bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Mathematical Models to predict Preformed Particle Gel Placement and Propagation through Fractures
Authors: Fakher Sherif , Bai Baojun , Imqam Abdulmohsin , Wang Yanling
Published: October 2017

Preformed particle gel (PPG) treatments have been widely used in the industry in order to improve conformance by overcoming reservoir heterogeneity. In this study, several correlations have been generated and validated experimentally in order to model millimeter gel particles’, also referred to as PPG, propagation and placement in fractures, open hole plates, and void spaces. Three Experimental setups were used in order to study the factors affecting gel propagation in fractures, channels modeled by open hole plates, and void spaces modeled using tubes. The setups were used in order to study the effect of flow rate, fracture width, and gel strength on the resistance factor, and the gel injection pressure gradient. From the results, the data analysis was conducted using statistical tools to deduce if the three experimental models where consistent, and if so, generate three mathematical models, Resistance Factor versus the Shear Rate, Pressure Gradient vs Flow rate, and, Pressure Gradient versus Fracture Width. A validation of each correlation was performed using data not used in the generation of the correlations. A high accuracy fit was obtained during the validation of each of the correlations. The gel strength was included in all the newly developed models since it affects the gel propagation. This makes them a significant tool in order to accurately predict the pressure gradient of the PPG while it is being injected by simply knowing the particles’ gel strength, the flow rate used to inject the particles, and the fracture width. Pressure gradients, obtained using this correlation, were also plotted with pressure gradients obtained from in-situ gel injection. The correlation predicted higher pressure gradients than those of the in-situ gel, which is true since the particles are solids, whereas the in-situ gel is injected as a fluid. The resistance factor model was also used to validate a previously generated model that was used in the UTGEL Simulator. Based on the validation of all the newly developed mathematical models, they can be used to predict the gel particles’ injection and propagation through fractures, channels, and void spaces with high accuracy. This is a large addition in terms of PPG treatment since no previous models could accurately predict the gel placement and propagation in these reservoir features. By proving the accuracy of the models using the lab results these correlations can save largely on time by directly predicting the gel injection pressure gradient and resistance factors, rather than having to perform extensive lab experiments. Also, the correlations can help in properly performing a PPG treatment, while avoiding complications such as pump failure and formation fracturing.
Empowering Technical Professionals with Effective Soft Skills Leads to A More Successful Business
Authors: Dalrymple Lori Rene , Dalrymple Eldon Dwyann
Published: October 2017

Soft skills are a collection of people management skills. In the current economic atmosphere of the oil and gas industry, technical skills alone are insufficient for career success. Engineering professionals tend to prioritize technical skills over soft skills, however, the demands of their jobs require effective leading, speaking, listening, communication, collaboration, and conflict resolution "soft skills". The industry has had to make some very difficult decisions in the last few years. Many companies have opted to hire or retain technical professionals with excellent soft skills, who are adaptable, effective communicators, who are adept at collaboration and team management.

Technical skills and Soft skills if combined, create a synergistic effect that enables the technical professional to effectively communicate their needs or strategies. Being able to effectively communicate through confident speaking, listening, feedback, conflict resolution, critical thinking, and effective interpersonal skills create a positive environment that is conducive to a successful outcome through collaboration. Increasing numbers of University Petroleum Engineering Programs are beginning to add "soft skills" to their curriculum because they recognize the human to human skill factor is crucial to overall technical career success.

With the rigorous demands of the engineering curriculum, it is difficult for academia to provide adequate training in soft skills. This is one of the reasons that SPE has initiated a Soft Skills Committee, offering Webinars, Workshops, ATCE Sessions, Journal Articles, and Papers, to provide crucial soft skills training in the industry and to direct technical professionals to other avenues of training to enhance their abilities, thereby increasing their effectiveness in their chosen technical careers.

With the loss of over 350,000 jobs in the recent industry downturn, this paper the results of quantitative and qualitative studies which provide insight into the importance of soft skills and how they relate to the success of technical professionals. Data will be provided through industry market trends, professional studies of soft skills for engineer’s career success, and surveys of industry management. It will be illustrated that the blending of technical knowledge with effective soft skills abilities can increase the overall success of the engineer, and the success of the company.
Keeping Qualification and Competence Simple
Authors: Nuttall Kent R.
Published: October 2017

Competency programs currently focus on behaviors. Behaviors are difficult to measure, and are not directly associated with achievement of desired business results. By basing the programs on accomplishments, or work outputs, that are tied directly to desired business results, qualification and competence programs are simpler to use, more aligned and less subjective, and thus liberate behavior for more innovation.
Automated Geometric Path Correction in Directional Drilling
Authors: Joshi Deep R. , Samuel Robello
Published: October 2017

For a drilling engineer, designing and following an optimum well path is of foremost importance to ensure efficient wellbore placement. But the departure from a planned path is quite common. The objective of this research was to define algorithms to detect a well going off from a planned path and to find the most efficient corrective path to enable downhole directional automation. The closed-loop algorithms were examined using a hardware simulator and a software simulator.

The path correction algorithms combine survey calculation methods like Minimum Curvature, Balanced Tangential and Natural Curve methods with complex curves like a cubic spline, Bezier, Catenary, and clothoid to describe the corrective path. Here, the corrective path is divided into two sections. The curve properties like curve length, curvature and torsion are determined based on the location of the nodal point between these sections which in turn defines the Well Profile Energy or WPE of the curve. In this work, the WPE was chosen as the efficiency parameter because it considers both bending and twisting of a curve while providing a quantitative value which signifies efficiency of a curve. Combining a curve with a survey calculation method yields a unique well path corresponding to the minimum WPE for that combination and the most efficient corrective path will be chosen by comparing WPE for all twelve possible combinations of curves and survey methods.

To test the applicability of the path correction algorithms in a continuous downhole system, a MATLAB-based software simulator was designed. The dynamic deviation of the well due to factors like bit walk, formation heterogeneity, local stress regimes, bit walk and error in the directional drilling tools was applied using an arbitrary ‘Deviation Factor’. With its inclusion, we could simulate dynamic downhole drilling conditions in the simulator. Several parameters like maximum allowable curvature, torsion, maximum allowable inclination, allowable length of the corrective path were used to ensure a realistic, drillable path. Real-time application of the closed-loop algorithms was successfully examined by designing a hardware prototype controlled by a microcontroller. The directional changes were applied using two linear actuators and the resulting directional survey was recorded using a three-axis accelerometer.

This study provides three-dimensional algorithms for detecting when a well goes off path and finds the most efficient corrective path. The corrective path replaces the planned path and is continuously tracked for accuracy, making this a continuously closed loop system that, if combined with a MWD system, can enable an automated downhole directional drilling system.
A Comprehensive Model for Investigation of CO2-EOR with Nanopore Confinement in the Bakken Tight Oil Reservoir
Authors: Zhang Yuan , Di Yuan , Yu Wei , Sepehrnoori Kamy
Published: October 2017

CO2 injection is an effective enhanced oil recovery (EOR) method in unconventional oil reservoirs. However, the investigation of CO2 Huff-n-Puff in tight oil reservoirs with nanopore confinement is lacking in the petroleum industry. The conventional models need to be modified to consider the nanopore confinement in both phase equilibrium and fluid transport. Hence, we develop an efficient model to fill this gap and apply it in the field production of the Bakken tight oil reservoir. Complex fracture geometries are also handled in this model.

First, we revised the phase equilibrium calculation and evaluated the fluid properties with nanopore confinement. An excellent agreement between this proposed model and the experimental data is obtained considering nanopore confinement. Afterwards, we verified the calculated minimum miscibility pressure (MMP) using this model against the experimental data from rising-bubble apparatus (RBA). We analyzed the MMP and well performance of CO2-EOR in the Bakken tight oil reservoir. Based on the prediction of the field data, the MMP is 5.4% lower than the MMP with bulk fluid when the pore size reduces to 10 nm. Subsequently, we examined the impacts of key parameters such as matrix permeability and CO2 molecular diffusion on the CO2 Huff-n-Puff process. Results show that both CO2 diffusion and capillary pressure effect improve oil recovery factor from tight oil reservoirs, which should be correctly implemented in the simulation model. Finally, we analyzed well performance of a field-scale horizontal well from the Bakken formation with the non-planar fractures and natural fractures. Contributions of CO2 diffusion and capillary pressure effect are also examined in depth in field scale with the complex fracture geometries. The oil recovery factor of CO2 Huff-n-Puff process with both CO2 diffusion and capillary pressure effect increases by as much as5.1% in the 20-year period compared to the case without these factors.

This work efficiently analyzes the CO2 Huff-n-Puff with complex fracture geometries considering the CO2 diffusion and nanopore confinement in the field production from Bakken tight oil reservoir. This model can provide a strong basis for accurately predicting the long-term production with complex fracture geometries in the tight oil reservoirs.
Successful Application of Well Testing and Electrical Resistance Tomography to Determine Production Contribution of Individual Fracture and Water-Breakthrough Locations of Multifractured Horizontal Well in Changqing Oil Field, China
Authors: He Youwei , Cheng Shiqing , Qin Jiazheng , Chen Jianwen , Wang Yang , Feng Naichao , Yu Haiyang
Published: October 2017

It is observed that production rates decline quickly and water-cut rises to 90% only after two or three years’ production for many multifractured horizontal wells (MFHWs) in China. Reliable measurements are critical to assess production performance and diagnose water-breakthrough positions to arrange the subsequent operations (e.g. stimulation and water plugging). Although production-logging test (PLT) is an effective method for production performance evaluation, the MFHW might be scrapped during the test and PLT is also expensive for an MFHW. To solve this problem, this paper proposes an approach to determine the production contribution of individual fracture and locate water-breakthrough segments along horizontal wellbore by combination of well testing and electrical resistance tomography (ERT).

Firstly, a well testing model is developed to model pressure behavior of an MFHW intercepted by asymmetric fractures with arbitrary locations, unequal conductivity and production. Secondly, model validation demonstrates the accuracy of the well testing model proposed in this paper. Thirdly, sensitivity analysis shows that early-radial flow becomes remarkable as spacing between producing fractures or numbers of producing fractures decrease. N* is defined to characterize the number of mainly producing hydraulic fractures (NMPHF), and the value of N* depends on fracture properties (e.g. half-length, spacing, conductivity) besides the NMPHF. Fourthly, the well testing model is applied to estimate the flow profile through history matching of bottomhole-pressure (BHP) data. Fifthly, the introduction of ERT method solves the difficult to distinguish oil and water profile compared with well testing method, enables us to monitor the water-breakthrough locations and reduces the multiplicity of well testing interpretation in well performance evaluation.

Finally, this method has been successfully applied to Changqing Oil Field, and results obtained by well testing and ERT method coincide with PLT, which enable petroleum engineers to carry out stimulation strategies to improve production performance and decrease the water-cut of MFHWs.
Customizing Polymer Rheology for Application in Commercial Scale Polymer Floods
Authors: Fortenberry R. , Hernandez R. , Li Z. , Delshad M.
Published: October 2017

Reservoirs facing challenges such as high oil viscosity and high heterogeneity benefit from polymer flooding by decreasing unfavorable mobility ratios or improving crossflow. Despite this diversity of needs, polymer floods are often designed around a single point viscosity value, which doesn't account for variable shear rates in the porous media, in-situ viscosity, challenges with fluid injectivity, etc.

Polymers have diverse rheological characteristics. For example, synthetic polymers like HPAM are elastic and can range in their degree of shear sensitivity, while biopolymers like scleroglucan are inelastic and highly shear-thinning. We generated laboratory data for two such polymers, scleroglucan and an Acrylamide-ATBS Co-Polymer. We developed parameters to describe their rheological characteristics for a variety of models, including shear thinning, shear thickening and preshearing.

We then assessed the impact of these attributes on polymer flooding performance using UTCHEM, the University of Texas Chemical Flooding Reservoir Simulator. Polymer injectivity, viscosity, and shear rate were assessed for sensitivity to polymer rheology using simplified models of radial geometry. These results were correlated to laboratory experiments to ensure correct estimate of in-situ viscosities. Sensitivity to a variety of important parameters, including shear rate correction factor, simulation grid size, shear-thickening, and skin were also completed. A final sensitivity study was conducted using a heterogeneous reservoir model with the multiple patterns.

Simulations using the simplified radial model and the heterogeneous, commercial scale model support the same conclusion: the specifics of polymer rheology can have a significant impact on polymer flooding performance, and polymer rheology should be considered an important design attribute along with injection viscosity and retention. We show that injection of an elastic, HPAM-based polymer may require higher injection pressure or lower rates than a highly shear-thinning, inelastic biopolymer like scleroglucan. We also demonstrate how the differences in rheology impact reservoir pressure, in-situ viscosity distribution, in situ shear-rate distribution and flow into various reservoir layers.
Modern Completion Optimization in the Haynesville Shale
Authors: Cadotte R. J. , Whitsett Andrew , Sorrell Melfard , Hunter Ben
Published: October 2017

Haynesville Shale gas production (per day) decreased by half between late 2011 and mid-2016. This resulted from a combination of factors, including steeper declines in production per well than in other unconventional plays and reduced activity related to economic conditions. In 2016, however, drilling activity increased in the Haynesville Shale play as economic conditions improved because of higher natural gas commodity prices and new completion techniques were employed resulting in larger stimulated reservoir volume and more fracture initiation points along the wellbore.

Haynesville completions have continued to progress toward optimization, despite experiencing a lull in activity. Completion design parameters that have been altered to optimize production include lateral length, proppant volumes, proppant size, proppant type, and base fluid chemistry. Further, new technologies, such as intrastage degradable diverters and dissolvable plugs, have also been used to help increase production and improve asset utilization.

A comprehensive study was conducted comparing completion techniques used during original completions of early Haynesville Shale development to those deployed during the past year. The increase in normalized proppant volumes used per well is one of the most significant changes documented. By evaluating an acreage positon that was originally completed by multiple operators over a multiyear timeframe, an in-depth investigation of the impact of proppant volume on production in similar acreage can be completed. The effect of other completion parameters can also be evaluated.
After-Closure Idiosyncrasies of Fracture Calibration Test Analysis in Shale Formations
Authors: Marongiu-Porcu Matteo , Retnanto Albertus
Published: October 2017

Fracture Calibration Tests (FCT), are strategically used to estimate, amongst other important parameters, reservoir permeability and pore pressure during early appraisal stages of unconventional formations, where estimation of permeability and pore pressure by pressure transient buildup tests is impossible because no flow occurs without hydraulic fracture stimulation. This study investigates some of the idiosyncrasies that have been reported in a large number of FCTs, which make after-closure (AC) analysis ambiguous or inconsistent.

We recently introduced a novel comprehensive model for FCT analysis, combining before-closure (BC) and AC behavior in a fully consistent way, facilitating the detection of abnormal BC events (i.e. multiple closure and non-linear leakoff) and improving the intrinsic weakness of standalone AC analysis methods. Extensive use of this model on a vast number of shale gas FCTs has revealed the existence of apparent AC anomalies. This paper provides a novel approach to identify and diagnose these apparent anomalies and reconcile them with unique aspects of the tested unconventional shale formations.

In the AC anomaly that we firstly addressed in SPE-144028-MS, the logarithmic derivative shows only a minimal indication of formation linear flow, showing instead an abrupt transition to pseudo-radial flow. This unresolved anomaly inspired the work presented in this paper, where twenty FCT published case histories were used to study and reveal four distinct anomalies: –AC logarithmic derivative exhibits unit slope, a symptom of horizontal fracture;–Multiple closures followed by AC logarithmic derivative that exhibits a late-time "hook";–AC logarithmic derivative exhibits abrupt transition to pseudo-radial flow with limited or no linear flow;–AC logarithmic derivative exhibits an apparent dual porosity "dip".

These AC idiosyncrasies have been rationalized and integrated into our established comprehensive model for FCT analysis, allowing a realistic characterization of the geological, tectonic, and wellbore -related geometric signatures that very commonly manifest themselves in all shale formations.
Numerical Modeling of Proppant Transport in Complex Hydraulic Fracture Propagation
Authors: Izadi Ghazal , Hoeink Tobias , Cruz Leonardo , Copeland Dylan
Published: October 2017

Hydraulic fracturing is a stimulation technique used in unconventional reservoirs to generate sufficient reservoir contact for viable production. During stimulation, proppant is pumped into the system to keep fractures open when, at a later stage, injection ceases and fluid is recovered as fractures close. Thus, controlling proppant distribution in the fracture is important to improve well productivity. Several factors influence proppant placement and settling such as proppant size, proppant density and carrier-fluid rheology. However, accurately predicting, and consequently optimizing, proppant placement in complex fracture systems remains an industry challenge. The objective of this study is to use advanced modeling techniques of proppant transport inside complex fracture systems using a 3D simulator that couples geomechan ics, fracture mechanics, fluid behavior and proppant transport to assess the optimization of stimulation treatments. In this study proppant transport models incorporate the interaction between hydraulic fractures (HF) and natural fractures (NF) of various sizes and orientations. Treatments were simulated in systematic variations of proppant size, proppant density and fluid viscosity. Fluid rheology, proppant size and density are all major parameters affecting the proppant settling rate. In more complex systems, proppant placement is strongly influenced by the location, size, and orientation of natural fractures. Based on the size of proppant and viscosity of the injected fluid, proppant may or may not enter the natural fractures.
Maximizing CO2 Accumulation in Storage Reservoirs: Interplay between Permeability Retardation and Capillary Trapping of Rising CO2
Authors: Ren Bo , Delaney Jennifer M. , Lake Larry W. , Bryant Steven L.
Published: October 2017

The main objective of this work is to understand, by analytical and numerical study, how permeability retardation interacts with capillary barrier trapping to cause accumulation as CO2 migrates upward in saline aquifers during geological sequestration.

The study is of one-dimensional two-phase (CO2 and water) countercurrent flow. The analytical model describes CO2 buoyant migration and accumulation at a "flow barrier zone" (low permeability) above a "flow path zone" (high permeability). The relative importance of permeability retardation and capillary trapping is examined under different magnitudes of buoyant source fluxes and porous media properties. In the limiting case of zero capillary pressure, the model equation is solved using the method of characteristics. Permeability-retarded accumulation, induced by the permeability difference between the flow path and the barrier zone, is illustrated through CO2 saturation profiles and time-distance diagrams. Capillary trapping is subsequently accounted for by graphically incorporating a capillary pressure curve and capillary threshold effect.

Results demonstrate that the accumulation contributions from both the permeability hindrance and capillary trapping are convolved at sufficiently large fluxes. At a given time, the total CO2 accumulated is greater than for capillary trapping, but the former approaches the latter at large time. The low permeability zone need not be completely impermeable for accumulation to occur. We demonstrate that considering only capillary trapping understates the amount of CO2 accumulated beneath low permeability structures during significant periods of a sequestration operation.
A New Three-Phase Microemulsion Relative Permeability Model for Chemical Flooding Reservoir Simulators
Authors: Lashgari Hamid R. , Pope Gary A. , Tagavifar Mohsen , Luo Haishan , Sepehrnoori Kamy , Li Zhitao , Delshad Mojdeh
Published: October 2017

This paper presents a new three-phase relative permeability model for use in chemical flooding simulators. Numerical simulation test cases are presented to illustrate the continuity of the new relative permeability model. Comparisons are made with a three-phase relative permeability model that has been widely used in chemical flooding simulators for decades. These comparisons show the old model has numerical discontinuities that are not physical in nature and that can lead to oscillations in the numerical simulations. The proposed model is simpler, has fewer parameters and requires less experimental data to determine the relative permeability parameters compared to the original model. Simulations using the new model showed excellent agreement with ASP coreflood data.
Deployment of a Self-Adjusting Bit to Solve Todays Drilling Vibration Challenges and Optimize Performance
Authors: Phillips Anthony , Stefanik Thomas M.
Published: October 2017

For well over a decade, we have been using depth-of-cut (DOC) control to control the aggressiveness of polycrystalline diamond compact (PDC) bits. In recent years, the ability to change the aggressiveness has been an effective way of mitigating vibrations, in particular for stick-slip. The amount of fixed DOC control is determined for a particular formation or DOC, but it can limit performance in other parts of the well, or not solve vibration problems in multiple formations. This paper demonstrates that having a PDC bit with innovative self-adjusting DOC control can mitigate these vibrations to enable improved performance through each section of the well.

In the selected application in South Texas, torsional vibrations or stick-slip can be problematic, damaging the bit or downhole tools and reducing drilling performance. Performance metrics and dull conditions were collected to prove the presence of torsional dysfunction. Current bit styles have acceptable performance; however, the bit life has limitations regarding vibrations. Mitigating vibration is required to improve the performance of the bit and system. The addition of the self-adjusting DOC control feature changes the bit aggressiveness continually during the drilling operation, helping to achieve optimal performance.

When the self-adjusting feature engages with rock for steady state drilling, the feature gradually retracts, controlling the DOC to find the optimal exposure of the element for the current drilling parameters and formations. As dynamic instabilities occur, the self-adjusting feature reacts at fast time scales to mitigate the event. Comparing this technology to the offsets, the drilling data at surface show improved performance with 196% distance drilled while the downhole data show there is a smooth drilling response throughout the run.

A bit with the innovative self-adjusting DOC control can adapt to the downhole variables, prolonging its life and helping operators achieve their goals more efficiently, or with minimal driller intervention. Previously validating the concept in research wells it is now demonstrated in field trials with a reduction in torsional vibrations.
A New NMR-Based Method for Wettability Assessment in Mixed-Wet Rocks
Authors: Tandon S. , Rostami A. , Heidari Z.
Published: October 2017

Nuclear Magnetic Resonance (NMR) measurements can be used for quantifying rock wettability because they are sensitive to the type of fluids in contact with grains. Conventional experimental NMR-based methods for wettability determination often need NMR response for the same rock sample in different wettability states at irreducible water saturation and at residual oil saturation, which is time-consuming and could provide non-unique results. There also exist simulation-based methods for characterizing wettability in mixed-wet rocks. These methods either assume oversimplified pore shapes or require microComputed Tomography (CT) images of partially-saturated mixed-wet rock samples and complex image processing algorithms, which makes them computationally expensive. In this paper we introduce a new NMR-based wettability index for characterizing rock wettability and test its applicability in both carbonate and sandstone rock samples using numerical simulations.

The new NMR-based wettability index is a function of measured transverse magnetization (72) of mixed-wet rock, bulk relaxation and saturation of each phase, and simulated T2 distributions for fully water-saturated and fully hydrocarbon-saturated. We then use pore-scale simulation of NMR at different wettability states to verify the applicability and reliability of the newly introduced wettability index in rock samples with different pore structures including carbonate and sandstone samples. The first step in model verification is to obtain pore-scale images of few rock samples in each rock type in the formation. We then perform simulation of NMR T2 response for rocks with different wettability levels by numerically solving Bloch-Torrey equation using finite volume method. Then we generate mixed-wet synthetic samples, simulate the T2 response in the synthetic samples, and use the simulation results as inputs for determining their NMR-based wettability index.

The results demonstrate the reliability of the new NMR-derived wettability index. The introduced NMR-based method for wettability assessment allows for determination of wettability at any saturation state in the rock samples. It also eliminates the need for NMR calibration at irreducible water saturation and residual oil saturation and thus, might reduce the overall time required for determining wettability of mixed-wet samples. Successful application of the introduced workflow expedites assessment of wettability index and wettability changes in mixed-wet reservoir rocks.
Artificial Lift Applications for the Internet of Things
Authors: Elmer William G.
Published: October 2017

The term "Internet of Things" or IoT is bandied about by Information Technology professionals as the next great thing, yet do these people understand what happens at a producing well location? Are there artificial lift applications for devices similar to WiFi thermostats? Do they need to be connected to the "Cloud"? Who benefits most from application of IoT at the wellsite? What are the benefits to lease operators, field supervisors, and engineers?

An attempt to answer these questions will be performed by examining four actual IoT applications at real wellsites. The first is an example of "Pump Stroke Optimization" as introduced in SPE 181228 (Elmer 2016a), and the second and third examples pertain to SPE 181773 (Elmer 2016b), which dealt with an improved electric driven wellhead gas-lift compressor design. The aspect of their being IoT applications was not discussed in these original papers, but contributed to the success of these projects. A fourth example of IoT is the application to conventional three stage gas-lift compressors resulting in improved operations through precise temperature control and automation.

Engineers and field personnel will see examples of benefits achieved by combining IoT with engineering principles and operating personnel common sense, without need of the "Cloud". Not to denigrate the relevance of the "Cloud", the fact is that E&P operators insist on keeping their data securely maintained on their own servers. IoT applications are too valuable to delay implementation while debating the value of the "Cloud" and machine-based learning, when the IoT devices can instead use the operator’s private cloud. The multiple benefits of using IoT hardware that can readily communicate with normal Scada systems using Modbus protocol is also presented.
Estimation of Non-Uniform Production Rate Distribution of Multi-Fractured Horizontal Well Through Pressure Transient Analysis: Model and Case Study
Authors: Qin Jiazheng , Cheng Shiqing , He Youwei , Luo Le , Wang Yang , Feng Naichao , Zhang Tiantian , Qin Guan , Yu Haiyang
Published: October 2017

The severe decline of oil production has been observed in many multi-fractured horizontal wells (MFHW) within only one or two years. It is thus essential to determine production rate distribution of MFHW for improving oil production. However, available pressure-transient analysis (PTA) models of MFHW hardly consider the effect of non-uniform production rate distribution of both horizontal sections and hydraulic fractures on pressure-transient response, which may lead to erroneous results.

This paper aims at presenting an innovative approach to estimate non-uniform production rate distribution along horizontal wellbore in a relatively economical way. A novel model was proposed to better characterize flow in hydraulic fractures and horizontal wellbore. In order to better characterize pressure drops in hydraulic fractures, we first modeled fluid flow in fractures with finite conductivity by two parts, variable-mass-linear flow for fluid far from wellbore and radial flow for fluid near wellbore. Meanwhile, horizontal wellbore with finite conductivity was divided into multiple horizontal sections, and each section is considered as a cylindrical source. As a result, a semi-analytical solution was developed. We further compared it with numerical model to verify the accuracy. A new flow regime (the second radial flow) is discovered and behaves as a flat on pressure derivative curves. It would lead to erroneous results if the new regime is regarded as pseudo-radial flow.

Case study indicated that the production rate distribution obtained by the model proposed in this paper match well with production logging test (PLT), which validated the accuracy of the proposed approach and explored the feasible application in well performance evaluation of MFHW. In addition, operators could make reasonable decisions to improve well performance based on the evaluation results.
Enhanced Acid Fracturing with Improved Fluid Loss Control and Near Wellbore Diversion Increases Production in Kuwait
Authors: McCartney Elizabeth , Al-Othman Mohammad , Alam Anwar , Nino-Penaloza Andrea , Pirogov Alexander , Nagarkoti Malvika , Gupta D. V. , Mendez Alfredo
Published: October 2017

Excess fluid leak-off, a challenge in Kuwait's naturally fractured tight carbonate formations, can compromise post-fracture productivity. Past acid fracture treatments, both for moderate and high temperature formations failed to generate the long differently etched fracture due to excessive leak-off. Treating zones with multiple perforated intervals in a single stage, particularly in pay zones with long heterogeneous rock properties can result in non optimal stimulation. Therefore, a new approach was developed with proven success to enhance fracture conductivity and overall production by efficient control of fluid leak-off.

This novel approach incorporates the use of far-field and near-wellbore diverting systems into the acid fracture design. These solid particulate diverters (SPD) include low and high temperature systems that provide enhanced near-wellbore diversion in both case and open-hole applications. The SPD are designed to bridge across perforations and fractures in the higher permeability zones, diverting the stimulation fluid into lower permeability zones. A smaller sized multi-modal distribution of SPD controls the fluid in narrower natural fractures and wormholes, deepening penetration of the stimulation fluid along the entire fracture length. The SPD agents are fully degradable and do not contribute to permeability loss of the created fracture or the perforated interval when production starts.

The production of the wells where the SPD agents were applied were higher in comparison to expected production of offset wells where non-acid crosslinked fracturing pad stages alternated with gelled or emulsified acid, and visco-elastic surfactant (VES) slugs. Both crosslinked fracturing pads, VES and emulsified acid slugs do not effectly control live acid leak off.

Two case histories, documenting successes where this new approach to acid fracturing has been applied in the Tuba and Middle Marrat formations, have superior production results that correspond to enhanced fracture geometry.
Solving Losses and Increasing the Drilling Window in Depleted Zones by Continuously Strengthening the Wellbore
Authors: Falgout C. , Stefano G. De
Published: October 2017

The challenge of drilling through depleted zones, particularly in mature areas, continues to increase in importance as they are a frequent and familiar scenario for many fields. Pressure overbalances have been reported as high as 13,000 psi, although they more typically range in the hundreds to thousands psi. Wellbore stability problems associated with these zones can be linked to both drilling-induced and pre-existing fractures resulting in subsequent fluid losses. It is generally acknowledged that the solution to these problems is a combination of drilling fluid optimization and good drilling practices. Currently, the fluid solution is to incorporate large particulates in the form of a pill to seal such fractures, which consequently increases the drilling window. While the advantages of using a pill are known, large particulates also carry disadvantages, for example the retroactive nature of acting as a remedy rather than a prevention for lost circulation as well as leading to non-productive.

Formulations with various synergistic additives were examined through standard tests, including rheological profiles, high-pressure/ high-temperature fluid loss, and permeability plugging, some of which were performed on various porous disk media, including sandstone formation samples. Unique equipment was also developed and used to simulate a growing fracture mouth, or aperture, along with a proprietary mathematical model for the mechanism and geometry of fracture growth. The laboratory data supported a clear fracture mechanism and subsequent sealing, which was ultimately proven by yard test to confirm the laboratory and model predictions of performance.

Compared to commonly used particle packing/stress caging, the novel technology developed and testing performed demonstrates a new approach. The solution employs a continuous self-healing filtercake, rather than a large-sized lost circulation material pill application, to increase the drilling window and decrease risks of formation damage. The authors will present selected laboratory test methods and results, including a large scale fracture test and the associated mathematical modeling. This work shows a potential improvement in the drilling window while meeting environmental regulatory requirements in the Gulf of Mexico.
Proppants- What 30 Years of Study has Taught Us
Authors: Duenckel R. J. , Barree R. D. , Drylie S. , O'Connell L. G. , Abney K. L. , Conway M. W. , Moore N. , Chen F.
Published: October 2017

Hydraulic fracturing, when applied in concert with horizontal drilling, has led to a rejuvenation and revolution in the oil and gas industry that has been felt globally. When once development and reserve addition opportunities in the US were deemed to be very limited now technically recoverable reserves for both oil and gas in the US are viewed as abundant, and long-lived (EIA 2016). Yet hydraulic fracturing itself relies on the placement of proppants and the performance of those proppants to succeed.

The earliest hydraulic fracture stimulations utilized poorly sorted river sand as proppant. Since this first experiment with proppants, the industry has evolved with a broad range of proppant choices although natural sand of some type remains by far the proppant of choice for a variety of reasons. Technology has advanced in many ways since the first fracture stimulation. For the past thirty years, the Stim-Lab Proppant Consortium has engaged in a continuous program of building knowledge and understanding in the behavior of all types of proppants used in hydraulic fracturing.

Arguably no other body of knowledge about proppants exists that compares in extent and detail with that accumulated by the Consortium. There are many basic understandings about the behavior of proppant packs under downhole reservoir conditions that have been developed through thousands of tests that have been performed through the work of the Consortium. These include the effects of proppant type, grain failure, fines migration, embedment, non-Darcy and multi-phase flow, cycling, loading, packing arrangement, fracture fluid damage and others. All of these effects can be at work simultaneously to negatively affect flow in the propped fracture and the recognition of these effects assists to explain observed well performance.

This paper will present basic understandings of proppant performance that are sometimes misunderstood or wrongly applied and will assist the practicing engineer in well diagnostics and stimulation design. It will also present and describe predictive performance models developed for proppants that in turn leads to the most comprehensive simulation of proppant performance under realistic downhole conditions available in the industry.
Examining of immigrant entrepreneurship studies in international literature by using social network analysis
Authors: Akın Nisa , Bostancı Barış , Mayatürk Akyol Evrim
Published: October 2017

Immigrant entrepreneurship is increasingly becoming part of the global economy which is garnering more attention from different academic disciplines. The increase in numbers of immigrants all over the world, especially in recent times, has also led to an increase in the immigrant entrepreneurship. Socio-cultural and economic impacts of this increase begin to draw attention of researchers studying the economy and business. However, analyzing the studies about immigrant entrepreneurship phenomenon systematically is quite limited. In this context, the aim of the study is to reveal knowledge network of immigrant entrepreneurship and show slightly-used paths of this field as suggestions for further studies. To achieve this aim, social network analysis (SNA) providing linkages and connections about immigrant entrepreneurship is used. Likewise SNA method is commonly used in scientific researches to provide a powerful set of tools for describing and linking information. Articles about immigrant entrepreneurship published in journals which are involved in SSCI are evaluated and UCINET software is used for visualizing our research through keywords. The study is expected to contribute to the business literature generally and entrepreneurship literature specifically and lead to researchers who aim to study the immigrant entrepreneurship by means of focusing on gaps and variables which are not discoursed adequately in the field.
DART model from a customer's perspective: an exploratory study in the hospitality industry of Greece
Authors: Solakis Konstantinos , C. Peña-Vinces Jesús , Manuel Lopéz-Bonilla Jesús
Published: October 2017

The customers are an essential element for marketing decisions and became a factor decisive to develop collaborations with the company. The study examines the four building blocks of the interaction of the DART model (Dialogue, Access, Risk Assessment, Transparency) in the hospitality industry from the client’s perception. This approach of the research is paramount, as value co-creation and DART model especially are based on a dialogical process between equal partners. That means that the principles of the four building blocks of interaction are equally applied to all the actors involved. This argument is amplified as the dividing line between producers and consumers is barely evident in the service-dominant logic. The exploratory study has been carried out at the Makedonia International Airport in Thessaloniki, Greece. Partial Least Squares (PLS) provides empirical support to conduct the exploratory study.
Simulation analysis of low strain dynamic testing of pile with inhomogeneous elastic modulus
Authors: Xu Juncai , Shen Zhenzhong , Ren Qingwen
Published: October 2017

Low strain dynamic testing is an important nondestructive testing method in the engineering. However, the pile foundation material is usually assumed as having a uniform elastic modulus in low strain simulations. In this paper, we consider the elastic modulus of concrete as having an inhomogeneous elastic modulus that is described by the Weibull distribution model. An explicit algorithm was adopted in order to solve the model. The finite element method (FEM) was used to simulate the low strain dynamic test of a 3D pile. The response velocity characteristics of different shape parameters were obtained using this method, and the Daubechies wavelet transform was used to analyze the characteristics of the wavelet modulus. The result shows that simulation response velocity has a correlation with the different homogeneity of the elastic modulus.
Simulation technique of constant contact side bearings of freight car bogies
Authors: Adilkhanov Erzhan , Sekerovа Sholpan , Musayev Janat , Zhauyt Algazy , Yussupova Saltanat , Alimbetov Assylkhan
Published: October 2017

Actually, the side bearings of constant contact cabs are installed on freight cars of new design railroad gage of 1520 mm. Parameters of side bearing elastic elements have significant effect on dynamic behavior of the car and traffic safety. The article is devoted to comparison of side bearing of standard (rigid, shim) design body and bearings of constant contact by means of computer modeling.
Investigation the accuracy of FEMA-440 procedure to analyze soil-structure systems
Authors: Khanmohammadi Leila , Vaseghi Amiri Javad , Davoodi Mohammad Reza
Published: October 2017

A common analysis method of soil-structure systems in seismic design procedures such as FEMA-440 is to replace the entire soil-structure system by a fixed-base oscillator with an equivalent fundamental period and damping ratio to consider inertial effect of soil-structure interaction. It is generally believed by researchers that ignoring kinematic effect of soil-structure interaction is conservative to determine response of structures and FEMA-440 supports this idea by defining a reduction factor applying to elastic response spectra. Also, the improvements of nonlinear static procedures in FEMA-440 are achieved for fixed-base structures and the soil effects are not perfectly obtained in coefficients and relations of these procedures. Thus, it seems necessary to assess the accuracy of proposed procedures of FEMA-440 to include soil-structure interaction. In this paper, the accuracy of equivalent replacement oscillator and nonlinear static Procedures of Equivalent Linearization and Coefficient methods, defined in FEMA-440, to analyze soil-structure systems with surface and embedded foundations are evaluated. Both kinematic and inertial effects of soil-structure interaction are investigated by conducting a parametric study using 20 ground motions recorded on soft soil site E, on which the more SSI effects are probable.
Analysis of seismically induced vibrations in turbo machinery foundation for different soil conditions: case study
Authors: Tripathy Sungyani , Desai Atul K
Published: October 2017

The effect of poor soil condition and unbalanced weight of the turbo machineries can lead to increased amplitudes of vibration which are further multiplied if subjected to seismic loading. In the current work, a computational model for the turbo machinery foundation was developed in SAP 2000 software to analyze the effect of Kathmandu earthquake (2015) in five different soil conditions i.e. very hard generic rock, generic rock, generic soil, NEHRP C class and NEHRP D class. The results reveal that turbo machinery foundation with barrettes can be used in seismic areas as barrettes safeguard the foundation by absorbing/reducing the seismic load due to high specific surface and side resistance. However for poor soil conditions like NEHRP D (clay soil), it was found that barrettes alone are not sufficient to limit the vibrations induced by either dynamic loading due to rotating motion of the machineries or seismic loading. Applications of geosynthetics along with barrettes considerably reduce the vibrations at top deck for poor soil conditions.