bluuebunny/crossref_metadata_2025 huggingface dataset:
Umbilical Cord Mesenchymal Stromal Cell With Autologous Bone Marrow Cell Transplantation in Established Type 1 Diabetes: A Pilot Randomized Controlled Open-Label Clinical Study to Assess Safety and Impact on Insulin Secretion
Authors: Cai Jinquan , Wu Zhixian , Xu Xiumin , Liao Lianming , Chen Jin , Huang Lianghu , Wu Weizhen , Luo Fang , Wu Chenguang , Pugliese Alberto , Pileggi Antonello , Ricordi Camillo , Tan Jianming
Published: December 2015

OBJECTIVE

To determine the safety and effects on insulin secretion of umbilical cord (UC) mesenchymal stromal cells (MSCs) plus autologous bone marrow mononuclear cell (aBM-MNC) stem cell transplantation (SCT) without immunotherapy in established type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Between January 2009 and December 2010, 42 patients with T1D were randomized (n = 21/group) to either SCT (1.1 × 106/kg UC-MSC, 106.8 × 106/kg aBM-MNC through supraselective pancreatic artery cannulation) or standard care (control). Patients were followed for 1 year at 3-month intervals. The primary end point was C-peptide area under the curve (AUCC-Pep) during an oral glucose tolerance test at 1 year. Additional end points were safety and tolerability of the procedure, metabolic control, and quality of life.

RESULTS

The treatment was well tolerated. At 1 year, metabolic measures improved in treated patients: AUCC-Pep increased 105.7% (6.6 ± 6.1 to 13.6 ± 8.1 pmol/mL/180 min, P = 0.00012) in 20 of 21 responders, whereas it decreased 7.7% in control subjects (8.4 ± 6.8 to 7.7 ± 4.5 pmol/mL/180 min, P = 0.013 vs. SCT); insulin area under the curve increased 49.3% (1,477.8 ± 1,012.8 to 2,205.5 ± 1,194.0 mmol/mL/180 min, P = 0.01), whereas it decreased 5.7% in control subjects (1,517.7 ± 630.2 to 1,431.7 ± 441.6 mmol/mL/180 min, P = 0.027 vs. SCT). HbA1c decreased 12.6% (8.6 ± 0.81% [70.0 ± 7.1 mmol/mol] to 7.5 ± 1.0% [58.0 ± 8.6 mmol/mol], P < 0.01) in the treated group, whereas it increased 1.2% in the control group (8.7 ± 0.9% [72.0 ± 7.5 mmol/mol] to 8.8 ± 0.9% [73 ± 7.5 mmol/mol], P < 0.01 vs. SCT). Fasting glycemia decreased 24.4% (200.0 ± 51.1 to 151.2 ± 22.1 mg/dL, P < 0.002) and 4.3% in control subjects (192.4 ± 35.3 to 184.2 ± 34.3 mg/dL, P < 0.042). Daily insulin requirements decreased 29.2% in only the treated group (0.9 ± 0.2 to 0.6 ± 0.2 IU/day/kg, P = 0.001), with no change found in control subjects (0.9 ± 0.2 to 0.9 ± 0.2 IU/day/kg, P < 0.01 vs. SCT).

CONCLUSIONS

Transplantation of UC-MSC and aBM-MNC was safe and associated with moderate improvement of metabolic measures in patients with established T1D.
Determinants of Diabetes Remission and Glycemic Control After Bariatric Surgery
Authors: Panunzi Simona , Carlsson Lena , De Gaetano Andrea , Peltonen Markku , Rice Toni , Sjöström Lars , Mingrone Geltrude , Dixon John B.
Published: December 2015

OBJECTIVE

Eligibility criteria for bariatric surgery in diabetes include BMI ≥35 kg/m2 and poorly controlled glycemia. However, BMI does not predict diabetes remission, and thus, predictors need to be identified.

RESEARCH DESIGN AND METHODS

Seven hundred twenty-seven patients were included in a database merged from the Swedish Obese Subjects (SOS) study and two randomized controlled studies, with 415 surgical and 312 medical patients in total. Bariatric operations were divided into gastric only (GO) and gastric plus diversion (GD).

RESULTS

Sixty-four percent of patients in the surgical arm and 15.0% in the medical arm experienced diabetes remission (P < 0.001). GO yielded 60% remission, and GD yielded 76% remission. The best predictors of diabetes remission were lower baseline glycemia and shorter diabetes duration. However, when operation type was considered, GD predicted a higher likelihood of remission and greater weight loss. Patients in remission (responders) lost more weight (25% vs. 17%) and waist circumference (18% vs. 13%) and experienced better insulin sensitivity than nonresponders.

CONCLUSIONS

Surgery is more effective than medical treatment in achieving diabetes remission and tighter glycemic control. Shorter diabetes duration, lower fasting glycemia before surgery, and GD versus GO procedures independently predict higher rates of remission, whereas baseline HbA1c and waist circumference predict improved glycemic control. The results show the advantage of an early operation together with better controlled glycemia on diabetes remission independently of BMI.
Breaking Up Prolonged Sitting With Standing or Walking Attenuates the Postprandial Metabolic Response in Postmenopausal Women: A Randomized Acute Study
Authors: Henson Joseph , Davies Melanie J. , Bodicoat Danielle H. , Edwardson Charlotte L. , Gill Jason M.R. , Stensel David J. , Tolfrey Keith , Dunstan David W. , Khunti Kamlesh , Yates Thomas
Published: December 2015

OBJECTIVE

To determine whether breaking up prolonged sitting with short bouts of standing or walking improves postprandial markers of cardiometabolic health in women at high risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

Twenty-two overweight/obese, dysglycemic, postmenopausal women (mean ± SD age 66.6 ± 4.7 years) each participated in two of the following treatments: prolonged, unbroken sitting (7.5 h) or prolonged sitting broken up with either standing or walking at a self-perceived light intensity (for 5 min every 30 min). Both allocation and treatment order were randomized. The incremental area under the curves (iAUCs) for glucose, insulin, nonesterified fatty acids (NEFA), and triglycerides were calculated for each treatment condition (mean ± SEM). The following day, all participants underwent the 7.5-h sitting protocol.

RESULTS

Compared with a prolonged bout of sitting (iAUC 5.3 ± 0.8 mmol/L ⋅ h), both standing (3.5 ± 0.8 mmol/L ⋅ h) and walking (3.8 ± 0.7 mmol/L ⋅ h) significantly reduced the glucose iAUC (both P < 0.05). When compared with prolonged sitting (548.2 ± 71.8 mU/L ⋅ h), insulin was also reduced for both activity conditions (standing, 437.2 ± 73.5 mU/L ⋅ h; walking, 347.9 ± 78.7 mU/L ⋅ h; both P < 0.05). Both standing (−1.0 ± 0.2 mmol/L ⋅ h) and walking (−0.8 ± 0.2 mmol/L ⋅ h) attenuated the suppression of NEFA compared with prolonged sitting (−1.5 ± 0.2 mmol/L ⋅ h) (both P < 0.05). There was no significant effect on triglyceride iAUC. The effects on glucose (standing and walking) and insulin (walking only) persisted into the following day.

CONCLUSIONS

Breaking up prolonged sitting with 5-min bouts of standing or walking at a self-perceived light intensity reduced postprandial glucose, insulin, and NEFA responses in women at high risk of type 2 diabetes. This simple, behavioral approach could inform future public health interventions aimed at improving the metabolic profile of postmenopausal, dysglycemic women.
The role of real time three-dimensional transoesophageal echocardiography in acquired mitral valve disease
Authors: Drąsutienė Agnė , Aidietienė Sigita , Zakarkaitė Diana
Published: December 2015

Real time (RT) three-dimensional (3D) imaging is one of the most significant developments of the last decade and is now being used with increasing frequency in echocardiography and interventional cardiology laboratories. Improvements in transducer technologies and the development of a matrix array transducer were the most important achievements that lead to the new era of real time 3D transoesophageal echocardiography (TEE). RT 3D TEE is ideal for assessing the mitral valve (MV) because of its high spatial resolution altering in improved MV anatomic detail. This imaging modality provides images of high quality which is of a great clinical value inmaking diagnosis of MV disease and a valuable tool for surgeons and interventional cardiologists in planning and guiding interventional procedures. This review is intended to provide data about normal MV anatomy and clinical usefulness of RT 3D TEE in defining acquired MV pathology.
Shear Tests and Calculation of Shear Resistance with the PC Program RFEM from Thin Partition Walls of Brick in Old Buildings
Authors: Korjenic Sinan , Nowak Bernhard , Löffler Philipp , Vašková Anna
Published: December 2015

This paper is about the shear capacity of partition walls in old buildings based on shear tests which were carried out under real conditions in an existing building. There were experiments conducted on different floors and in each case, the maximum recordable horizontal force and the horizontal displacement of the respective mortar were measured. At the same time material studies and material investigations were carried out in the laboratory. The material parameters were used for the calculation of the precise shear capacity of each joint. In the shear tests, the maximum displacement of a mortar joint was determined at a maximum of two to four millimetres. Furthermore, no direct linear relationship between the theoretical load (wall above it) and the shear stress occurred could be detected in the analysis of the experiment, as it was previously assumed.
Assessment of Soil-Structure Interaction in Seismic Bridge Pier Analysis Using Force and Displacement Based Approaches
Authors: Singh R N P , Vinayak Hemant Kumar
Published: December 2015

The seismic analysis carried out assuming foundation to be perfectly rigid and bonded to the soil underneath is far from truth and therefore, the soil-structure interaction effect on the dynamic behavior of the bridge pier should be considered. The assessment of soil-structure effect on the design force generated has been estimated using Force based, Capacity Spectrum and Direct Displacement based methods considering fixed and flexible foundations. For this purpose a single cantilever bridge pier of constant diameter with varying heights has been considered for the analysis in different type of soils and earthquake zones. The study has revealed that soil-Structure Interaction index is negative in some cases, especially in soft soil, implying base shear demand being greater than that of fixed base contrary to the traditional views.
Comparison of Vertical Light Wooden Constructions Insulated by Straw Bales
Authors: Kováč Miloslav
Published: December 2015

The main task of configuring engineer by designing enclosure construction is to setup performances of the wall to the best options for existing conditions of the structure. Selecting and adjusting bearing elements of perimeter wall is the first step, however appropriateness and position of chosen materials has major influence on technical properties and architectural expression of structure. Besides light vertical constructions (LVC) there are light wooden constructions from glued elements (LPVC), heavy vertical constructions (HVC) and prefabricated vertical constructions (PVC). All types have specifications allowing alternatives in terms of layer structure and bearing elements position. Each type is considered in terms of: structure – 2D drawing and 3D model, thermal insulation, overall heat transfer coefficient, architectural examination.
Journey Into Filter Cakes: A Microstructural Study
Authors: Li D. , He W.
Published: December 2015

Filter cakes are the key to maximizing return permeability and preventing formation damage. Typical considerations of filtercake properties include thickness, toughness, and slickness; however, a filter cake's structure, particle size distribution, texture, and invasion into the formation are also essential factors that can affect the production of oil or gas in a reservoir. This study was conducted to investigate filter cakes and its interactions with rocks through petrographic studies. The filter cakes were created via return permeability tests using actual reservoir or replaced cores. The information and data gathered increases understanding of the damage mechanism a fluid can have on the reservoir.

Our data demonstrates that an improperly sized bridging package, filter-cake compactness, filter-cake invasion, and the inability for a filter cake to create flow channels are key factors that significantly affect return permeability results. Undersized bridging particles can cause filter-cake invasion, permanently block pores within the formation, and limit production flow. Highly compacted filter cakes composed of fine-grained material could act as a barrier between the formation and the wellbore, which can result in a deceased return permeability measurement. Furthermore, filter-cake structures and homogeneity can indicate reservoir drill-in fluid (RDF) stability. Particle separation, according to grain size and/or density, in the drilling fluid can lead to graded particles within the filter cake; this can also ultimately affect production flow.
Investigating the Dominant Factors Influencing Well Screenouts for Crosslinked Fracturing Fluids in Shale Plays
Authors: Inyang U. , Cortez J. , Singh D. , Orth J. , Fontenelle L. , Kishore T.
Published: December 2015

One of the properties of guar borate complexed gel systems is the ability to recover dynamic viscosity after being subjected to high shear. This phenomenon is typically referred to as shear rehealing; and the ease of use of guar borate fluids during hydraulic fracturing operations can be partly attributed to this property. While many metal crosslinked fracturing fluid systems exist, and many provide higher proppant pack permeability after well cleanup, their overall use is lower because of higher cost, operational complexity, and perceived higher screenout rates. This paper examines laboratory and operational data to help parse the primary influences of screenouts for different fracturing fluid systems.

Extensive laboratory experiments investigating low to moderate shear viscosity tendencies of fluids as well as the low shear proppant transport properties of various fracturing fluid systems were performed to determine if there is a strong correlation between fluid flow properties and proppant transport under shear. The operational data reviewed includes wells with similar completion methods, such as completion tools and well construction methods, and the performance of the tested fluids in the field. Experimental data shows proppant transport under low to moderate shear is possible with all of the fluids investigated, and screenout rates did not show significant correlation to the type of fluid used. The decreased ability for shear rehealing is typically associated with higher bottom hole treating pressure and screenout rates of metal crosslinked fluid systems.

In many cases, operators are choosing simplicity of operations over the benefits of using higher quality fracturing fluids. This paper also discusses some of the factors that can help promote surface efficiency, while using the optimal fracturing fluids for the specific well.
Early Steps Towards Laboratory Evaluation of Diversion in Hydraulic Fractures
Authors: Cortez-Montalvo Janette , Vo Loan , Inyang Ubong , Parton Chris , Fulton Dwight
Published: December 2015

Advancements in diversion technology in recent years have made horizontal, multistage fracturing more reliable. Diversion treatments help generate and maintain complexity within generated fracture networks and can lead to more thorough reservoir stimulation. This facilitates maximized stimulation volumes and, potentially, increased production. With industry accepted benefits of the method, diversion technologies have been applied in both primary and refracturing operations. Even with broad adoption of fluid diversion techniques, limited reports of dynamic testing of diversion processes or chemicals under laboratory conditions exist. This paper describes a laboratory testing apparatus designed to dynamically probe the underlying mechanistic and chemical variables that influence near wellbore diversion against a consolidated proppant pack. This apparatus allows some of the critical parameters of diversion to be evaluated independently. In this study, early steps were taken to gain some understanding of the contributing parameters, such as diverter concentration, temperature, and pressure, and how they may influence diverter effectiveness. The laboratory setup in this study aims to conceptualize near wellbore diversion against a consolidated proppant pack with the ultimate goal of expanding the methodology to simulate real-life operation of a diversion treatment on fractures. This apparatus can help determine effects of chemical components and size distribution during successful diversion placement. In addition, some of the effects of temperature, pressure, and flow rates on diversion operations are presented. This dynamic study of diverters provided more insight into understanding factors that affect diversion, and provided data that can help optimize future diversion treatments.

It is widely acknowledged that diversion technology has significant impact in fracturing applications. By initiating the development of a viable lab scale apparatus for diversion chemical testing, greater understanding of how to implement optimized chemical formulations and engineering methods for more effective fluid diversion operations can be gained.
Borehole-to-Surface TFEM Technique Applications in Geologically Complex Areas
Authors: He Zhanxiang , Yu Gang , Zhao Guo , He Tiezhi
Published: December 2015

Borehole-to-surface time-frequency domain electromagnetic (TFEM) method has been applied in delineating oil/gas and water boundary. The technique has achieved significant improvements over the past 10 years and has become an important technique for oilfield development. Recently this method has been applied in a newly found oil and gas target in a mountainous area in the western plateau of China. Due to the complexity of the oilfield development area, some new technical measures have been taken when using the TFEM technique, such as multi-well joint operation program, multi-source excitement for multi-target layers, terrain correction, and then extracting effective induced polarization anomalies and high resistivity anomalies through dual frequency amplitude and tri-band phase anomaly. Drilling results have confirmed the effectiveness of the borehole-to-surface TFEM method in this oilfield. Based on the integrated interpretation result, confirmed oil-bearing areas within the oilfield are enlarged and provided very important basis for the selection of hydrocarbon reservoir delineation wells.

The borehole-to-surface TFEM survey results show that joint operation program of multiple source wells can evaluate relatively large area of traps. Multiple downhole source positions and graded source excitation can be used for detecting multi-target layers. A simple data processing method can depress terrain's effect, and then the high polarization anomalies and high resistivity anomalies reflecting hydrocarbon reservoirs are effectively extracted using the dual frequency amplitude anomaly and tri-band phase anomaly. Finally, potential hydrocarbon accumulation areas can be effectively evaluated and mapped. Drilling results have confirmed the validity of the method and this method provides an effective means for the delineation of hydrocarbon boundary and the selection of evaluation wells in newly developing oilfields.
Coupling Integrated Data Management with Reservoir Surveillance Workflows for Giant Mature Field in Qatar
Authors: Khalifa O. M. , Rais T. A. M , El Maadi A. , Abdullah Sani R. , Mahrous E. K. , Al-Marri Balsam
Published: December 2015

Dukhan, a giant mature onshore field in Qatar, presents a unique challenge to manage multidimensional data within surveillance workflows. A unified data infrastructure is the key enabler for proper field performance monitoring, bridging operational locations to decision-making centers. In this respect, Qatar Petroleum (QP) is integrating reservoir and data management workflows into a single hub that shifts linear workflows into real-time decision-making and action-oriented processes. The strategic advantage of this approach is to provide technology and data real-time, readily available for the key decision-makers. As a strategic initiative, implementation has presented unique challenges in infrastructure modification and technology uptake.

The envisaged solution architecture lies on capabilities of QP's workflows in delivering web components, leveraging multifunctional collaboration, and closing operational gaps within the surveillance workflows. The solution is delivered through a unified platform where periodic/sporadic production information is tied to asset operational models across different sub-systems integrating all surveillance workflows.

The benefits include a fully collaborative environment, a solid data management system to enable timely decisions, and improved shortfall management. Integrating people and processes with the right balance of technology results in enhanced operational efficiencies and recoveries. Despite challenges, QP has gained significant advantages in early adoption and development of this technology, and its implementation has revolutionized the approach to surveillance. In view of the above, the combination of the above aspects resulted in significant increase in compliances, minimized mitigation turnaround time and generated better collaboration within operating units.

This paper describes experiences and challenges of QP project from conception through implementation integrating people and process with the right balance of technology across field operations and how it has resulted in enhanced operational efficiency and production recovery with full asset awareness.
2 1/8-in. Intelligent Coiled Tubing System Improves Operational Efficiency
Authors: Livescu S. , Blanco D. A. , Vacik L.
Published: December 2015

A recently developed 2 ?-in. intelligent coiled tubing (ICT) system combines real-time downhole data monitoring with the capability to simultaneously provide downhole power, significantly improving operational efficiency and accelerating well recovery in all types of CT operations. From milling, stimulation, and well cleanouts to gas lifting, camera services, logging and perforating operations, this novel system can provide accurate, real-time downhole monitoring of high-resolution depth correlation, differential pressure, and temperature data.

The real-time ICT system consists of a non-intrusive electrical conductor wire, surface hardware and software, and a versatile 2 ?-in. bottomhole assembly (BHA) that incorporates the conductor release assembly, casing collar locator (CCL), pressure, and temperature sensor package, and BHA release function. Switching between different applications is as simple as changing out the BHA, which reduces the need to rig-up and rig-down and leads to operational time and cost savings. The main advantage of this system is that it eliminates the downhole uncertainties. For instance, using the real-time downhole depth, pressure, and temperature data, the CT field crew can react to changing conditions, make decisions based on dynamic downhole events, and eliminate missed or wasted runs.

Several case studies have been recently presented in an accompanying paper (SPE-174850). They involved an ICT conveyed camera operation in North America; a complex cement milling, cleanout, and perforating operation in Netherlands; an inflatable plugs setting operation in Brazil; a complex drifting, logging, jetting, zonal isolation, and scale removal operation in Brazil; and a matrix acidizing operation in Brazil. In this paper, several other representative cases are presented. First, an ICT system was used in a newly drilled well in Middle East to cut a stuck drill pipe. Second, an operation for creating a thief zone and matrix acidizing was performed in a deepwater well in Brazil. Third, a complex cleanout, milling, selective perforating, and acid stimulating operation was performed in a horizontal producer in North Sea.

The paper reviews the real-time ICT system and discusses the data acquired during these field operations. The system performance and benefits confirmed during the three operations are presented. These findings outline the versatility of the 2 ?-in. ICT system, the predictability of successful operations resulting from using this system, and the cost and time savings for operators.
Tapping the Difficult Oil and Enhancing Reservoir Development Strategy to Maximize Recovery From a Matured Waterflood Giant Carbonate Field in The Middle East: Arab C Reservoir Dukhan Field, State of Qatar
Authors: Majid Mohamed Naguib Bin Ab , Troconiz Carlos , Al-Shafei Mohammed Nedham , Luca Gheorghe , Cachi Ariel
Published: December 2015

After 70 years of production, more than 30% of the Arab C STOOIP has been recovered through various mechanisms including natural depletion, water flooding, gas-lift implementation and horizontal well development. Extending production into future years requires a strategic approach, focusing on innovative development optimization in order to target the remaining oil saturation. An aggressive drilling and intervention programme is ongoing to tap into the remaining oil. In addition to coupling evergreen reservoir models and flood-front surveillance, enhanced waterflood and CO2 WAG hold the greatest strategic potential to maximize recovery.

Integration of a recently acquired, high-resolution 3D seismic survey complements the data available for subsurface description and characterization, positively impacting reservoir model history matching metrics. Utilizing the models to set appropriate production and injection targets and vice versa adjusting the models to new data acquired in the field maintains a tight coupling between our models and surveillance monitoring. The evergreen models facilitate optimization of infill drilling locations targeting bypassed/remaining oil for sweep improvements.

Surveillance monitoring of flood-front encroachment and pressure behavior indicates that the permeable and connected beach and shoal lime grainstones of the Lower Arab C are sweeping according to simulation predictions. Conversely, the Upper Arab C exhibits a less favorable waterflooding potential due to the thin-bedded (1-2ft) grain- and mud-prone peritidal deposits that maintain significant lateral and vertical permeability contrasts. Sensitivity tests in our high-resolution full-field models support the addition of a line drive pattern to the existing peripheral waterflood for the Upper Arab C.

CO2 WAG has also been identified and tested in the model as a potential EOR mechanism to improve recovery. Engineering studies are underway to develop the infrastructural requirements for a CO2 pilot. It is envisaged that the combined development strategy of both enhanced waterflood and CO2 EOR will greatly assist in producing the difficult oil and maximizing recovery in the process.
Forward Process-Based Modeling of Submarine Turbiditic Environment: BC-10 OSTRA Case Study
Authors: Ferrandis Javier , Cantelli Alessandro , Jimenez Eduardo
Published: December 2015

Some of the current methods of geological modeling cannot imitate the order and complexity that is observed in nature. It's been recognized among the geoscientist community how a process-based modelling may facilitate a step change in reservoir building capabilities. The advantage in decoupling the grid design from the facies distribution poses a tremendous opportunity to close the gap between the static and dynamic reservoir model. A major advantage is capturing fine-scale heterogeneities (shale drape, amalgamation, etc) which are hard to capture with pixel-based techniques. The goal of process-based geological modeling is to simulate that order by generating rules. These rules make possible to create high-fidelity 3D geological models representing more realistic depositional and stratigraphic events than those that are randomly generated using conventional geostatistical techniques.

In this paper we illustrate the use of surface-based modeling within a submarine-turbiditic environment and the procedure followed to deliver a dynamic model conditioned to production data. The procedure follows development of physics-based methods and rule-base stacking of events to reconcile geological complexities and uncertainties with well performance. We'll present a process combining Design of Experiments and gradient-based techniques to assimilate production data. The method generates complex geometries comparable to those observed in high resolution near-surface seismic datasets. The case under consideration is an oil field offshore Brazil developed with horizontal wells and state of the art surveillance. The proposed workflow has delivered a simulation model that has achieved a good history match to production data in the form of water cuts and pressures.
Extended Abstract: Advanced Multiple Porosity Model for Fractured Reservoirs
Authors: Yan Bicheng , Alfi Masoud , Cao Yang , An Cheng , Wang Yuhe , Killough John E.
Published: December 2015

Much of the hydrocarbon reserves are stored in fractured reservoirs with high heterogeneity worldwide. In such reservoirs there likely exists more than two porosity types, and transient flow likely occurs in the matrix. Dual porosity models can characterize only two porosity types and are difficult to accurately capture the transient flow. This paper discusses an advanced model that allows simulating an arbitrary number of porosity types which accurately captures the transient flow in the matrix.

The proposed multiple porosity model honors any number of porosity types with different properties, such as permeability, porosity and wettability. Arbitrary connection for intra-porosity and inter-porosity flow are designed in an unstructured scheme, and convenient transformation between multiple porosity and multiple permeability formulations is allowed. A flexible porosity subdivision works in a fashion of hierarchical refinement and allows us to characterize the transient flow in the matrix and multilevel fracture sets with different geometry as well. The formulation is designed to allow the proposed scheme to be generalized. To quantify the improvement available with the new formulation, multiple porosity models are compared with single porosity models and analysis of different shape factors are also conducted. Our results show that they can be made to be equivalent under single phase conditions. Moreover, the application of the new model in shale reservoirs is discussed in two phase flow cases considering mixed wettability in shale matrix, and the results show that through a complete inter-porosity connection mode, the flow pathway of gas and water in shale is effectively identified.
A Novel Approach for Modeling Gas Flow Behaviors in Unconventional Reservoirs with Nanoporous Media
Authors: Song Hongqing , Li Zhengyi , Wang Yuhe , Zhu Weiyao , Cao Yang , Killough John
Published: December 2015

With the technology advancement in unconventional reservoirs development, more and more attention has been paid to nanoporous flow which is believed to play a central role in understanding fluid flow behaviors in unconventional reservoirs. Previous studies have performed unconventional reservoir analysis using more conventional reservoir simulation techniques. However, conventional numerical simulation techniques are computationally expensive and do not understand fluid flow behaviors well in terms of theory basis.

In this paper, we first present a new motion equation considering diffusion and convection and Lattice Boltzmann method is applied to model the gas flow characteristics to obtain the important parameters in the new general equation. Then the mathematical model of gas flow behaviors in multi-scale medium were proposed and established based on theoretical analysis of transport mechanism via molecular kinetic theory. The pressure distribution equations of radial and linear flow were derived for different flow regimes analytically, and the computation method of the control area of gas well was presented. Additionally, the semi-analytical equations of volumetric flow rate for horizontal fractured wells were obtained. At last through Newton iterative method, the non-linear volumetric flow rate was analyzed, considering various factors such as SRV permeability, unstimulated shale permeability, and diffusion coefficient.

Barnett shale production data is used to calibrate and validate this new approach. According to the results, the volumetric flow rate of the gas well increases when the diffusion coefficient grows. Consequently diffusion in unconventional reservoirs with nanoporous media plays an important role. With changing the average pore diameters, different results are simulated and calculated by LBM and the most appropriate values can be confirmed by comparing the experimental results. Besides, the intrinsic permeability of unstimulated shale and permeability of SRV are also found have apparent positive correlation with the gas productivity.
Innovative Integrated Asset Model including ESP Gas Handling and Power Supply Managements, Al Khalij Field case
Authors: Marmier R. , Elazabi S. , Viguerie B. , Pars H. , Venugopal D.
Published: December 2015

Since the start of production, the Al Khalij field, Qatar, has experienced a relatively rapid increase in water cut evolution and decrease in reservoir pressure. The associated consequences bring new challenges to the ESP development concept, increasing ESP exposure to free gas and power requirements. Therefore, operating and maximizing production of Al Khalij field requires not only integrated thermo-hydraulic fluid modeling from reservoir to surface, but also ESP gas handling and power supply managements. Integrated modeling is a cross-functioning simulation, monitoring and decision tool capturing the interactions from reservoir to surface facilities and from today to the end of field life. This paper describes the associated benefits of an innovative Al Khalij field Integrated Asset Model embedded into live data environment and performing production optimization accounting for ESP gas handling (gas volume factor and minimum bottom-hole pressure) and power supply management constraints (ESP motor, variable speed drive and wells and platforms transformers). As for any Integrated Asset Model, the reservoir, the wells, and the network thermo-hydraulic behaviors have been calibrated on the production data. The reliability of the well models to reproduce the measured production data has been demonstrated and is described in this paper. It has even proven capability to detect abnormal hydraulic and electrical behavior of the ESP motor and/or the pump. In the Integrated Asset Model, the intensity and voltage values are calculated at the ESP motor, the variable speed drive and the wells and platforms transformers levels. The electrical load based on these equipments design is used through an innovative workflow to constraint the field production optimization together with the free gas management constraints. The Integrated Asset Model has then been embedded into a live data environment of the field (DOF) for monitoring and automated models management and is used to further optimize the production including ESP free gas and power supply managements, and to anticipate on future debottlenecks.
Depositional Space: Construction and Applications to Facies and Petrophysical Property Simulations
Authors: Souche L. , Lepage F. , Laverne T. , Buchholz C.
Published: December 2015

In the absence of strong diagenetic or compaction trends, the anisotropy and distribution of facies and petrophysical properties are essentially the result of the composition of the paleoenvironment at the time of deposition and of geological phenomena such as erosion, faulting, and folding, which subsequently altered the geometry of the rocks. Understanding and isolating these two parameters (depositional and post-depositional effects) is key to the accurate interpolation and extrapolation of subsurface properties. This requires establishing a mathematical transform between the present-day geometry of rocks and their geometry at the time of deposition. The most common solution consists in relying on the layering and indexing of 3D grids to approximate paleodepositional coordinates. However, it is shown that for both pillar and stair-step grids in presence of tight folds or low-dipping or reverse faults, the variogram ranges, orientations, and facies proportions are significantly distorted when geostatistics are based on cell indexing.

Four essential properties that a rigorous depositional space should honor are then described and the shortcomings of the existing solutions are analyzed. A novel approach in which the representation of a depositional space is independent of a 3D reservoir grid is then introduced, and it is shown that solid mechanics provide a robust and practical way of building such a computational space. The use of depositional coordinates for performing variogram analysis and property interpolation is also exposed. The proposed approach yields facies distributions that accurately honor the model parameters independently from the structural configuration, while accounting for complex stratigraphic and depositional patterns (erosions, onlaps, etc.) and integrating nondepositional trends and overprints. We demonstrate that, in a variety of geological settings, better results are obtained when property interpolation and simulation do not rely on grid geometry and indexing.
Qualification and Optimization of Degradable Fibers for Re-Stimulation of Carbonate Reservoirs
Authors: Sau Rajes , Shuchart Chris , Clancey Byron , Lecerf Bruno , Pavlova Svetlana
Published: December 2015

Advancement in fluid diverter technology has enabled successful initial stimulation of long interval carbonates without mechanical isolation, in excess of 1000 ft. by using in-situ crosslinked polymer systems and viscoelastic surfactant systems. These fluids build viscosity upon reacting with the formation, enhancing diverter performance. However, heavily stimulated, i.e. wormholed, formations require a step-level change in diversion performance to effectively stimulation new intervals, or previously under-stimulated layers. This paper will present the qualification and optimization of degradable fibers for use in re-stimulation of carbonate formations.

The key performance aspects desired and evaluated are: (1) ability to block existing wormholes near the wellbore, as opposed to needing to fill the entire wormhole structure, (2) permeability and diversion capability of resulting fiber bridge, and (3) confirmation of degradation and cleanup in a dry gas environment within a reasonable timeframe. New experimental methods were developed to address these requirements, including gas/fluid degradation testing, bridging tests with slots to represent wormholes and fractures, and bridging experiments with 3D synthetic models of a wormhole structure. To be able to run repeatable experiments, wormholed structures were printed with a 3D printer using high-resolution CT scans from an actual wormholed core plug.

Testing results showed the ability of the fibers to bridge within the wormhole network and provided guidance in designing the fiber diverter stages for already-stimulated wells. Addition of degradable particulates was shown to further improve wormhole bridging and diversion performance. Modeling the wormhole diversion process within advanced stimulation software identified additional optimizations, such as increased stage size and increased fiber concentrations to achieve desired diversion. A related presentation will discuss the successful re-stimulation of three high-rate gas wells (B. Clancey 2015).
An Innovative Methodology for Real-Time Control and Optimization of Dual Injection Increases Efficiency of Carbonate Stimulation in Horizontal Openhole Water Injectors
Authors: Ramondenc P. , Burgos R. , Delgado E. Franco , Resendiz J. T.
Published: December 2015

An innovative methodology using a new bottomhole flow measurement tool and distributed temperature surveying was used to treat two openhole carbonate water injectors using coiled tubing (CT) equipped with fiber optics. The system capabilities were leveraged to control, in real time, the dual injection process and ensure that the treatment covered the entire horizontal section. The new level of efficiency of this approach was proven in the outstanding results of this stimulation campaign.

The method takes advantage of the fiber optics present in a CT string to acquire, in real time, both downhole flow measurements and distributed temperature surveys to identify areas of higher and lower injectivity along the wellbore. It also enables clear and rapid evaluation of the depth to the level that bullheaded fluid would normally reach downhole. The real-time flow measurement is further used to optimize the stages of the treatment that aim at placing fluid across the interval initially poorly covered, as it gives direct feedback of the efficiency of the pumping through the annulus and CT.

Matrix stimulation in water injector wells is often handled in a straightforward way by simply bullheading the treatment from surface. Used within the context of horizontal or highly deviated openhole wells, this frequently leads to an overstimulation at the casing shoe or along the first part of the zone of interest, and a significant section of wellbore is poorly covered or even remains untreated. The new approach not only enables visualizing where the treatment fluid goes, it also gives a new level of control of downhole injection, in real time. This new capability was taken advantage of within the context of long horizontal openhole water injectors, whose previous stimulation treatments left untouched a significant portion of the reservoir, even when complementing bullheading by the placement of treatment fluid with CT. The methodology enabled clear identification of which pumping method was beneficial to which interval. It also proved very efficient, leading to an increase in the injectivity index of the wells of nearly threefold, beyond the expectations based on previous stimulation interventions.

The new downhole flow measurement tool and its use within this innovative workflow address many limitations usually encountered during the stimulation of horizontal or highly deviated openhole water injectors. In particular, the approach enables taking full advantage of the dual injection process, which often proves difficult to control and optimize in real time. The end result is an unprecedented level of efficiency of the process.
Inter-Well Scale Sedimentological Heterogeneities And Facies Architecture Of Upper Jurassic Carbonate Reservoir And Anhydrite Seals: Lessons Learned Using Outcrop Analogues
Authors: John Cédric M. , Hönig Martin R. , Abbott Sunshine , Fraser Alastair J.
Published: December 2015

Most regional studies of reservoir and seals focus on large-scale sequences and their architecture. However, understanding flow and geochemical processes happening in the subsurface requires a multi-scale approach from the pore-size to the field-size. Here we focus on an intermediate, ‘inter-well’ scale loosely defined as 100-1000 meter scale. This inter-well scale is crucial as it represents the minimum distance between an injector and a producing well. Hence, constraints on the heterogeneities in the reservoir or within a sealing lithology can guide the production geologist during EOR or CCS operations. In this paper, we present a review of existing outcrop analogues for the subsurface of Qatar that were considered for our study. Out of the different possibilities, we selected outcrops from Wadi Naqab (Ras-Al-Khaima, UAE) as an analogue for the subsurface reservoirs in Qatar, and we focused on mine outcrops in the U.K. as potential analogues to derive the 3D geometry of evaporite-carbonate sequences analoguous to the Hith Formation. The Jurassic limestones at Wadi Naqab appear layer cake at the scale of observation, but we demonstrate here that even though beds rarely pinch out, the facies within bed changes markedly at a scale of <200 meters. For subsurface applications, this could be significant if the change in facies correlates with a change in petrophysical properties. The anhydrite layers at Brightling Mine are mostly composed of nodular, sabkha-type layers, inter-bedded with shallow-water algal limestones and shales. These lithologies are continuous at a 500 meters scale, but scouring impacts on the thickness of the deposits. Again, this could have important mechanical implications during CCS operations, because the interface of different lithologies and their thicknesses control fracture propagation within reservoirs and seals. We conclude that more geometrical heterogeneities exist in both reservoir and seals than previously thought, and that inter-well scale data are needed to inform subsurface reservoir models. We also caution that one of the limitations of using outcrop analogues is that porosity and permeabilities are not preserved during uplift, and thus petrophysical properties within numerial reservoir modelling need to be populated using subsurface data.
Advances in Application of Forward Osmosis Technology for Volume Reduction of Produced/Process Water from Gas-Field Operations
Authors: Minier-Matar Joel , Hussain Altaf , Santos Ana , Janson Arnold , Wang Rong , Fane Anthony G. , Adham Samer
Published: December 2015

Produced and process water (PPW) associated with gas production are often characterized by low total dissolved solids (TDS) and moderate organic content. The oil and gas (O&G) industry in Qatar currently practices disposal of PPW via deep well injection. To ensure long-term sustainability of the reservoir, Qatar operators aim to reduce the PPW disposal quantity by 50%. Recently, Qatargas had initiated a project to recycle process water and thus, reduce disposal volumes, by using commercial advanced water treatment technologies. For future projects/developments, the authors of this paper have proposed and evaluated, through funding by the Qatar National Research Fund (QNRF), an adaptation of forward osmosis (FO) membrane process for PPW concentration, which can be a cost-efficient alternative to achieve 50% volume reduction of PPW.

In the first step of conventional FO, a draw solution (DS) of high osmotic pressure is used as driving force to "pull-in" fresh water from the feed through a membrane into the DS. In the second step, and requiring significant energy, water is recovered from the regenerated DS by various methods depending on the DS used. In this project, brine from thermal desalination plant was used as DS and PPW as feed. Due to the salinity difference between the DS and the PPW, natural osmosis resulted in water permeating from the PPW into the DS, reducing the volume of PPW. Instead of recovering permeated water from the DS, the diluted DS can be directly discharged into the Arabian Gulf bringing an additional benefit by discharging lower salinity brine to the aquatic environment.

Commercial flat sheet membranes and hollow fiber (HF) membranes provided by Singapore Membrane Technology Centre have been tested through bench-scale experiments and the impact of various operating parameters such as DS concentration and temperature was investigated. Results indicated that FO can successfully treat the PPW to achieve the target volume reduction of 50%. The average flux for the HF membranes with pretreated feed was 17 L/m2-h (LMH) using 1M NaCl as DS. Organics passage from the feed to the DS was below detection limits which mitigates the potential concern of organics leaching into the Arabian Gulf.

Appropriate pretreatment of the PPW is required to minimize membrane fouling. Results showed a flux decline of approximately 10% over 5 hours when the PPW was used without pretreatment. The fouling was attributed to the organics present in the PPW. Different pretreatment options were evaluated to reduce membrane fouling including: ceramic membranes, activated carbon; and an organosilica adsorbent. To validate the project concept, long-term experiments were conducted mimicking field conditions. Overall, the results indicated FO is cost-efficient in reducing PPW injection volume and pilot testing is recommended to further demonstrate treatment feasibility of the process.