Bakker T. , Zitha P. L.
Published: May 2015

This paper reports a critical review of the operational principles and the most important completions techniques used in hydraulic fracturing in the U.S.A. and investigate whether they are applicable to the Posedonia geological and surface environment conditions in Europe. It is found that both cemented liner and open-hole with external packers completions wells have been used in shale gas developments. Plug and Perf and continuous pumping multi-stage hydraulic fracturing methods were respectively used. Low viscosity fracturing fluids are preferred to increase fracture complexity in brittle shale. Large stimulated reservoir volume by increase fracture density effective fracture half-lengths and use of proppant techniques to increase fracture conductivity. It is found that the Posedonia shale is comparable to several U.S.A. shale pays in terms of geological and petrophysical attributes (porosity, permeability, thickness, gas, oil and water content water). Therefore, we expect the multi-stage fracturing techniques developed in the U.S.A. to be largely applicable for the Posedonia shale. However, larger softness and greater depths of the Posedonia shale make more viscous fracturing fluids and fewer but much longer horizontal wells inevitable. Provided such longer horizontal wells are used, production rates similar to those reached in U.S.A. shale gas wells could be achievable.
A New Technical Standard Procedure to Measure Stimulation and Gravel-pack Fluid Leak-off under Dynamic Conditions
Authors: Asadi Mahmoud , Ainley Brian , Archacki David , Aubry Eric , Brannon Harold , Ghalambor Ali , Parker Mark , Watson Russell
Published: May 2015

Historically, leak-off analyses of stimulation fluids have been performed using in-house laboratory procedures. The lack of industry standard procedures to perform leak-off and wall building coefficient analyses of stimulation fluids has introduced inconsistency in both results and reporting for many years. A technical standard adopted in 2006 by both API and ISO for static conditions has provided the oil and gas industry with the first standardized procedure to measure and report leak-off1. However, the more complex testing under dynamic conditions was not addressed. As a result, a group of industry experts have compiled their years of experiences in developing a new technical standard to measure the leak-off characteristics of stimulation and gravel-pack fluids under dynamic flow conditions.

Stimulation and gravel-pack fluids are defined, for the purpose of this technical standard, as fluids used to enhance production from oil and gas wells by fracturing and fluids used to place filtration media to control formation sand production from oil and gas wells. Leak-off is the amount of fluid lost to porous media during these operations. The leak-off procedure was developed through the collaboration of several industry companies by evaluating numerous in-house laboratory techniques and conducting round robin testing to ensure that any modifications to these procedures were reliable and repeatable. The new standard provides a step-by-step procedure that includes fluid preparation, experimental equipment design, testing procedure and data analyses for fluids exhibiting viscosity controlled leak-off or wall building characteristics. Example calculations are reviewed within this paper.
Comparison of Streamline Reservoir Simulation of Brine Flow, Mixing and Barium Sulphate Induced Formation Damage with Observed Produced Water Chemical Data to Aid Scale Management
Authors: Hu Yisheng , Mackay Eric , Vazquez Oscar , Ishkov Oleg
Published: May 2015

In waterflooded reservoirs under active scale management produced water samples are routinely collected and analysed, yielding information on the evolving variations in chemical composition. These produced water chemical compositional data contain clues as to the fluid/fluid and fluid/rock interactions occurring in the subsurface, and are used to inform scale management programmes designed to minimise damage and enable improved recovery.

In this interdisciplinary paper, the analyses of produced water compositional data from the Miller Field are presented and a 1D reactive transport model is developed to study possible geochemical reactions taking place within the reservoir through matching model results with observed produced water data. However, in the 1D reactive transport model, only one flow path was simulated; this does not fully represent the fluid flow and mixing behaviour in the reservoir.

Therefore, this paper also presents a fully 3D reservoir simulation study for the Miller Field to evaluate brine flow and mixing processes occurring in the reservoir, using an available history matched streamline reservoir simulation model integrated with produced water chemical data. Conservative natural tracers were added into the modelled injection water, and then the displacement of injection water and the behaviours of the produced water in two given production wells were further studied. In addition, the connectivity between producers and injectors was investigated based on the comparison of production behaviour calculated by the reservoir model with produced water chemical data, and an assessment of the properties of the intervening faults was also performed. Finally, a model of BaSO4 scale precipitation was included in the model, and the simulation results with and without barite precipitation were compared with produced water chemical data (observed barium and sulphate concentrations in the produced brine). In general, the modelled and observed data were found to be in good agreement, but any discrepancies were in fact found to be very informative also. The model assumes scale deposition is possible everywhere in the formation, whereas in reality the near production well zones were generally protected by scale inhibitor squeeze treatments, and thus the discrepancies between modelled and observed data could be used to diagnose the effectiveness of the chemical treatments to prevent formation damage around the production wells.
In-Situ Microemulsions Enhance Removal of Non-Aqueous Drilling Fluid in Gulf of Guinea Wells
Authors: Pietrangeli Gianna , Quintero Lirio , Gonzalez Yohnny
Published: May 2015

Efficient removal of the drilling fluid from tubulars, screens, and near-wellbore mineral surfaces is essential to the successful completion of wells. Cleaning and removal of the non-aqueous drilling fluid (NADF) from all of the well surfaces is not an easy task. Microemulsion fluids provide a highly-successful solution to this problem.

Carefully designed and customized microemulsion fluids have been used to remediate and increase well productivity and injectivity in wells located in the Gulf of Guinea. Due to their uniform wellbore cleanup, optimum results were achieved in open-hole horizontal and highly-deviated wells. The robust microemulsion fluid systems are capable of accommodating changes in temperature, density, and salinity. They restore the water-wettability of the rock and increase injectivity or productivity of the wells.

Some water injectors and oil producers from the Gulf of Guinea exhibited low injection or production rate. The purpose of pumping the treatment downhole was to improve injectivity by removing skin damage and screen blockage by using in-situ generated microemulsions, thus allowing efficient oil production from the formation or water injection at sustainable high-injection rates into the formation.

Field data shows that injectivity and productivity increased after treatment. In some cases, the downhole pressure decreased for the injectors. Cleanup and removal of the NADF from the Gulf of Guinea wells was beyond the capabilities of conventional treatments. Laboratory tests confirmed that the in-situ microemulsion treatment removes the damage and helps to achieve the desired and predicted injection and production rates. This paper presents field data, before and after the successful microemulsion fluid treatment, and describes various laboratory tests performed prior to the Gulf of Guinea field applications.
Next Generation Acid System – First Field Trial of a New Biodegradable Fluid in a Sandstone/Granite Formation
Authors: Lummer Nils Recalde , Rauf Omair , Gerdes Steffan
Published: May 2015

This paper introduces a new retarded stimulation system which is based upon an environmentally friendly, biodegradable acid and highlights its first field trial in a sandstone/granite formation. Here, demanding borehole conditions (165°C, anhydrite and carbonate scales, highly fractured sandstone and granite) as well as strict regulations regarding environmental impact of stimulation fluids set forth by mining and water authorities were encountered.

Extensive laboratory tests regarding reactivity, acid corrosion tendency, and fluid compatibility were conducted preparing the first application in a geothermal well. In contrast to HCl-based fluids, this state of the art acid system has a low corrosion tendency and an excellent compatibility profile, even at high temperature.

The superior chemical properties of this stimulation system combined with an outstanding performance of inflatable packers in the openhole section lead to a greatly enhanced injectivity of the geothermal well. Laboratory and field results impressively proved that this new biodegradable acid system is an excellent alternative to commonly used HCl-based fluids.
Nanosilica-based Conformance Gels
Authors: Boul Peter J. , Ye Allan , Pang Xueyu , Goel Vivek , Eoff Larry , Reddy B R
Published: May 2015

Conformance gels based on nanosilicas are used as environmentally acceptable materials for plugging and sealing water- or gas-producing zones and controlling water production. Because of the lower pH(compared to sodium silicate solutions) of these solutions, they are environmentally acceptable in the North Sea area. The gelling agents required to activate the materials to produce gels are typically common salts, such as sodium chloride and potassium chloride.

The reduced environmental impact of nanosilica has led to its commercial success in the North Sea. At temperatures greater than 80°F, the gel time of nanosilica can be controlled to desirable values by adjusting concentrations of the gelation agents. The nanosilicas that are currently used in the oilfield, however, are not suitable for low-temperature applications (e.g., below 80°F) because of extremely long gel times.

This paper describes a new nanosilica system that demonstrates non-spherical-shaped nanosilica particle assemblies, such as rod-like and string-of-pearl geometries that display superior gelation activity in the presence of salts, exemplified by sodium chloride, compared with their spherical counterparts. These materials can gel in a reasonable time frame in the presence of an activator at temperatures as low as 50°F.

A trend of increasing reactivity in nanosilicas based on their geometries is presented in this paper. In particular, nanosilicas with a high aspect ratio render stable gels in a shorter period of time than their spherical counterparts. It is proposed that the aspect ratio could enable formation of a networked superstructure of silica at lower concentrations than required for a networked structure of nanosilica spheres of similar diameter.
Prevention of Calcium Carbonate Precipitation during Water Injection into High-Pressure High-Temperature Wells
Authors: Khormali Azizollah , Petrakov Dmitry G. , Lamidi Abdul-Latif Benson , Rastegar Reza
Published: May 2015

Complex technical problems, including salt precipitation, can occur during the entire period of the operation and production of the oil from reservoirs in high-pressure/high-temperature (HPHT) condition. Inorganic salts deposition occurs during the mixtures of different waters, which are incompatible with each other. These combinations of waters mostly can be done during waterflooding into the reservoirs to pressure maintenance. For the effective development of oil reservoirs, which are associated with the deposition of inorganic salts in HPHT, the selection of inhibitors is required to prevent scaling accounts for the characteristics of the reservoirs. Effectiveness of the scale inhibitors concentration for specific well conditions is verified by laboratory tests, considering total dissolved salts and hydrochemical conditions of the formation. The amount of calcium carbonate (CaCO3)) precipitation in synthetic formation water was investigated in mixing with the injected water in the range of 100-200°C for temperature and 40-70 MPa for pressure. Also, calcium carbonate precipitation was considered in a well at 200°C and 70 MPa in a simulation model with an electrical submersible pump (ESP). The results of the experiments showed that the possibility of calcium carbonate deposition was increased by growing the amount of the formation water and temperature. Increasing the pressure had reverse effect on scale formation. In this investigation, a new inhibitory chemical composition was developed. This scale inhibitor is based on the aqueous solutions of different acids and isopropyl alcohol. The inhibitor was considered for compatibility with formation water and core samples; and it was compatible with them at reservoir condition. The new scale inhibitor had a greater inhibition efficiency and low permeability damage in comparison with the tested inhibitors. The used materials were effective for scale prevention at high-level. The synergistic inhibitory effect has been considered for mixtures of inhibitors.
A Model for Real Gas Transfer in Nanopores of Shale Gas Reservoirs
Authors: Wu Keliu , Chen Zhangxin , Wang Heng , Yang Sheng , Li Xiangfang , Shi Juntai
Published: May 2015

The gas transport in nanopores of shale gas reservoirs is significantly different from that in conventional gas reservoirs. A model for ideal gas in nanopores is derived based on a weighted summation of slip flow and Knudsen diffusion, where ratios of intermolecular collisions and molecular and nanopores wall collisions to total collisions are the weighted factors of slip flow and Knudsen diffusion, respectively. This model is extended to the application of real gas transport in nanopores by taking into account the effects of intermolecular force and gas molecule volume on mass transport under the condition of high pressure. The model is validated by published molecular simulation data. The results show that the model is more reasonable to describe all of the gas transport mechanisms known, including continuous flow, slip flow and transition flow; the degree of real gas effects on gas transport is up to 23%, which is controlled by pressure, temperature, nanopores radius and gas type; and methane transport capacity is underestimated by 65.09% with helium and overestimated by 106.27% with nitrogen in simulation of methane transport in shale nanopores under the condition of laboratory experiments.