bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual Role of Citric Acid as a Binding Inhibitor of Anionic Surfactant with Bivalent Cations and Co-Surfactant on Bio-Surfactant EOR
Authors: Miyazaki Nao , Sugai Yuichi , Sasaki Kyuro , Okamoto Yoshifumi , Ouyang Chencan 
Published: November 2018

Abstract
Surfactin is an anionic surfactant generated by bacteria. Although it has high ability to decrease interfacial tension (IFT) between oil and water, it binds with bivalent cations and forms precipitation. Because the precipitation causes the significant reduction of reservoir permeability, surfactin cannot be applied to EOR in oil reservoir whose bivalent cations concentration is more than 100 ppm. This study investigated methods for applying surfactin to reservoir containing bivalent cations with high concentration.
Screening of an effective binding inhibitor was carried out by measuring turbidity of the solution containing 0.3 wt% of surfactin, 900 ppm of calcium ion, and inhibitor candidates such as alcohols, chelating agents, cationic surfactants, and ion capturing substances. Influence of the inhibitors on surfactin capacity for decreasing IFT was also evaluated by measuring IFT between the solution and oil. The best inhibitor was finally selected through the injectivity tests using Berea sandstone core which was saturated with calcium solution. EOR potential of the solution containing the inhibitor was evaluated by the core flooding experiments.
Citric acid and trisodium citrate inhibited binding of surfactin with calcium ion with lower concentration such as 0.6 wt%, they were selected as potential inhibitors and subjected to the IFT measurements. Both of them had strong potential as co-surfactants of the surfactin because IFT was greatly decreased to less than 0.1 mN/m which was less than a tenth as compared with IFT between the pure surfactin solution and oil. Trisodium citrate however caused significant permeability reduction on the injectivity tests whereas citric acid could be injected into the core without permeability reduction. The high pH value of trisodium citrate solution might cause the dissolution of ferrum and aluminum in the core and the colloids of ferrous hydroxide and aluminum hydroxide were formed in the core, which brought the significant permeability reduction. Citric acid was selected as the best inhibitor and subjected to the core flooding experiments. 25 % of oil remaining after primary recovery was recovered by injecting the solution containing 0.3 wt% of surfactin, 0.6 wt% of citric acid and 900 ppm of calcium ion. Rise in the differential pressure was not found during the injection of the solution, which suggested that citric acid was effective for inhibiting the precipitation in oil reservoir. Moreover, 25 % of recovery factor was 5 % higher than the recovery factor obtained by injecting pure surfactin solution. Citric acid is also effective for enhancing the surfactin capacity for increasing the recovery factor.
Citric acid has dual role as the binding inhibitor and co-surfactant. Because citric acid is environmentally friendly and cheap chemical, it can be promising additive which increase the applicable reservoir and potential of surfactant EOR.
New Borehole Image Log Based Technique for Pore System Characterization Predicts Productive Intervals in a Tight Carbonate Reservoir in Abu Dhabi
Authors: Noufal Abdelwahab , Obaid Khalid , Al Blooshi Abdulla , Nehaid Hani , Basioni Mahmoud , Alward Wassem , Uruzula Jaja , Shamsal Sudipan , Dasgupta Suvodip , Raina Ishan , Schlicht Peter 
Published: November 2018

Abstract
Carbonate reservoirs of the Middle East are known for exhibiting highly heterogenous nature in terms of reservoir properties within microscopic intervals of the reservoir, making it difficult to characterize and predict. An integrated approach involving detailed understanding of the fluids volumes porosity distributions, permeability systems, rock textures, reservoir rock types, and natural fracture distribution at different scales is needed. Accurate characterization for the flow networks, complicated by fracturing and diagenesis is fundamental to achieving realistic prediction, better production performance, and increased recovery. The rock texture in carbonate reservoirs is very unstable and continuously undergoing to multiple stages of dissolution, precipitation, and recrystallization, which obscures any relationships that might have existed between depositional attributes, porosity, and permeability. Fractures make it more complex with their different morphology, often further convoluted by leaching through them. Different measurements are needed to build a realistic model of the petrophysical properties of a carbonate formation. The standard resistivity and porosity measurements are often not sufficient to resolve changes in pore size and texture, so additional measurements are required. Workflows using borehole images can be used to extract information on different textural elements and porosity types. With the newly introduced workflow secondary porosity types are distinguished from matrix porosity and proxies for permeability are calculated.
This workflow integrates borehole images and other petrophysical data in sequential steps and provides important reservoir parameters. With the suggested analytical workflow, it is possible to classify the different types of pore space such as connected to vugs (vug to vug), isolated, connected to fractures, aligned at bed boundaries, or within the rock matrix. The contribution of these different pore types to the total porosity of the formation is quantified in addition to the geometric information of different types of heterogeneities. In addition, the connectedness of the different types of porosity is quantified. The connectedness log describes the quantity of connected spots detected from the electrical borehole image and is used as a predictive measure for identifying zones of higher or lower permeability. During operation it serves as an indicator for determining the perforation intervals, in static reservoir modeling it serves as a permeability driver to improve reservoir mapping. We demonstrate an example where the connectedness successfully predicted productive zones, proven by production logging.
Pre-Magnetization of Transformers
Authors: Abouelmakarem Mohamed , Kotrappa Murugendrappa , Al Ammari Sara , Manna Malay , Santhanamuthu Thenarasu , Sundaresan Hemachandran 
Published: November 2018

Abstract
Power supply in Oil & Gas offshore fields is very important to ensure production continuity; Pre-magnetization Transformers were introduced to avoid/reduce serious disturbances and voltage dips that may lead to blackouts when switching on Transformers at random instants.
Power transformers are generally energized by closing the circuit breaker at random instants. Consequently, the voltage of the supply system is also applied on the transformer windings at random instants. This switching usually introduces an asymmetrical magnetic flux in the windings that can drive the transformer into saturation. As a result, transient magnetizing inrush currents of high magnitude are generated in the transformer, which may cause serious disturbances leading sometimes into severe voltage dips or resulting in a complete blackout especially in weak grids such as remote offshore power networks.
With reference to figure 1 (Gonzalez et al, 2016), it can be seen that the worst case scenario would during close the circuit breaker at zero voltage level. This will cause the flux to peak up 2 times its normal operation causing the saturation of the core and asymmetrical inrush currents. Point on Wave controllers may be used to limit these effects. Figure 1Energization of Transformer at Worst Case Scenario
The design and installation of the Pre-magnetization transformers are described in this paper. One of the solutions for mitigating the high inrush current is to construct LV pre-magnetizing winding in the power transformers. This system involves initial energization of transformer core through LV pre-magnetizing transformer prior to connection of transformer primary to the main bus. This has the effect of pre-magnetizing the transformer’s core and aligning magnetic fields so that inrush is negligible when the primary feeder breaker is closed.
After careful evaluation of other technologies available like Point on Wave switching techniques … etc; Pre-magnetization of transformers is found to be highly secured solution which avoids all uncertainties due to critical nature of Oil & Gas Offshore Power networks.
A preliminary study has been done by using ETAP. This study clearly illustrated that electrical voltage drop is within the acceptable range after implementation of pre-magnetization transformer.
This paper describes the solution which was introduced for the first time in many different locations like natural islands, artificial island and Offshore Oil and gas Super Complex with integrated 132kV Subsea Power network. Rather than causing serious disturbances and voltage dips, this solution can be implemented in weak power grids to improve system stability.
Quantifying the Non-Monotonic Effect of Salinity on Water-in-Oil Emulsions towards a Better Understanding of Low-Salinity-Water/Oil/Rock Interactions
Authors: Gomez Sergio , Mansi Mohamed , Fahes Mashhad 
Published: November 2018

Abstract
Low-salinity water injection for EOR applications and for shale and tight sand fracturing has become a widely accepted approach. Experimental and modeling work is slowly unraveling the complexity of this system, with no unified theory to explain the fundamentals behind it. Our work adds a new spin to the topic, where the non-monotonic impact of salinity on contact angle reported in literature is linked to its non-monotonic impact on the properties of the water-oil interface.
We used a crude oil sample that originated from a field in Texas to create surfactant-stabilized brine-in-oil emulsions. We synthesized different brine systems starting from deionized water using two different salts, NaCl and CaCl2 at 8.55, 85.5 and 855 mMol/L. We quantified the stability of the emulsion using both gravimetric and centrifuge methods. We measured the variation in the viscosity of the emulsion for different brine fractions from 10 to 50 wt%.
The results show a different effect of salt on stability for different values of water-cut. This effect can range from a stability being directly proportional to salt concentration in one case, to being inversely proportional to salt concentration in the other case, including a scenario where a non-monotonic impact is recorded.
The work provides a comprehensive and detailed set of experiments on various measurements relating to the brine-oil interactions away from the influence of rock minerals. It shows similar trends to what is reported in the literature on experiments and simulations where carbonate and sandstone rock minerals are included. This brings to question some of the theories that are used to explain this behavior given that the complexity is evident even without the rock presence.
Alternative Operation Scheme for a Jackup Drilling Rig to Meet Target Soil Bearing Pressure Requirements
Authors: Beebe Tony , Vazquez Jose H. , Rousseau Joseph , Samuelsson Lars , Cunnion Pete , Coan Clay 
Published: November 2018

Abstract
The goal is to define conditions under which a GustoMSC CJ46-X100-D jackup rig designed for unrestricted service can be rated for full operational drilling capabilities in areas with a relatively weak soil top layer and a more benign environment. The GustoMSC CJ46-X100-D jackup rig is designed with environmental criteria derived from the southern North Sea and a bearing pressure of 53.5 MT/m2 (10.96 ksf); however, the maximum soil bearing pressure in some areas of the Arabian Gulf and elsewhere cannot exceed 41.5 MT/m2 (8.5 ksf).
Brownfield Survey Techniques Training and Development
Authors: Watson Kevin 
Published: November 2018

Abstract
An offshore survey is one of the key aspects in ensuring the successful implementation of any Brownfield project scope. When there are shortfalls in the offshore survey process, it can often lead to re-work offshore typically resulting in a substantial impact on costs and schedule.
For many years now, experts have predicted about extensive opportunities for Brownfield Projects in the Middle East (The Middle East Brownfield Projects Conference), sharing insights and strategies to rehabilitate mature, aged fields and depletion of well pressures. Clearly defines the Middle East's brownfield market as one of the region's high potential markets.
Oil & Gas Companies are fully aware of this and are constantly seeking effective, innovative, less complex ways to extend the lives of their existing facilities. Additionally, with oil prices falling to around $50 a barrel and with world vulnerability across the industry, our clients are under pressure to keep downtime to a minimum.
Permeability Derivation from Sonic Stoneley Wave Attenuation Measurements: Application in a Giant Carbonate Field from Middle East
Authors: Yin Hezhu , Wu Xianyun , Yose Lyndon 
Published: November 2018

Abstract
Permeability is one of the most important parameters that is required in reservoir simulation, field development, and reservoir management. An innovative permeability derivation method and workflow has been developed using Stoneley wave attenuation mechanism (not Stoneley wave velocity as discussed in some previous studies). The workflow was applied to the sonic waveform data acquired from a vertical well in a giant carbonate field in Middle East. The workflow includes (a) extraction of Stoneley-wave attenuation rigorously from the waveform data, and (b) fast inversion from Stoneley-wave attenuation to permeability.
Validation of the method and workflow were performed by comparing the results with core permeability and MDT mobility data. Results from this application indicate that low-frequency monopole waveforms provide good quality Stoneley wave data, and that Stoneley wave attenuation responds to permeability changes. The Stoneley-wave attenuation log extracted from the low-frequency monopole waveforms shows variability, and the permeability log obtained using the inversion workflow through different reservoir intervals has a good overall correlation with core permeability. The main reservoir interval is over 100 feet thick. Porosities are generally high throughout the interval, but permeabilities vary by several orders of magnitude due to pore type changes. The Stoneley wave attenuation permeability trend corresponds very well to vertical changes in the dominant pore system. Stoneley-derived permeabilities distinguish between microporosity in lower section with permeabilities in 1-20 millidarcy range, and mixed-pores in the upper section with permeabilities in the 10's to 100's of millidarcy range. The sonic permeability is also picking up tight streaks (stylolite zones with cementation) that have low porosity and permeability and can act as flow baffles within the reservoir. These results show that Stoneley wave attenuation is responding to changes in carbonate pore systems, and that Stoneley-derived permeabilities can provide useful permeability estimates in the absence of core data.
Engineered Flexible Expandable High-Density Cement System in Loss Prone High-Pressure Salt Section in Northern UAE
Authors: Sales da Silva Aguida , Schebath Dominique , Phyoe Thein Zaw , Kapoor Saurabh , Herrera Albuja Eduardo , Sajid Muhammad 
Published: November 2018

Abstract
The objective of a cementing operation is to achieve a long-term well integrity by providing good zonal isolation. In cementing operations in the northern part of the United Arab Emirates (UAE), thick salt formations, potential high-pressure zones, lost circulation zones and planned high pressure casing test added to the complexity of the cement job.
The presence of 3,000-ft or thicker salt formation posed a key challenge. The chemically reactive salts in the salt sections affects slurry placement and hydration. Salt from formation can be incorporated into cement slurry while placement and adversely affects the fluid loss, rheology, and setting characteristics. Thus, first, the cement system needed to be designed to be tolerant of such effects. Also, high pore pressure was expected while drilling so the planned mud density varied from 15.5 ppg to 18 ppg. The highest cement slurry density of 19.2 ppg was required to cover this wide range while maintaining the density hierarchy requirement for optimum placement. Additionally, a high-pressure test planned after the casing was set resulted in additional stresses, which also posed substantial risks to the integrity of the cement sheath.
A methodical approach was applied by first following the standard cementing practices and then categorizing the key factors in overcoming field specific challenges. Stress analysis using advanced software helped to identify the needed mechanical properties for the flexible and expanding cement system to remain intact under extreme pressure changes. After the in-depth lab testing, a fit for purpose compatible for placement against salt formation cement system was introduced. The use of engineered lost circulation fibers in the cement system would help to mitigate the losses during the cement job.
The engineered high-density salt compatible flexible expandable cement system was designed to provide the desirable outcome to the complex challenges. Comprehensive lab testing along advanced zonal isolation software helped in successful first-time execution.
The first-time application of this salt compatible flexible and expanding cement system has proven to be a robust solution for the cementation and could be the basis of design for all future wells industry-wide.
Integrating Real-Time Azimuthal Acoustic Data with Wellbore Stability Analysis for Safe and Fast Drilling, South & East Field, Kuwait
Authors: Belhouchet Mohamed , Al-Turkey Shaikha , Shah Bora Mir Alam , Al-Hindi Khaled , Al-Failakawi Fatma , Nair Abhilash , Elabsy Islam Mohamed , Abdessalem Abba 
Published: November 2018

Abstract
Before a well is drilled, the forces and stresses acting within a formation are in equilibrium. However, as the wellbore is drilled and a cylindrical volume of rock is removed, the stresses originally exerted on that volume must instead be transferred to the surrounding formation. The cylinder of rock is essentially replaced by a cylinder of drilling fluid, with its hydraulic pressure substituting for the mechanical support of the rock being removed. The hydrostatic pressure from the drilling fluid is uniform in all directions, and it cannot replicate any directional shear stresses that exist within the formation.
Formation stresses redistribute around the borehole wall, and if they exceed the rock strength, the borehole will start to deform. If the borehole wall itself begins to fail, the resulting problems could include stuck pipe, borehole wall breakout, swelling shales, and unintentional hydraulic fracturing.
The ability to predict and implement corrective action prior to any borehole problem occurring greatly reduces operational risk and ultimately increases operational efficiency. This is accomplished through the development of a geomechanical model which combines local geological and geomechanical field knowledge with comprehensive drilling and evaluation data from offset wells.
The geomechanical model provides the ability to predict and simulate wellbore stability of a planned well. Fields exhibiting considerable lateral heterogeneity and depositional variation can be challenging, but prediction and planning become more accurate as additional wells are drilled.
The well discussed in this paper was drilled with a bottomhole assembly (BHA) which included an azimuthal acoustic tool that enabled real-time wellbore stability analysis and equivalent circulating density (ECD) measurements to maintain an accurate mud-weight window. Real-time monitoring allowed predicted model responses to be confirmed, and/or the model to be updated.
The well was drilled to its final depth with no adverse borehole events, resulting in a quality borehole and a casing run with zero nonproductive time (NPT).
On the Pressure Response During Unsteady State Fluid Displacement Experiments
Authors: Mehana Mohamed , Fahes Mashhad 
Published: November 2018

Abstract
The pressure response observed during the unsteady state displacement is a critical factor in determining the steady value and contains valuable characteristics about the rock permeability and capillary pressure. Our objective is to elucidate the mechanism of the unsteady state displcment and its impact on the pressure reponse. We tried to match the experimentally-measured pressure profile using both numerical simulation and analytical solutions. Promising results are observed when the capillary pressure is considered. The results clarify that this response is not a function of gas compressibility or viscous fingering, but is directly linked to the ratio of liquid fractional flow to liquid relative permeability as a function of saturation. The relative permeability exponents have a direct role to play in this regard. This work highlights the inacpaibility observed in a reservoir simulator to capture the pressure signature. This brings into question the ability of such simulators to provide reliable data when it comes to model the displacement processes at the core-scale.
Electrification of Oil & Gas Offshore Installations with HVDC Submarine Cables
Authors: Toulotte Maxime , Lervik Lars , Renaudin Fabien 
Published: November 2018

Abstract
Electrification of Oil & Gas offshore installations can be performed by transmitting electrical energy over long length using high voltage direct current (HVDC) submarine cable systems. This paper describes the two commonly used technologies for HVDC submarine cable systems and the current state of the art. A technico-economical analysis has been performed for the supply and installation of an HVDC submarine cable system located in the Middle East, which shows that cable loss valuation should be considered together with the technology readiness level (TRL), in addition to the initial investment cost. Depending the voltage level, cross-linked polyethylene (XLPE) cables have a lower investment cost than mass impregnated (MI) cables, but considering the loss valuation and TRL, MI cables could be preferred considering the cable system only. This study gives an input to the full project value of an HVDC transmission system, where cost and losses of converter stations for different technologies and at various voltage levels should also be included.
Faster Restoration of Wells Using HWOU Snubbing Unit
Authors: Narwal Tushar , Busaidi Asaad , Ghenaimi Habib , Oguni Blessing , Abri Zahir , Benchekor Ahmed , Hadhrami Abdullah 
Published: November 2018

Abstract
In south-eastern part of the Sultanate of Oman, PDO is producing from one of Tight Sour Field (with H2S 1-2%) with current reservoir pressures ranging from 40,000 to 60,000kpa for more than 20 yrs. Due to tight nature of reservoir, the wells are hydraulically fracced to produce, but with time the production rates decline and wells start to produce in unstable mode. This unstable production mode leads to huge scaling and corrosion issues which results in tubing failures requiring huge and expensive workover to restore well production. Due to low production rates and expensive workover makes these intervention very less attractive in terms of Net Present Value (NPV) compared to other opportunities.
This paper describes the challenges in restoring production from wells with tubing leaks using conventional workover techniques and the advantages of using new approach of using Hydraulic Work Over Unit (HWOU/Snubbing unit) to workover these wells.
Using HWOU for workover restoration time from the failure to restoring production has been reduced from ~2-3yrs to almost less than a year along with significant reduction in overall cost (more than 40% per well). This approach has been successfully applied to 2 wells till dates and upcoming workover will be done in similar manner.