bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvise!™: Jazz Consultancy and the Aesthetics of Neoliberalism
Authors: Laver Mark
Published: March 2016

Group musical improvisation represents a profoundly collaborative creative process. The improvised framework demands that musicians collectively and spontaneously negotiate a set of dynamic musical and non-musical challenges. Similarly, in the post-fordist global marketplace, unexpected challenges have become a quotidian part of the business experience. Just as a group of musical improvisers must negotiate sudden musical changes, unanticipated changes in the marketplace demand a collaborative creative response.

Since the early 2000s a wide variety of corporations have begun looking to group musical improvisation as a model for corporate design. Corporations ranging from Starbucks to Procter & Gamble to Research In Motion have hired improvising musicians to run seminars and workshops in order to develop more improvisatory – and more profitable – business practices. Complicating this narrative, however, is the ethic that is commonly attached to improvised musical practice: as numerous scholars have suggested, improvised musics frequently emerge from marginalized communities around the world, and often represent kinds of musicking that purposefully challenge the logics of the free market economy, especially in its present neoliberal guise.

In this article, I suggest that this species of arts-based consultancy - together with a huge and ever-expanding body of writing on "creativity" - operates to provide an aesthetic aspect to "creative" and "knowledge-based" labour in the postindustrial North American "knowledge economy," and by extension, to neoliberalism itself. I argue that this aestheticization of neoliberal economics threatens to occlude the profoundly socially destructive impact of the laissez-faire neoliberal regulatory regime that has taken hold of economic and social policy on an increasingly global scale over the last three decades. Finally, however, I explore how the lessons of improvisation studies might intervene in the corporate appropriation of improvisation.
Reading Ascension: Intertextuality, Improvisation, and Meaning in Performance
Authors: Strachan Jeremy
Published: March 2016

Feedback analysis has been a useful tool for ethnographers to get deeper into the contours of how expressive culture is meaningful for those involved in its production. This paper looks at how feedback analysis might work in the case of improvisation, where the cultural text generated is born of contingency, spontaneity, and ephemerality. I interview a group of musicians who participated in a performance of John Coltrane’s landmark work Ascension, a piece that has come to occupy a unique position in the canon of experimental jazz. In examining the performance (and its recording) as text, our interviews yield a plethora of readings that align with structural and poststructural modes of interpretation. In this case, feedback interviews function to elaborate understandings of the performed and interpreted text, but also illuminate the "extra-textual" dimensions of expressive culture that often remain deemphasized and hidden.
Bone Mineral Density in Elite DanceSport Athletes
Authors: Kruusamäe Helena , Maasalu Katre , Jurimäe Jaak
Published: March 2016

This study compared bone mineral density (BMD) variables of female and male elite dancesport athletes with untrained control subjects of the same gender. Sixty-six elite dancesport athletes (M 33, F 33) and 64 untrained controls (M 34, F 31) participated in this study. Elite dancesport
athletes were dancing couples competing at the international level. Whole-body bone mineral content and whole-body, forearm, lumbar-spine, and femoral-neck BMD, as well as whole-body fat mass and fat free mass, were measured by dual-energy X-ray absorptiometry. There were no differences (p>0.05)
in height and body mass between dancers and controls of the same gender, but percent body fat was lower (p<0.05) in dancers of both genders than in untrained controls. Elite dancesport athletes had significantly higher femoral-neck BMD, and male dancers also higher whole-body BMD values
when compared with controls of the same gender. All other measured bone mineral values did not differ between the groups of the same gender. In addition, training experience was positively correlated with whole-body BMD (r=0.27; p<0.05) in dancesport athletes. Based on this study, it can
be concluded that elite dancesport athletes have higher BMD values at the weight-bearing site (femoral-neck BMD), while other measured areas and whole-body bone mineral values do not differ from the corresponding values of healthy sedentary controls of the same gender. According to our results,
low BMD is not an issue for elite female dancesport athletes, despite their lower percent body fat values.
Hearing Health in College Instrumental Musicians and Prevention of Hearing Loss
Authors: Olson Anna D , Gooding Lori F , Shikoh Fara , Graf Julie
Published: March 2016

OBJECTIVE: College musicians exhibit greater declines in hearing than the general population and are at particular risk because they rehearse and perform daily in loud environments. Also, they engage in use of personal listening devices which increases the amount of “exposure”
time. Despite increased risk, many do not use hearing protection devices (HPD). The purpose of this study was to (1) to identify the present level of education about hearing health, (2) identify the perceived advantages and disadvantages of using HPD, and (3) evaluate results among different
musical instrument groups. METHODS: A mixed-methods group design was used including both quantitative and qualitative instruments. SPSS was used to generate descriptive statistics, and non-parametric statistical analysis was performed on quantitative data. NVivo software was used to evaluate
qualitative responses. RESULTS: Of the 90 college instrumental music students who participated, 12% reported a history of hearing loss, and over one-third reported tinnitus. Seventy-seven percent of participants had never received any training about hearing health and only a small percentage
of students used HPD. The most cited reason for lack of protection use was its negative impact on sound quality. However, group differences were noted between brass, woodwind, and percussion musicians in terms of HPD uptake. CONCLUSION: Improving the type of information disseminated to college
musicians may reduce the risk of ear-related deficits. Noise dosage information, HPD information, and prevention education grounded in theories like the Health Belief Model may increase awareness and promote greater use of HPDs in this population.
Toward an Alternative Bio-Based SP Flooding Technology: II. Biopolymer Screening and Evaluation
Authors: AlZahid Yara A. , AlBoqmi Abdullah M. , AlSofi Abdulkareem M.
Published: March 2016

Surfactant-polymer (SP) flooding is one of the most promising methods in enhanced oil recovery, especially where an existing waterflooding infrastructure is in place. Surfactants lower the interfacial tension between the injection brine and crude oil, which improves microscopic displacement efficiency by mobilizing trapped oil. In contrast, polymers increase the viscosity of injected water, which improves macroscopic sweep efficiency by stabilizing the displacing front and counteracting heterogeneity effects.

This work is part of a broader research theme in which our group is evaluating the potential of biochemicals for chemical enhanced oil recovery (CEOR). Previously, the potential of a non-ionic alkyl polglycoside biosurfactant was demonstrated for a CEOR application in a carbonate reservoir characterized by high temperature and high salinity. In this work, we evaluate the potential of several biopolymers obtained from various manufacturers. We evaluate biopolymer compatibility, viscosibility, stability, injectivity, and adsorption. We benchmark its performance against a synthetic polymer that had previously proven potent. Compatibility with the field brines (injected and connate) were investigated by observation of solution appearances. Viscosibility was investigated by measuring viscosity of solutions at various concentrations, temperatures, and shear rates. Viscosities after prolonged heating were used to investigate the stability of the biopolymers. Injectivity was studied by measuring filtration ratios. Finally, static adsorption tests using crushed core plugs were conducted, and changes in surfactant concentration, i.e., adsorption, was inferred using a total organic content analyzer.

Among the tested biopolymers, one biopolymer showed potential in terms of compatibility, stability, viscosibility, injectivity, and adsorption. Compared to the synthetic polymer, the biopolymer exhibited superb viscosibility. Concentrations around 750 ppm were sufficient to achieve the targeted viscosity at reservoir conditions. This translates to lower chemical usage and possibly improved economics. A coreflood, where the biopolymer was injected in a tertiary mode, demonstrated an additional production of around 5.2% original oil in the core (OOIC). A subsequent biopolymer/biosurfactant flood achieved an ultimate additional production of 15.5% OOIC. This performance is comparable but slightly lower (2.5% OOIC lower) than recoveries obtained with the benchmark polymer when applied as part of an SP slug. The results discussed in this paper constitute a major advancement toward developing an alternative bio-based SP flooding technology.
Studies on Surfactant-Polymer Combination Flooding Formulations for a High Salinity Reservoir
Authors: Zhu Youyi , Lei Ming
Published: March 2016

Alkaline-surfactant-polymer (ASP) combination flooding field tests showed that it could significantly enhance oil recovery for high water cut mature oilfields in China. The main problem in ASP flooding was the difficulties in lifting system and produced liquid treatment process due to scaling, erosion and strong emulsification caused by alkali. To avoid the side effects caused by alkali, the tendency of chemical combination flooding changes from ASP flooding to low damage combination flooding formulations such as alkali-free surfactant-polymer (SP) combination flooding. The main challenge in SP flooding is to develop surfactants with highly effective interfacial tension (IFT) reducing ability, low adsorption and good oil displacement ability especially at high salinity reservoir conditions. Yumen oilfield is a high salinity sandstone reservoir. It is a mature oilfield developed by water flooding over 60 years. A candidate EOR technique with SP chemical flooding has been proposed.

This article related the surfactant screening, IFT properties measuring, surfactant adsorption loss testing and oil displacement experiments of SP chemical flooding formulation for Yumen oilfield based on a new type surfactant alkyl polyoxypropylene ether sulfate (APES).

A series of APES surfactants were synthesized by carbon chains with different lengths and structures. The IFT measurements of both model oil/water and crude oil/formation water indicated that IFT could be significantly affected by the molecular structure of surfactants such as the length of carbon chain and propylene oxide (PO) units. The formulations of SP systems were optimized with crude oil/formation water. Ultralow IFT between crude oil and SP fluid could be obtained at the concentration range of surfactants from 0.1wt% to 0.3wt%. The dynamic adsorption experiments showed that adsorption loss of surfactant APES on the core was about 0.36 mg/g rock. Core flooding experiments of SP combination flooding showed that the incremental oil recovery for Yumen oilfield crude oil could reach to 17%-21% over water flooding.

The synthetic process of APES is simple and the surfactant is environmentally friendly. It has potential to be applied in SP chemical combination flooding to enhance oil recovery under high salinity reservoir conditions.
Studies on a Hybrid of Foam and ASP Flooding Further EOR for the Reservoir after Polymer Flooding
Authors: Zhu Youyi , Fan Jian , Hou Qingfeng
Published: March 2016

Most of the high permeability reservoirs in Daqing Oilfield have been conducted by water flooding and polymer flooding. The average recovery percentage of OOIP has reached to 52.6% after polymer flooding. Currently, the further development of such reservoir has become a big challenge due to both of serious heterogeneity of reservoir and highly dispersed remaining oil. The reservoir development has entered into quaternary recovery stage. Most of conventional enhanced oil recovery (EOR) techniques could not achieve the desired effects. A hybrid of foam and alkali-surfactant-polymer (ASP) flooding, as a candidate further EOR technique integrating both properties of mobility control and oil displacement has been proposed for Daqing reservoir after polymer flooding.

In this study, systematic laboratory experiments on foam formulation, ASP formulation and hybrid of foam/ASP flooding for Daqing reservoirs have been performed after polymer flooding. Several key parameters of the hybrid systems of foam/ASP flooding that influences on oil recovery efficiency were investigated and optimized. Further EOR effect of the hybrid flooding on core flood was evaluated.

The main factors that influences on oil recovery efficiency by a hybrid of foam/ASP flooding were described as below. Firstly, the properties of foam formulation and slug sizes were the key factors to ensure high performance of recovery. The foam formulation was optimized with good performances of foamability and stability. Secondly, the properties of ASP formulations and slug sizes also play important roles in EOR efficiency. The ASP formulations were optimized with ultralow interfacial tension. Concentration of chemicals and slug sizes were the main factors for oil displacement efficiency. Thirdly, a hybrid of foam and ASP flooding was optimized at the reservoirs condition. EOR effect of the hybrid flooding was studied upon three-layer positive rhythm sandpack cores flooding tests. The results indicated that hybrid flooding contributed 17%-20% of OOIP recovery as the recovery background was already 53% after polymer flooding.

The foam flooding could block preferential flow path of high permeability layer in heterogeneous reservoirs. On the other hand, ASP flooding also had higher oil displacement efficiency for the relatively low permeability layer. The hybrid of foam/ASP flooding might become a promise alternative further EOR method for Daqing reservoirs after polymer flooding.
Water Conformance Treatment using SMG Microgels: A Successful Field Case
Authors: Dupuis G. , Lesuffleur T. , Desbois M. , Bouillot J. , Zaitoun A.
Published: March 2016

SMG Microgels are pre-gelled polymers having a narrow size distribution and behaving like large polymer molecules whose stability is strongly enhanced by internal crosslinks. The largest species have a size of around 2 μm, which makes them suitable for Water Shutoff and Conformance Control applications in matrix reservoirs. SMG Microgels have been firstly used as water shutoff agents in gas storage wells and showed high efficiency to reduce water production while enhancing gas production. This paper reports a Conformance project which has been recently deployed in a heterogeneous sandstone reservoir. The pilot pattern consisted of one central injector, surrounded by 7 offset producers, with a spacing between 150 and 450 m. Reservoir permeability ranges between 10 and 1,000 mD with an average of 125 mD. Reservoir temperature is 48°C and salinity is 8,000 ppm TDS.

Soft SMG with size around 2 μm was chosen regarding reservoir conditions. Microgel size prevented invasion of lowest permeability zones and created flow resistance in highest permeability zones by adsorption on the rock. Microgel slug corresponded to 0.1 Pore Volume and was 10,000 m3. Microgel injection proceeded over a period of 3 months. WHP remained below max pressure authorized of 1,500 psi.

Closest producers responded within 3 months after microgel injection, with noticeable increase in oil rate along with a reduction of a few points of water cut. After one year 6 offset producers upon 7 were responding to the treatment. Three producers showed strong increase and sustained oil production, three had low response and one well lost both water and oil, showing diversion to the other wells. The trend remains steadily established in the pattern. After one year, 10,000 bbl of additional oil has been produced, along with a reduction of water production of 125,000 bbl.
Controlling Interactions of Colloidal Particles and Porous Media During Low Salinity Water Flooding and Alkaline Flooding By MgO Nanoparticles
Authors: Assef Y. , Pourafshary P. , Hejazi H.
Published: March 2016

Enhanced oil recovery has become a hot topic nowadays. Low-salinity water (LSW) and alkaline flooding are known as two efficient improved oil-recovery techniques to unlock residual oil. An enhanced oil recovery (EOR) project's success will be endangered when the production target is not achieved due to migration of fines, which affects reservoir permeability near the wellbore and leads to declining productivity. In this work, our experimental study aims to use nanoparticles (NPs) for the treatment of colloidal particles migration to improve the performance of the mentioned EOR methods.

In LSW and alkaline flooding methods, one critical step is the precise selection of fluids, which increases the effectiveness on these techniques. Therefore, one should choose the optimum salinity rather than the lower one to enhance the efficiency of a typical LSW project and also the optimum pH for the injected slugs rather than the higher one to improve the efficiency of an alkaline flooding project. These limitations make the design of such flooding projects very difficult and challenging. The purpose of this study is to clarify how solution conditions (pH and ionic strength) act upon surface potentials and charge distributions close to solid surfaces. Also the effects of MgO NPs on the point of zero charge (PZC) and critical salt concentration (CSC) are inspected. Zeta potential and turbidity analyses have been utilized as useful tools to examine the effect of NPs on the interactions of colloidal particles with the medium surface.

Our results illustrate that the magnitude of the repulsion forces compared to the attraction between fines particles and pore wall surfaces was considerably diminished when the surface of the glass beads was soaked with MgO NPs. The presence of MgO NPs on the bead surface significantly modifies the PZC, increasing it from 3 to around 9, which in turn justifies the retention of particles in a wide range of alkaline conditions. It was found that the MgO NP-treated medium tends to retain around 97% of the in situ fine particles under very alkaline conditions. A decrease in CSC for all divalent and monovalent salt solutions was also quantitative evidence of a striking improvement effect of these NPs. Therefore, pre-flushing of the medium with a slug of MgO nanofluid prior to alkaline flooding or LSW injection into the reservoir can serve as a promising remedy to counteract the subsequently induced migration of colloidal particles.

This technique is of great interest for application in the field, where improved oil recovery is desired; however, fines migration and subsequent formation damage should be avoided. This method minimizes the creation of damage, prevents severe plugging in the near-wellbore area, and improves communication between the wellbore and the virgin formation.
An Operational Workflow for Polymer EOR Field Trials
Authors: Geremia Giuliano , Bennetzen Martin Vad
Published: March 2016

Polymer flooding is the most commonly tested chemical EOR strategy worldwide. The method aims at improving the macroscopic sweep efficiency by reducing the mobility ratio, the viscous fingering and the permeability in high-perm streaks. Although a number of on-shore field trials have been performed, polymer flooding is still rarely used for offshore fields. The logistics and facility requirements make the operational design and execution more challenging in an offshore environment. The decision of conducting an offshore polymer EOR field trial must be supported by a strong technical evaluation (laboratory and simulation studies) and thorough operational field trial design that aims at targeting the different challenges to reduce risk and uncertainty and increase the likelihood of success. We present the logistical, technical and operational aspects of the design of an offshore polymer flood.

In this paper we present a procedure to minimize risk and reduce uncertainty by initial laboratory tests and continuous monitoring of key parameters when conducting the field trial. We address the logistical considerations and facility requirements related to polymer solution storage, polymer integrity, chemical additives, mixing, handling and real-time quality control. All necessary and critical parameters to be monitored are described herein. We describe the possible drag reduction induced by the polymer in the tubing, the near-wellbore shear effect on the injectivity and the pressure gauge setup essential to make a quantitative trial evaluation. We also discuss the potential impact of the polymer on the produced oil-water mixture and a way to mitigate polymer-induced emulsification via demulsifiers. Various operational conditional ‘what-if' scenarios are considered to provide a tailor made solution for each of them. Finally, we show how inter-well tracer tests can be used to evaluate polymer EOR trials wrt. macroscopic sweep improvement.

Currently, very few papers describe both operational and technical aspects, and very few papers suggest practical procedures for offshore polymer floods. With the increased focus on offshore EOR implementation due to production decline and reservoir maturation, this paper aims at providing a practical guideline and a best practice operational workflow for the design, execution and evaluation of offshore polymer EOR field tests.
A Numerical Method for 3-Dimensional Fluid Front Investigation for Long Horizontal Wells Using Pressure Transient Analysis
Authors: Gilani Syed Furqan , Tarsauliya Gunja , Bennetzen Martin V. , Evans C.
Published: March 2016

This paper presents a 3-dimensional numerical simulation approach and derivation of a simple analytical expression to track the fluid fronts using pressure transient analysis in long horizontal wells. In general, fluid front tracking studies are rarely used for horizontal wells. In the past, analytical models, such as radial composite model, have been used to estimate fluid front distance, which do not account for changed mobility due to different fluid saturations and relative permeabilities. The main assumption for an analytical model is to consider constant mobility for flooded and un-flooded reservoir regions. Hence, an appropriate methodology for fluid front estimation would be numerical analysis of pressure transients.

The study has been conducted for a homogeneous and low permeability artificial reservoir with long horizontal wells. The results show that changes in fluid properties at flood front cause a slope change in pressure response. An equation has been derived to calculate the distance to the flood front (diagnosed as a slope change), which follows the form of the standard equation for radius of investigation. The equation includes a constant ‘A' which is possibly dependent on permeability of the reservoir and relative permeabilities of the fluids. Various sensitivities have been performed to understand the dependency of the constant ‘A' on reservoir and fluid properties. In addition, it is shown that the constant ‘A' does not vary significantly with porosity, viscosity, reservoir thickness, well length and total compressibility of the system.

With a properly designed program for acquiring pressure transient data combined with the presented methodology, distance to fluid fronts can be estimated with reasonable accuracy.
Successful Field Test of a New Polymer Flooding Technology for Improving Heavy Oil Reservoir Recovery -- Case Study of Strongly Heterogeneous and Multi-Layer Conglomerate Heavy Oil Reservoir XJ6
Authors: Wu Xingcai , Zhang Song , Xiong Chunming , Liu Shunsheng , Cai Cheng , Zhao Meigang , Yu Zhentao , Li Bin , Xu Hanbing , Wu Yongfeng , Yang Ning , Ye Yinzhu , Tian Xiaoyan , Chen Jingjing
Published: March 2016

XJ6 is a conglomerate reservoir, with oil viscosity 80mPa.s. It is similar to carbonate reservoir that the formation sedimentation does not show obvious rhythm. The pore structure and size varies greatly, with dual and complex porosity and permeability distribution, causing seriously uneven sweeping. Traditional polymer flooding technology is not suitable. A pilot test, conducted in 2013, used a new particle-type polymer, combining several small polymer gel slugs, obtaining obvious oil rate increase and water cut decrease.

Cores were sampled from 8 sealing core drilling wells. The casting core film images were analyzed, and the microscopic structure of formation pores was studied. The pore size and distribution were quantitatively characterized by mercury injection testing data, and also predicted by geology modeling. The macroscopic water flowing channel distribution and volume were quantified through numerical simulation and tracer test, based on which, the combined slug parameters of polymer flooding were designed.

There are 5 injectors and 11 producers in the pilot. Related testing results show that the water flowing velocity between injector and producer varies with big difference, 17 times, and the highest velocity is 27.7 m/d. It is developed with wide range of pore radius, 1.72-354.6μm. To control water cut rising, injection and production rates were kept at low value. The remaining oil distributed in complex porosity and permeability zones was hard to be initiated. The injection plan was alternating injecting the slugs, consisting of big slug of the new particle-type polymer dispersion with particle size in the grade of micrometer, and small slug of crosslinked polymer. The injection liquid amount is 0.2PV. One month after the test started, the water cut of the pilot began to decrease fast and the daily oil rate began to increase fast. The daily oil rate was increase to 62.2 t/d from 16.1 t/d, and the water cut was decreased to 35.8% from 82.0%. The center well got better effect. The average injection pressure of the pilot was increased by 2MPa. The daily water injection rate and daily liquid production rate were increased by 20% gradually.

By the pilot test, the new oil displacing mechanism and slug design method were explored, achieving a success. It was shown that, for conglomerate reservoir with complex formation pore structure and large pore size difference, with the previous slug of highly viscous polymer gel to inhibit the large channels, taking the new submillimeter/micrometer grade particle-type polymer slug can favor displacing the remaining oil.
Can Associative Polymers Reduce the Residual Oil Saturation?
Authors: Reichenbach-Klinke Roland , Stavland Arne , Strand Daniel , Langlotz Björn , Brodt Gregor
Published: March 2016

The oil recovery potential of acrylamide-based, associative thickening polymers has recently been evaluated in a coreflood study of our department. Associative polymers are anionic, water-soluble copolymers modified with varying degress of pendant hydrophobic groups. By intermolecular interactions of these hydrophobic moieties a fully reversible network of polymer coils can be formed.

The oil recovery efficiency of a series of copolymers based on acrylamide, 2-acrylamidopropane sulfonic acid (ATBS) in combination with a hydrophobic comonomer has been determined in linear coreflood experiments at a temperature of 60°C. Synthetic sea water was used as brine and Bentheimer sandstone as core material. The evaluated polymers differed in molecular weight and associative groups' content.

While anionic polyacrylamide (APAM) shows very similar resistance factors (RF) in coreflood experiments with and without oil, a significantly reduced RF in the presence of oil has been found for the associative polymers. The magnitude of this decrease in resistance factor was dependent on the specific type of associative polymer.

The effect can be ascribed to the weakend intermolecular interaction of the hydrophobic groups in the associative polymers in the presence of oil. Even though the RF value is reduced in the presence of oil, it still remains higher than that of regular APAM.

At low flow rates representing reservoir conditions a high resistance factor was observed and oil production was improved. This observation can be explained by an increase of the capillary number caused by the high RF of the polymer drive. A good correlation between oil production and capillary number was established.

Permeability reduction effects explained the high mobility reduction observed with the associative polymers, as the bulk viscosity data did not correlate with the in-situ flow properties of the polymers in porous media.
Evaluation of Mixing in Low Salinity Waterflooding
Authors: Attar Ahmed , Muggeridge A. H.
Published: March 2016

The impact of heterogeneity induced mixing between the injected low salinity water and the high salinity connate water is investigated in secondary low salinity waterflooding (LSW). Although LSW has proved to be a promising EOR process in laboratory experiments and field trials, its efficiency can be reduced due to mixing with in situ higher salinity connate water. This mixing is caused by molecular diffusion and dispersion and it has been suggested that it may be exacerbated by heterogeneity.

We have investigated the impact of 1) conformance caused by layering in the sandstone and 2) mixing caused by water-saturated shale layers adjacent to the reservoir sand on recovery. The study used a commercial reservoir simulator in which low salinity flooding is modelled by varying relative permeability as a function of salinity. All simulations used very fine grids so that physical (rather than numerical) diffusion and dispersion dominated the displacement. In single phase flow, it was found that physical dispersion can only be modelled for when the grid Peclet number is less than 60, for higher values numerical dispersion dominates over physical values. This threshold Peclet number varies with the number of grid blocks, e.g. the optimum number of grid blocks was found to be 10 for (Pe <12) compared with 1000 grid blocks (Pe = 60).

The transverse dispersion number (NTD) originally proposed by Lake and Hirasaki (1981) is shown to be a very robust way to measure the impact of mixing on the performance of LSW. Generally, for any (NTD > 1), diffusion dominates the flow and thus the efficiency of LSW is reduced. In layered high net to gross reservoirs mixing can actually improve recovery from low salinity water flooding and we find that the impact of molecular diffusion increases as the thickness of the higher permeability layer decreases. In lower net-to-gross reservoirs containing thin, shaly zones filled with higher salinity connate water molecular diffusion reduces the effectiveness of LS. This performance reduction is more noticeable as the thickness of the sand layers between the shales decreases.
CT-Scan Monitoring of Combined Chemical EOR Processes in Fractured Carbonate Cores
Authors: Rosenberg E. , Robin M. , Bourbiaux B. , Chabert M. , Chevallier E. , Gautier S.
Published: March 2016

Almost 60% of global oil reserves are contained in carbonate reservoirs. A large number of those are naturally fractured and oil- or mixed-wet. Waterflooding efficiency is often very low for such reservoirs because of both high fracture-to-matrix permeability contrast and unfavorable wettability. The recovery of the oil trapped in the matrix is then very challenging. To enhance this recovery, several recovery mechanisms can be assessed: –capillary imbibition by using wettability modifiers,–viscous drive by imposing a pressure gradient in the fracture network,–water-oil gravity drainage by using low IFT surfactants formulation.

This paper presents an experimental approach that evaluates different chemical EOR alternatives using one or several of the three previous recovery mechanisms. The experiments consist in injecting an aqueous chemical solution or a foam containing chemical additives into an artificially fractured carbonate core. The imbibition is monitored with a recent CT-scanner allowing the local quantitative monitoring of three phases, including accurate quantification of matrix oil recovery. This paper is mainly focused on the impacts of foaming agents and of wettability modifiers, implemented separately or jointly. The experiments have also been conducted on several cores of different permeability, resulting in various permeability contrasts between matrix and fracture.

A major result concerns the kinetics of oil recovery by chemical additives, that is greatly increased when a viscous drive is applied across the matrix medium via the circulation of foam in the fracture. Experiments in fractured cores of different permeabilities indicate that foam does not penetrate the matrix but drives the chemical aqueous phase into the matrix due to the generated pressure gradient. Detailed analysis of oil mobilization dynamics is provided. These foam flow experiments are compared with former chemical imbibition tests on non-fractured cores, for further insight of the role played by viscous forces. The comparison of tested recovery scenarios leads to conclusions regarding optimal chemical EOR strategies for naturally-fractured carbonate reservoirs with poor secondary recovery prognosis.
Solvent Enhanced Steam Drive: Results from the First Field Pilot in Canada
Authors: Castellanos-Diaz O. , Verlaan M. L. , Hedden R.
Published: March 2016

A solvent enhanced steam drive pilot has been executed in the Peace River area in Canada, where co-injection of steam and solvent was deployed in two inverted 5-spot 5-acre steam drive patterns. The results were compared to two adjacent patterns were only steam was injected. The pilot involved extensive metering and sampling surveillance during 1.5 years. After several months of starting the steam drive a large slug of solvent was injected, subsequently followed by steam drive. Several challenges emerged with respect to data accuracy and acquisition, inherent to the first deployment of this technology and of the pilot being a brown field project. To overcome these issues, a data uncertainty management plan was made aided by reservoir simulation. The pilot demonstrated significant bitumen uplift due to solvent injection and solvent recovery from the reservoir in line with expectations. A reservoir simulation model with sound physical principles was constructed confirming bitumen uplift estimates and solvent recovery trends seen in the field.
Low Tension Water Flood (LTWF) for Enhanced Oil Recovery in a Tight Carbonate Oilfield
Authors: Al-Rubkhi A. A. , Karimi M. , Hadji M. , Al-Maamari R. S. , Aoudia M.
Published: March 2016

The aim of this study is to develop and optimize a low tension water flood (LTWF) as an option for enhanced oil recovery in a tightcarbonate oilfield using a mixture of formation brines as injection water (total salinity: 165.9 g/L, Ca2+: 12.3 g/L, Mg2+: 2.0 g/L, and T = 70 °C.). In our approach, a combination of an anionic surfactant (alkyl ether sulfonate, C17EO7S(C17EO7) and a nonionic surfactant (alkyl ether, iC13EO10) were used to formulate clear and stable surfactant solutions at reservoir conditions.

Formulation and optimization of a LTWF at a very low total surfactant concentration (0.01 wt%) was achieved through surfactant/brine compatibility tests (target: clear and stable surfactant solution), surfactant solution/oil interfacial tensions (target: ~ 10-3 mNm-1), phase behavior (target: type II(-) oil-in-water microemulsion) and core flooding experiments.

Compatibility tests showed that the cloud point of the nonionic surfactant (0.01 wt%)is lower than the reservoir temperature (70 °C) whereas the clear point of the anionic surfactant is above the boiling point of water, suggesting that both surfactants cannot be used alone at reservoir conditions. On the other hand, clear and stable mixture of anionic/nonionic surfactants in the composition range fw = 0.1 – 0.8 (fw being the weight fraction of the nonionic surfactant) at 0.01 wt% total surfactant concentration were generated above 70 °C.

Clear, transparent and gel-free oil-in-water phase behavior with relatively high oil solubilization parameters (σo ~ 125) were observed for surfactant mixture (0.01 wt%, fw = 0.1-0.8). These phase behaviors tests were validated by interfacial tension (IFT) measurements. Ultralow IFT (~ 10-3mN/m) was achieved at fw = 0.2. This optimum system was selected for core flooding experiments. Injecting surfactant (0.5PV) slug into a fully water flooded carbonate core sample resulted in additional oil recovery of 10 % of OOIP. This is a very significant result owing to the low surfactant concentration used (0.01 wt%). In another experiment, injecting a surfactant slug (0.5 PV) before water injection resulted in a total recovery of 75% of OOIP. In addition, Amott-Harvey test showed that wettability indices of the core plug samples used in the experiments changed within a narrow range (– 0.231 to + 0.164); suggesting an alteration of wettability from slightly oil-wet to weakly water-wet state.
Monitoring IOR/EOR Onshore with Frequent Time-Lapse Seismic - Status and Survey Adaptations for the Middle East
Authors: Mateeva A. , Hornman K. , Grandi S. , Potters H. , Lopez J. , Follett J. La
Published: March 2016

IOR/EOR stimulation is a complex process that requires frequent areal monitoring to optimize recovery. On-demand seismic surveys are a suitable solution if cost, quality, environmental, and efficiency conditions are met. In this paper, we discuss the state of the art.

We show that frequent buried seismic has the necessary quality and was able to add value to steam injection operations at a heavy oil field in Canada. However, in its current form, buried seismic is too expensive and intrusive. That is why, for future deployments, we seek cost and footprint reductions through judicious reduction of survey frequency (from days to weeks or months apart) and novel survey designs such as a buried cross-spread with Distributed Acoustic Sensing (DAS) receivers and movable subsurface sources. We are in the process of maturing the buried cross-spread solution. Its application to some extreme settings found in the Middle East (deep reservoirs with weak seismic expression under thick and complex overburden) is expected to be challenging. A promising alternative already available is 4D VSP with DAS in multiple wells. This solution requires sufficient surface access, fiber optic cables in wells, and skillful seismic processing.
Improving Polymer Flooding Efficiency in Oman Oil Fields
Authors: Al-Hashmi A. R. , Divers T. , Al-Maamari R. S. , Favero C. , Thomas A.
Published: March 2016

Considering a depressed environment with low oil prices, optimizing the costs linked to polymer injection becomes important. In this paper, the efficiency of two polymers dedicated to Omani southern fields’ conditions have been evaluated: a standard copolymer currently injected in the Marmul field and another polymer optimized in terms of chemistry and polymerization process. The purpose is to ensure that changing the polymer will not impact the project efficiency. Consequently, the rheological properties, long term stability and injectivity have been compared for both polymers.

The standard polymer (P1) is a high molecular weight polymer widely used worldwide. The new polymer (P2) is a higher molecular product with better salinity and temperature resistances. In terms of rheological properties, P2 displays a higher viscosity in the field brine and also displays better viscoelastic properties with, in the end, a significant decrease of polymer dosage. Filterability of the polymer P2 is slightly poorer than for the P1, which is likely due to a higher molecular weight. P1 and P2 injectivity properties were assessed in two different cores: 100 mD Berea cores and 1500 mD Bentheimer cores. Both polymers propagate quite well in both core types showing no injectivity issues after injection of 4 to 5 pore volumes. In the Berea core, adsorption was approximately 42 µg/g for the P1 and 25 µg/g for the P2. Permeability reduction was nevertheless quite significant in such low permeability cores, and some face plugging was observed. In 1500 mD cores, adsorption valuewas determined around 12 µg/g and 10 µg/g for the P1 and the P2, respectively. Thermal stability for both polymers was performed in fully anaerobic or with specific amounts of O2 and H2S. The efficiency of two protective packages against H2S induced degradation was evaluated. The results after the incubation for 4 months highlight the need to avoid oxygen ingress in the system in presence of H2S. However, it is still possible to keep an acceptable level of viscosity by fine-tuning the protective additives.

This study demonstrates the viability of a cost-effective alternative to what is already used in the Marmul field. This new polymer can be an appropriate candidate to keep chemical EOR in Omani southern fields economically viable.
An Integrated Rejuvenation Project in the UK. From Gas Disposal Issue to WAG Opportunity
Authors: Manotti M. , Renna S. , Mattei M. , Foglio G. , Mariotti P.
Published: March 2016

Despite the increase of hydrocarbons exploitation from green fields in the last decades, the majority of the global production is still sustained by brown fields contribution. Rejuvenation of mature assets, as the one described in this work, plays a crucial role in current low oil price scenario, improving production with limited investments and risks.

Object of this work is an offshore oil field in the UK area in production since 1996. The field is developed by means of water injection for pressure maintenance and gas injection for disposal, with current water-cut higher than 90% and gas-breakthrough in wells close to the disposal area. After the acquisition of the operatorship in 2014, an asset rejuvenation project started, involving an integrated analysis of the field, based on the review of all available static and dynamic data. Combination of basic reservoir engineering tools and advanced modeling simulators was the key element of the performed analysis. This paper shows how an integrated workflow, combining skills from different professional families, allowed to find low cost opportunities with short time-to-market.

Production data analysis highlighted low efficiency of current water injection: majority of the injected volume is produced without displacing additional oil. Moreover, the new reservoir compositional model showed presence of by-passed oil in the crestal part of the field not displaced due to gravitational segregation effect.

Thanks to the better understanding of the field characteristics and fluids movement, different actions were planned in order to maximize oil recovery. In particular, a screening of possible IOR/EOR techniques showed immiscible WAG as the most promising one to recover un-swept attic oil. Several sensitivities were performed on water and gas injection rates, cycles duration and gas composition, in order to properly evaluate and maximize the expected additional recovery. Based on modeling results, two currently shut-in injectors were selected for a WAG pilot phase. The feasibility study highlighted that only minor plant changes were required, due to the availability of both water and gas injection facilities. This aspect drove the project economics into favorable evaluation. Moreover, moving gas injection from disposal to WAG mitigates well production problems in the disposing area, turning gas injection from an issue to opportunity extending field life.

This paper gives a detailed description of the rejuvenation project ongoing on an UK field which main outcome is the start-up of a WAG project. Advanced workflow, combining streamlines and conventional simulators, was used for waterflooding assessment and optimization. This integrated project was carried out with short time to market and minimal expenditure, showing how EOR processes can be an opportunity for field rejuvenation even in a low oil price environment.
Thermal EOR in Oman Heavy Oil Fractured Portfolio: Learning from Aquifer Communication and Offtake Management
Authors: Al-Aulaqi Talal , Soleimani Arash , Bellmann Lars , Attalla Hassan , Al-Azri Nasser
Published: March 2016

Thermal EOR is one of the success stories in the fractured carbonate portfolio in Sultanate of Oman. This paper summaries the challenges, learning and best practices in executing field developments plans in one of the complex reservoirs in Oman.

In Thermally Assisted Gas-Oil Gravity Drainage (TA-GOGD), steam injected into the top of the reservoir to achieve two important phenomena: first to apply a gas gradient across matrix blocks so that the oil in the matrix drains down by gravity and secondly to heat up carbonate matrix blocks to initiates various mechanisms including solution gas drive, thermal expansion and viscosity reduction of oil to drain oil faster.

The selected field candidate is a fractured carbonate that structurally segmented into two distinctive blocks: Crest block and Sub-crest block which they contain of 25% and 75% of STOIP respectively. It has been produced with cold production mode over 40 years of heavy oil (~ 700 cp) and ultimate recovery 2% of initial STOIIP. This field shared a common aquifer with other nearby developed fields. This paper intended to discuss a suggested development plan for a combination of challenging environment including: the heavy nature of the oil, the fractured nature of the rock, the offtake fluids requirements and the pressure management given aquifer communication with nearby fields.

The development strategy of oil rim is driven by steam injection rate optimization into Carbonate field. Two strategies are designed: (i) full steam injection in crest and sub-crest blocks and (ii) phase steam injection (starting by crest block and then followed by sub-crest). The following conclusions can be drawn: –Aquifer communication impact the gross evacuation decision and lowering pressure strategy.–The reservoir simulation model can be used to optimize the oil rim management in the fractures.