bluuebunny/crossref_metadata_2025 huggingface dataset:
Hole-Cleaning Optimization: A Case History from Three High-angle Wells in Austria
Authors: Thompson John , Wilkes John , Marland Chris , Martin Antony , Bindl Benedikt , Brunneder Michael
Published: April 2015

Hole cleaning is a critical part of ensuring successful execution, as wells become more challenging to drill and well designs more complex.

The philosophy of model, measure, and optimize was applied to the task. Three consecutive, similar, and co-located high-angle (85–95°) 8-½-in. sections were drilled, which provides an objective comparison of the efficacy of effective and consistent drilling practices, teamwork, and engineering.

The operator's challenge was to: Mitigate the risk of stuck pipe during drilling and tripping,Reduce the need for backreaming to reduce potential for excess wellbore and down-hole tool damage, andDeliver efficiency savings.

The primary aim to execute these deliverables meant ensuring effective hole cleaning while drilling and prior to tripping to facilitate a clean, uneventful trip out of hole.

During the planning phase, the hydraulics system and the torque and drag were initially modelled to give a baseline measurement to assess the drilling operations and were continually updated to ensure accuracy. Additionally, modelling highlighted a major contributor to previous hole-cleaning issues from the drilling fluid.

During the execution phase, drilling and tripping practices already in place drew particular scrutiny, which lead to a discussion between the operator and service provider. Proactive operator leadership led to collaboration with the service provider to review the practices and procedures. This collaboration resulted in presentations for rigsite personnel to emphasize the importance of standardized procedures and to lead to subsequent improvement in each well.

This case study investigates each section's performance and the positive results from procedural improvements, mud-property optimization, and cost savings of proper hole cleaning, which resulted in the following:No stuck-pipe/lost-tool incidents,Ability to pull on elevators at the final TD of the third well,63% improvement in tripping-out time at TD (comparing Well 3 to Well 1, 15 hours compared to 40-½ hours), and15% improvement in liner-tripping time.
Interactive Web Based 3D Wellbore Viewer Enables Collaborative Analysis
Authors: Phillips Walter
Published: April 2015

Common wellbore visualizations are depicted using 2D perspective views. This approach is limited and potentially misleading. Of particular interest to rod-pumping and progressing cavity pumps is the amount of side loading placed on the rod string throughout the wellbore. By illustrating the trajectory of a wellbore in 2D, some nuanced geometries can be easily lost. The familiar “corkscrew” wellbore, for example, is very difficult to depict through simple perspective views. A corkscrew is best visualized at a specific camera angle where the shape is apparent. This best viewing angle is generally not at 90 degrees, where typical 2D perspective views are generated.

Distributed wellbore visualization tools can be applied to both design and analysis of pump installations. Interactive views help to identify points in the well where problems may occur, or have occurred. Strategic placement of downhole equipment such as pump depth relative to perforations and historic fluid levels can be done in a more intuitive way, taking into account a more accurate understanding of the wells geometry.

The use of standards based modern web technologies enables rapid deployment of such a tool to both desktop and mobile devices. Three dimensional graphics acceleration was previously only available in the web browser through plugins and other 3rd party software installations. 3D graphics can now be rendered natively in most modern web browsers without the need for any additional software.
Imaging-Aided Study of Relative Permeability Response to Temperature in Diatomaceous Rocks
Authors: Vega Bolivia , Kovscek Anthony R.
Published: April 2015

Relative permeability, and its temperature dependence, is one of the most important and often adjusted physical relationships during history-matching of thermal oil recovery projects. To increase understanding of oil-water relative permeability behavior as a function of temperature, we conducted and interpreted laboratory-scale experiments. In these studies, high-temperature, spontaneous and forced isothermal water imbibition tests were conducted on diatomaceous reservoir core samples of clayey and sandy types. Tests were carried out at temperatures of 45 and 230 °C (113 °F and 446 °F). Tests included spontaneous counter-current water imbibition followed by forced co-current water imbibition to residual oil saturation. Wettability shift was assessed experimentally through the Amott index. Dependence of endpoint phase saturation and relative permeability on temperature was also apparent. The wettability response observed indicates wettability transition to greater water-wetness with increasing temperature. X-ray computed tomography imaging provided the 3D distribution of porosity and aided us in following the spatial distribution of water saturation as a function of time in the samples throughout the imbibition process. Water saturation evolution varied among samples. Front-like water advance and more or less uniform imbibition were measured. Heterogeneity at the core scale was evident in both porosity and water saturation images. A commercial simulator was used to model and to history match core-scale flow behavior. Relative permeability curves were created consistent with the experimentally found oil and water relative permeability endpoints. Importantly, a heterogeneous wettability distribution was incorporated in one case to match experimental observations. Study results include relative permeability curves and wettability indices as a function of temperature.
Practical Application of Data-Driven Modeling Approach during Waterflooding Operations in Heterogeneous Reservoirs
Authors: Amirian Ehsan , Chen Zhangxin
Published: April 2015

Quantitative assessment of different operating areas and uncertainty appraisal due to reservoir heterogeneities are crucial elements in optimization of production and development strategies in oil sands operations. Evaluation of waterflooding performance that involves detailed simulations is usually deterministic, cumbersome, expensive (manpower and time consuming), and not quite suitable for practical decision making and forecasting, particularly when dealing with a high-dimensional data space consisting of a large number of operational and geological parameters. Data-driven modeling techniques, which integrate a comprehensive data analysis and machine learning methods, provide an attractive alternative especially for extremely nonlinear system forecast.

In this paper, an exploratory data analysis is applied to construct a comprehensive training data set from waterflooding field data, which entails various attributes describing characteristics associated with reservoir heterogeneities and other relevant operating parameters. Artificial neural network (ANN) is employed as a data-driven modeling alternative to predict waterflooding production in heterogeneous reservoirs, an important application that is lacking in the existing literature. ANN utilizes a training data set to identify all significant patterns and relationships that exist between the input and output attributes. The data-driven model is subsequently tested using a verification data set involving cases that have not been used at the training stage.

This paper highlights the great potential of data-driven modeling techniques for practical applications and to be used as a viable tool for analyzing a large amount of competitor data efficiently. In addition, the proposed approach can be integrated directly into most existing reservoir management routines. Given that robust forecasting and optimization of heavy oil recovery processes is a major challenge faced by the industry, the proposed research also has great potential to be applied in other recovery projects such as steam assisted gravity drainage (SAGD) and solvent-additive steam injection.
An Experimental Investigation of Viscous Oil Recovery Efficiency as a Function of Voidage Replacement Ratio
Authors: Kim Tae Wook , Vittoratos E. , Kovscek A. R.
Published: April 2015

Recovery processes with a voidage replacement ratio (VRR=injected volume/produced volume) of 1 rely solely upon viscous forces to displace oil whereas a VRR of 0 relies upon solution-gas drive. Activating a solution gas drive mechanism in combination with waterflooding using periods of VRR less than 1 (VRR <1) may be optimal for recovery. Laboratory evidence suggests that recovery for VRR <1 is enhanced by emulsion flow and foamy oil at pressures under bubble point for some crude oils. This paper investigates the effect of VRR for two crude oils referred to as A1 (88 cP and 6.2 wt% asphaltene) and A2 (600 cP and 2.5 wt% asphaltene) in a sandpack system (18 ʺ long and 2 ʺ dia.). The crude oils are characterized using viscosity, asphaltene fraction, and acid/base numbers. A high-pressure experimental sandpack system (1 Darcy and Swi=0) was used to conduct experiments with VRR's of 1.0, 0.7, and 0 for both oils. During waterflood experiments, we controlled and monitored the rate of fluid injection and production to obtain well-characterized VRR. Based on the production ratio of fluids, the gas-oil and-water relative permeabilities were estimated under two-phase flow conditions. For a VRR of 0, the gas relative permeability of both oils exhibited extremely low values (10-6 ~ 10-4) due to internal gas drive. Water floods with VRR < 1 displayed encouraging recovery results. In particular, the final oil recovery with VRR=0.7 (66.2 % OOIP) is more than 15% greater than that with VRR=1 (55.6 % OOIP) using A1 crude oil. Results for A2 with VRR=0.7 (60.5 % OOIP) were identical to the sum of oil recovery for solution gas drive (19.1 % OOIP) plus waterflooding (40.1 % OOIP). An in-line viewing cell permitted inspection of produced fluid morphology. For A1 and VRR = 0.7, produced oil was emulsified and dispersed as gas bubbles, as expected for a foamy oil. For A2 and VRR <1, foamy oil was not clearly observed in the viewing cell. In all cases, the water cut of VRR=1 is clearly greater than that of VRR=0.7. Finally, three-phase relative permeability was explored based upon the experimentally determined two-phase oil-water and liquid-gas relative permeability curves. Using well known algorithms for three-phase relative permeability, however, did not result in good history matches to the experimental data. Numerical simulations matched the experimental recovery versus production time acceptably after modification of the measured krg and krow. The degree of agreement with experimental data is sensitive to the details of gas (gas-oil system) and oil (oil-water system) mobility.
Technology Qualification and Installation Plan of Efficient and Accurate Multilaterals Drilling Stimulation Technology for Sandstone Oil Application
Authors: Rice Kevin , Jørgensen Thomas , Solhaug Kristian
Published: April 2015

Most reservoirs cannot produce efficiently without stimulation. Multilateral wells are known to increase productivity but can be time consuming and challenging to implement. Stimulation methods such as hydraulic fracturing can be complex to deploy and difficult to direct. Multilateral stimulation technology (MST) used to stimulate carbonate reservoirs with efficiency and accuracy has been well documented through the concept, development and field trial stages (Freyer et al 2009, Freyer et al 2011, Rice et al 2014, Carvajal et al 2015). This paper will discuss the evolution of a new multilateral stimulation technology which has been developed and qualified as part of a Joint Industry Project (JIP) with Fishbones, Statoil, ENI, Lundin and Innovation Norway. The technology increases oil recovery rates from tight formations by means of an efficient pumping process which creates accurately placed laterals into the formation. Previous MST systems utilize jetting action along with the chemical reaction between hydrochloric acid (HCl) and carbonate formations to create the laterals. This paper will discuss the further progression of this technology to qualify a new method known as multilateral drilling stimulation technology (MDST), which can be applied in non-reactive formations and in those that are otherwise inefficient to jet. The MDST utilizes the existing fluid system in the wellbore and standard rig pumping equipment to create a significant number of pathways into the reservoir. The qualification testing to the current status of Technology Readiness Level 4 (TRL4), Qualified for First Use, will be discussed along with the reservoir simulation and installation planning for downhole deployment.
Fast Production Optimization with Decline Curve Analysis Under Facility Constraints: A Field Case Study
Authors: Kritsadativud P. , Jafarpour B. , Ekkawong P.
Published: April 2015

Production optimization can play a major role in increasing recovery and decreasing operation cost. In many oilfields, the geology, production operations, and their related constraints are very complex. These complexities can complicate the formulation and solution of the pertinent optimization problems and increase the computational cost of finding a solution. Although full reservoir simulation provides detailed analysis and prediction of reservoir performance, the significant uncertainty and complexity of reservoir models can make the simulation results and their interpretations questionable. Moreover, in some cases, a reservoir model may not even be available to perform full simulation for performance optimization. The cost and complexity of developing full-scale simulation models, together with the considerable computational overhead associated with production optimization (especially under geologic uncertainty), call for development of fast proxy models for production optimization. To this end, various reduced-order and surrogate models have been designed to approximate the production behavior of a reservoir at a fraction of the computation required for full simulation.

We present an efficient production optimization scheme by integrating constrained optimization with fast decline curve analysis for predicting well production performance. The proposed production optimization approach is formulated as a constrained optimization problem by defining a desired objective function and a set of existing field/facility constraints. An efficient gradient-based optimization algorithm is then adopted to solve the resulting optimization problem for a single timestep. The optimization is then coupled with the decline curve analysis to predict future production rates. The optimization process is performed recursively in time for a specified duration. The predictions with the decline curve analysis are reasonable so long as the operating conditions remain unchanged. Using field data, we demonstrate that the proposed formulation can provide fast solutions to large-scale production optimization problems. The results in this paper suggest that the developed technique can be applied to improve production performance and operation efficiency with a minimal computational cost when compared to production optimization with full-scale reservoir simulation. It also offers the flexibility to adjust the problem formulation under various field conditions and is particularly useful when a full-scale reservoir model does not exist simulate the reservoir response for production optimization.
Fracking or Hydraulic Fracturing: How Media Shapes Public Perception and Regulatory Process
Authors: Schwartz Megan , Tormey Daniel R. , Middaugh Molly
Published: April 2015

Bans or moratoria on hydraulic fracturing are in place or being considered worldwide. In large part, these actions stem from relatively data-free media presentations of risks associated with hydraulic fractions. Our objective is to analyze the influence of media and public perceptions in shaping policy related to hydraulic fracturing and to use this evaluation to provide insight on balancing science with public perception in judging political risks and guiding public policy. By balancing science with public perception, good policy and a social license to operate result.

We conducted a literature review of the role of media in influencing public opinion on political issues and then focused the conclusions found in the literature onto the topic of hydraulic fracturing. We evaluated the influence of media, including movies, television, and traditional new outlets, as well as internet sources such as blogs, news aggregators, non-governmental organization (NGO) campaigns, and social media, and then compared these sources to the influence of published scientific literature in shaping public perception and political and regulatory oversight of hydraulic fracturing. The results of our analysis show that the large disconnect between scientific data and public opinion makes it difficult for elected officials and regulatory agencies to develop well-founded policies that regulate hydraulic fracturing in a manner that is accepted by both the public and industry. Based on these results, our study illustrates that public officials need to balance public opinion with data-rich scientific studies and analysis, and then weigh political risk when crafting legislation and public policy.
A New View of Produced Water: Resource, Not Waste
Authors: Middaugh M. , Tormey D. , Schwartz M.
Published: April 2015

Large volumes of saline water are produced during unconventional oil and gas development, and the water can rarely be reinjected into the same formation from which it was extracted. This water, known as produced water, can provide a valuable additional water source to local communities. For example, in Australia, South America, and the arid western United States, reusing produced water decreases demand on potable water supplies and aids in helping oil and gas operators achieve a social license to operate. However, produced water is currently regulated as a waste in almost all jurisdictions, limiting its beneficial reuse.

Our team has developed a reproducible framework to create comprehensive Produced Water Management Plans that provide operators with a large suite of options to beneficially reuse produced water. The framework consists of the following four steps: (1) Analyze the produced water source; (2) Understand the needs of local water users; (3) Compare the compatibility between the produced water quality and the water quality objectives of target end reuses; and (4) Determine the appropriate options for treatment if necessary. Once the plan is developed, the permitting and approval path is designed and implemented.

Examples of beneficial reuse options span from recycling for field use including well stimulation, to crop irrigation, industrial washwater, golf course irrigation, wildlife habitat support, and livestock watering. While the framework for developing management plans is widely applicable, the beneficial uses recommended within the plans are intensely site-specific due to local regulatory settings, reuse options available in the vicinity, and the chemical properties of the produced water. In California, the development of a Produced Water Management Plan led to a suite of reuse options including field water use, creek discharge to support critical wildlife habitat, and irrigation for local wineries. The latter two options required treatment. In Australia, the Produced Water Management Plan recommended livestock watering and industrial use with untreated water or irrigation for growth of fodder plants with treated water. These results demonstrate that beneficial reuse of produced water can gain regulatory approval and local acceptance. In times of water scarcity, wisely managing water resources becomes more important. As regulatory hurdles ease, there should be more opportunities for the beneficial reuse of produced water.
Enhanced Oil Recovery of Heavy Oil in Reservoirs With Bottom Aquifer
Authors: Delamaide Eric , Parra Moreno Wilson
Published: April 2015

Oil production in presence of a bottom aquifer is one of the most challenging issues in reservoir engineering. In most cases water coning happens very quickly and the influx of water restricts oil production and limits recovery. The problem is even more difficult when the oil is heavy because the viscosity contrast is large. In some cases horizontal wells may be used to improve the situation but when reservoirs are thin and the oil is viscous even horizontal wells are of limited use. This paper presents the challenges and potential solutions for Enhanced Oil Recovery in heavy oil reservoirs with bottom aquifer.

Existing literature is reviewed for field cases of EOR experience with bottom aquifer for chemical as well as thermal processes (SAGD, steam injection as well as In Situ Combustion).

In the case of chemical EOR the chemicals may be lost to the aquifer; for thermal recovery the bottom water can act as a heat sink and affect and steam oil ratio. Some in-situ combustion projects have been successful in such settings but in every case the outcome is the same: the economics of the project can be affected.

The paper contains some previously unpublished data of polymer injection in a heavy oil pool with some limited bottom aquifer; for the most part it is a review of the existing literature which may prove useful to practicing engineers who are faced with the issue of developing heavy oil resources in the presence of bottom aquifer.
Using Dynamic Simulations to Optimize the Start-Up of Horizontal Wells and Evaluate Plunger Lift Capability: Horn River Shale Gas Trajectory-Based Case Study
Authors: Nascimento C.M. , Becze A. , Virues C.J. , Wang A.
Published: April 2015

During the start-up of a horizontal multi-staged shale gas well, the fluid distribution within the well changes from a static segregated phase column to a flowing two-phase multiphase mixture. For the start-up to succeed, the well must overcome the hydrostatic head associated with this phase segregation in the vertical portion well as well as the liquid hold up in the lateral section of the well. The latter is heavily dependent on the well trajectory. The initial start-up procedure is critical to the life of the shale well since well clean up efficiency can be maximized at this stage. If the well is not properly cleaned up, the presence of liquid in the wellbore may increase which can make subsequent start-up attempts even more difficult.

As reservoir pressure declines with production, the gas flow rate also decreases with time. This eventually leads to liquid loading where the well can no longer effectively lift the associated liquids to surface. Liquid loading has a detrimental impact on production and a suitable deliquification or artificial lift method is required to sustain production and maximize recovery. In the planning phase of shale gas development, it is important to evaluate the artificial lift method that will be implemented to maximize the shale well's productive life.

It was studied three Horn River shale gas wells, each with different trajectories. A transient multiphase simulator is used to: 1) simulate the gas well liquid loading process in the three wells; 2) simulate gas well deliquification with plunger lift; 3) optimize the start-up procedure of the wells. These simulations provided valuable insight into the flow and pressure transients that characterize shale production. The results of this study provide guidelines for optimizing the start-up of horizontal shale wells and for designing the optimum shale well trajectory for plunger lift operations. This approach has not been presented before in literature and emphasizes the role of transient simulation in the planning phase of shale developments.
Fuzzy Decision Support Based on Exact Rule Matching for Liquid Lift Optimization
Authors: Rajati M.R. , Mendel J.M. , Popa A.S.
Published: April 2015

In this paper, we present a data driven methodology for designing a decision support system for controlling the choke setting in a Cyclic Steam Stimulation (CSS) system based on fuzzy logic. The goal of the fuzzy decision system is to find a choke setting that enhances the amount of liquid offload in different situations and therefore, the production of oil. Historical data are used to establish descriptive rules that represent the production of each well in terms of four influential variables (recommended by experts) and the decision variable (choke setting) in the form of fuzzy IF-THEN rules. Those influential variables and the choke setting constitute the antecedents of the descriptive rules, while the production is in the consequent part of each rule. Each of the variables is described by three fuzzy sets (e.g., Low, Medium, High). These fuzzy sets are established using fuzzy clustering techniques.

The goal of the decision system is to make the production High by changing the choke. Since abrupt changes in the choke setting are not desirable, this goal must be achieved by first making the production Medium and then High.

In order to realize which conditions yield Low, Medium, or High production, the descriptive rules are grouped according to their consequents. Then, the rules in the group “Low production” are compared with those in the group “Medium production” to find the pairs of rules (each of those two rules is from one of the groups) for which all the antecedents are exactly the same excepting the antecedent that describes the choke setting. This suggests that only changing the choke will result in driving the output of the system (i.e. the production) towards Medium. This calls for establishing a decision rule whose antecedents are the same as those of the compared pair of rules, while whose consequent is a fuzzy set that describes the change in the choke setting, derived by the fuzzy subtraction of the two fuzzy sets describing the choke in each rule in the compared rule pair. Subtraction of fuzzy sets involves fuzzy arithmetic methods such as the α-cut decomposition method and the Extension Principle. The rule comparison procedure is repeated for rules in the groups “Medium production” and “High production” as well. The collection of the decision rules that are synthesized based on comparing descriptive rules comprises the fuzzy decision system for liquid lift optimization.

The fuzzy decision system can be implemented using Programmable Logic Controllers that are common in the petroleum industry. In this paper, we present the decisions that the system would make in a real situation, and compare them to the decisions made during a pilot test.
Leading Safety, Health, and Environmental Indicators in Hydraulic Fracturing
Authors: Jabbari Nima , Ashayeri Cyrus , Meshkati Najmedin
Published: April 2015

Increasing number of hydraulic fracturing operations necessitates paying more attention to the safety and environmental considerations of this technology. In-depth understanding of the complex nature and root-causes of incidents related to the hydraulic fracturing operation is a prerequisite for any proactive risk mitigation strategy. Many of the safety and environmental incidents during the development of shale resources are widely regarded by public as results of hydraulic fracturing operation. Differentiation among multiple steps of developing oil and gas resources allows an independent root cause analysis. In this approach incidents that are not directly caused by underground injection of fracturing fluid can be highlighted. These incidents can be treated in the same manner as common incidents in conventional production. In this research the hydraulic fracturing operation is broken down into its components and potential risks are investigated. Also, leading safety and environmental indicators for this industry are defined and case-studies are investigated to find the connections between the incidents and the proposed indicators.
Application of Micro-Proppant to Enhance Well Production in Unconventional Reservoirs: Laboratory and Field Results
Authors: Dahl Jeff , Nguyen Philip , Dusterhoft Ron , Calvin James , Siddiqui Shameem
Published: April 2015

As more wells are drilled and completed in tight, brittle formations, operators rely more on small-sized proppants to help ensure the created complex fractures are propped, and to maintain conductive flow paths for production. Most microfractures generated in the far-field away from the primary fracture branches are believed to return to a closed state soon after the release of hydraulic pressure, unless propping agent has been successfully placed inside such fractures. This paper presents the results of laboratory study, numerical modeling, and field trials, to demonstrate and quantify the effectiveness of a new treatment method for enhancing conductivity of microfractures and primary fractures formed in tight formations, thus helping improve well production.

The approach involves using a micro-proppant (MP) and an aqueous-based surface modification agent (ASMA) as part of the pad fluid stage to treat fracture faces of microfractures and leakoff induced fractures before placement of larger-sized proppant into the primary fractures. This coating causes the proppant particulates to adhere to the created fracture faces by forming partial monolayer, thus mitigating settling and enhancing vertical distribution in the fractures. During experimental testing, various shale core samples were split along the core length to create artificial fracture faces. These fracture faces were then exposed to MP or proppant slurry treated with an ASMA, and were then reassembled for core flow testing under closure stress. An effective permeability comparison of the fractured cores, with and without ASMA treated MP or proppant, demonstrated a dramatic effective permeability increase in fractures of the treated cores.

Field treatments involved injection of pad fluid containing a low concentration of MP, with and without treating with ASMA in offset wells, to treat the microfractures formed in the far-field regions. Proppant slurry of larger size particulates (100-mesh and larger) then followed to prop the primary fractures and their branches. Production from wells treated with MP have shown to provide significant improvement in terms of liquids production compared to the production of control wells. Reservoir simulation performed in this complex retrograde condensate reservoir supports this result, with sensitivity testing showing that increasing the connected fracture area enables the production of more hydrocarbon liquids at higher sustained production rates.
Data Driven Approach to Failure Prediction for Electrical Submersible Pump Systems
Authors: Guo Dong , Raghavendra Cauligi S. , Yao Ke-Thia , Harding Mark , Anvar Amir , Patel Anil
Published: April 2015

This paper presents a data driven approach for failure prediction for Electrical Submersible Pumps (ESP). ESP system is well known as an effective artificial lift method which has been applied to about 20 percent of almost one million wells worldwide. Well failures lead to production loss and generally the repair cost for an ESP is usually much higher than those of other artificial lift systems, thus predicting ESP failures before they occur will be valuable. We apply advanced machine learning techniques for predicting ESP failures using electrical and frequency data from the field. Data from real-world assets using ESP systems is analyzed to learn examples of normal well and failure conditions. A generalized Support Vector Machine (SVM) trained with a set of selected features is developed and this approach is tested on real world data. Our results show that this approach works well based on feedback from subject matter experts on the results.
Modeling Asphaltene Deposition in the Wellbore During Gas Lift Process
Authors: Abouie Ali , Shirdel Mahdy , Darabi Hamed , Sepehrnoori Kamy
Published: April 2015

Asphaltene deposition during oil production may partially or totally plug the wellbore, and results in significant reduction in well production and frequent asphaltene remediation jobs. It is well-known that injection of lighter hydrocarbons into an asphaltic oil (e.g. during gas lift) may decrease the stability of asphaltene particles in the solution and increase the risk of asphaltene precipitation and deposition. Although a great deal of research has investigated the effect of gas injection on the phase behavior and mechanism of asphaltene deposition in the wellbore, we lack a comprehensive dynamic model that can track the behavior of asphaltene during gas lift process. Therefore, a comprehensive model is required for evaluating the risk of gas lift on asphaltene deposition in production wells.

This paper presents a comprehensive thermal compositional wellbore model with the capability to model asphaltene phase behavior during gas lift and determine the effect of the injected gas on asphaltene deposition in the wellbore. In the developed wellbore simulator, various numerical approaches are used to model multiphase flow in the wellbore. An equation of state was used to calculate the thermodynamic equilibrium conditions of the phases. In addition, several deposition mechanisms were incorporated to study the transportation, entrainment, and deposition of solid particles in the wellbore.

Various case studies investigated the effect of gas lift on asphaltene deposition. To predict where and when the most severe damage would occur in the wellbore, we used field data of a Middle East crude oil and an injection gas. The results showed that the injection of light gas composition can negatively affect the production facilities by intensifying asphaltene precipitation in the well, which eventually results in significant reduction in the wellbore production. We believe that this comprehensive thermal compositional wellbore model can facilitate the design of work-over operation plans for asphaltic wells operating under gas lift.
Using Wireline Standoffs (WLSOs) To Mitigate Cable Sticking
Authors: Wheater G. , Paterson Lee , Kidd Ben , MacLeod Rob , Huyton Stuart , Miller Luke , Hyson Lee , Sauder Matt , Morris Bill , Hall John
Published: April 2015

The recent development of wireline standoffs (WLSOs) has effectively eliminated cable sticking during deepwater logging operations, offering a viable alternative to pipe-conveyed logging, and saving considerable rig time and risk in the process. On eight high overbalance wells in the Gulf of Mexico, multiple arrays of wireline standoffs (WLSOs) have been successfully deployed to facilitate deep formation sampling without any incidence of cable sticking. This success should be viewed in the context of the fact that the cable force modeling for WLSO deployment indicated that several fishing operations were averted.

The oil and gas industry has been using standoffs for years in order to prevent sticking of everything from logging tools to casing. Applying standoff technology to logging cable was a natural progression, although there were many technical challenges that needed to be overcome in order to make the effective use of WLSOs a reality. To begin, the wireline standoffs could not be allowed to damage the logging cable. Yet, these standoffs had to provide a grip sufficient to avoid slippage under high tensions. In addition, the WLSOs needed to be capable of both maximum cable lift and minimal formation contact, while allowing a 3-3/8” fishing grapple to smoothly pass over them. Finally, WLSO modeling had to be able to identify their optimal placement on the cable, taking into account such factors as logging objectives, wellbore trajectory, and applied cable forces (including cable sag between WLSOs in deviated holes).

This paper discusses the origins of WLSO design, job planning, and operating procedures. Recommendations for future research into the issue of cable sticking are also included.
Automatic 3D Industrial Point Cloud Classification and Modeling
Authors: Pang Guan , Qiu Rongqi , Huang Jing , You Suya , Neumann Ulrich
Published: April 2015

3D classification and modeling of point clouds is an important but time-consuming process, with many applications in petroleum engineering and other applications, inspiring extensive research in automatic methods. Prior efforts focus on primitive geometry, street structures or indoor objects, but industrial data has rarely been pursued. Industrial sites are often captured by laser scanners, producing 3D point clouds of visible surfaces. Creating a higher level model from such point clouds now requires extensive manual labeling and fitting of surfaces and their connections. Computer-aided editing systems and automatic methods exist, but with limited capabilities. Existing methods for industrial point cloud modeling are not able to effectively process an industrial scene containing primitive shapes, general objects and instrumentations, as well as the connectivity between them.

Our work presents a method which automatically generates a 3D classified model from 3D point cloud data. An industrial point cloud is treated as a collection of pipes, planes and general objects, and we thus divide the modeling problem into three sub-problems: pipe modeling, plane classification, and object recognition. Two primitive extraction processes detect cylinder or planar geometry in the scene, while general objects modeling employs modeling-by-recognition, which detects clusters of 3D points in a scan that match 3D models of objects stored in a prebuilt object library. The results of all three components, including extracted primitives and recognized objects, are integrated to obtain the complete 3D model.

Experiments with several point cloud datasets demonstrate that the presented method automatically produces classified models of large and complex industrial scenes, with a quality that outperforms leading commercial modeling software and is comparable to professional hand-made models. Pipes, planes and different types of objects are individually detected and classified. The result display is freely switchable between mesh model for efficiency and point cloud for accuracy, not achievable in simple surface fitting methods.
Case Study of Managed Pressure Tripping Operation through Abnormal Formations in West Canadian Sedimentary Basin
Authors: Mammadov Elvin , Kinik Koray , Ameen Rostami Sayamik , Sephton Sheldon
Published: April 2015

The deep basin of British Columbia, Canada contains the Montney and Doig plays, which are categorized as tight gas sands. Both are considered major unconventional gas plays containing vast quantities of gas in the west and oil in the coarser eastern facies. The formations have high initial formation pressure which promotes production, however during drilling causing drilling challenges. It is especially difficult when drilling through the abnormally pressured Doig transit zone. This is further complicated when a trip is required for the bit as the swabbing effect, if not properly managed, can easily escalade into a well control event.

Due to the overpressured and geologically fractured formations, it is very difficult to trip the drill string out of the well safely without using specialized techniques. MPT is one such method that can be utilized in these scenarios. Managed Pressure Tripping allows the driller to control bottomhole pressure (BHP) in different types of abnormally pressured zones, and simultaneously eliminating the swabbing effects by holding surface back pressure (SBP) with the managed pressure drilling (MPD) system. Applying MPT techniques on subnormal and overpressured formations results in safe and cost effective drilling operations.

This paper presents a case study where advanced Managed Pressure Tripping (MPT) technology was successfully applied in the Altares field in British Columbia, Canada, to mitigate well control challenges associated with swabbing. The study elaborates on recommended operational procedures, engineering calculations, equipment set up and process flow diagrams along with the analyzed graphical data.
ALWORKS – An Artificial Lift Surveillance Tool
Authors: Burleson Gayle L. , Redden J. D.
Published: April 2015

More effective use of computing tools for production surveillance by operations and engineering personnel is critical to increases in profitability. Exxon's ALWORKS (Artificial Lift Workstation) is a software package that provides easy access to electronically stored data and provides that data to various surveillance, analysis and design applications with minimal user effort. The software has been field tested and significant increases in productivity by operations personnel have been observed, which will lead to increases in profitability.
Young, Old, and Weathered Carbon—Part 2: Using Radiocarbon and Stable Isotopes to Identify Terrestrial Carbon Support of the Food Web in an Alkaline, Humic Lake
Authors: Keaveney Evelyn M , Reimer Paula J , Foy Robert H
Published: April 2015

Carbon (C) and nitrogen (N) stable isotope analysis (SIA) has been used to identify the terrestrial subsidy of freshwater food webs. However, SIA fails to differentiate between the contributions of old and recently fixed terrestrial C and consequently cannot fully determine the source, age, and biochemical quality of terrestrial carbon. Natural abundance radiocarbon (Δ14C) was used to examine the age and origin of carbon in Lower Lough Erne, Northern Ireland.14C and stable isotope values were obtained from invertebrate, algae, and fish samples, and the results indicate that terrestrial organic C is evident at all trophic levels. High winter δ15N values in calanoid zooplankton (δ15N = 24‰) relative to phytoplankton and particulate organic matter (δ15N = 6‰ and 12‰, respectively) may reflect several microbial trophic levels between terrestrial C and calanoid invertebrates. Winter and summer calanoid Δ14C values show a seasonal switch between autochthonous and terrestrial carbon sources. Fish Δ14C values indicate terrestrial support at the highest trophic levels in littoral and pelagic food webs.14C therefore is useful in attributing the source of carbon in freshwater in addition to tracing the pathway of terrestrial carbon through the food web.
Robot Skill Learning: From Reinforcement Learning to Evolution Strategies
Authors: Stulp Freek , Sigaud Olivier
Published: April 2015

Policy improvement methods seek to optimize the parameters of a policy with respect to a utility function. Owing to current trends involving searching in parameter space (rather than action space) and using reward-weighted averaging (rather than gradient estimation), reinforcement learning algorithms for policy improvement, e.g. PoWER and PI
Towards Hybrid EEG-EMG-Based Control Approaches to be Used in Bio-robotics Applications: Current Status, Challenges and Future Directions
Authors: Lalitharatne Thilina Dulantha , Teramoto Kenbu , Hayashi Yoshiaki , Kiguchi Kazuo
Published: April 2015

In the last few decades, bio-robotics applications such as exoskeletons, prosthetics and robotic wheelchairs have progressed from machines in science fiction to nearly commercialized products. Though there are still several challenges associated with electromyography (EMG) signals, the advances in use of EMG signals for controlling such bio-robotics applications have been enormous. Similarly, recent trends and attempts in developing electroencephalography- (EEG) based control methods have shown the potential of this area in the modern bio-robotics field. However, the EEG-based control methods are also yet to be perfected. A new approach of combining both these control methods, which take the advantages, and diminish the disadvantages, of each system might therefore be a promising approach. In this paper, we review hybrid fusion of EMG- and EEG-based control approaches in the bio-robotics field which have been attempted or developed to date. We provide a design overview of the method and consider the main features and merits/disadvantagages for the approaches that have been analyzed. We also discuss the current challenges regarding these hybrid EEG-EMG control approaches and propose some potential future directions.
Profile Following for Inspection of Underwater Structures
Authors: Galceran Enric , Palomeras Narcís , Carreras Marc
Published: April 2015

We present a seabed profile estimation and following method for close proximity inspection of 3D underwater structures using autonomous underwater vehicles (AUVs). The presented method is used to determine a path allowing the AUV to pass its sensors over all points of the target structure, which is known as coverage path planning. Our profile following method goes beyond traditional seabed following at a safe altitude and exploits hovering capabilities of recent AUV developments. A range sonar is used to incrementally construct a local probabilistic map representation of the environment and estimates of the local profile are obtained via linear regression. Two behavior-based controllers use these estimates to perform horizontal and vertical profile following. We build upon these tools to address coverage path planning for 3D underwater structures using a (potentially inaccurate) prior map and following cross-section profiles of the target structure. The feasibility of the proposed method is demonstrated using the GIRONA 500 AUV both in simulation using synthetic and real-world bathymetric data and in pool trials.
Enhancement of the Communication Effectiveness of Interactive Robots for Autism Therapy by Using Touch and Colour Feedback
Authors: Lee Jaeryoung , Takehashi Hiroki , Nagai Chikara , Obinata Goro , Stefanov Dimitar
Published: April 2015

Previous studies in the field of robot assisted therapy demonstrated that robots engage autistic children’s attention in a better way. Therefore, the interactive robots appear to be a promising approach for improving the social interaction and communication skills of autistic children. However, most of the existing interactive robots use a very small number of communication variableswhich narrow their effectiveness to a few aspects of autistic childrens’ social communication behaviour. In the present work, we explore the effects of touching and colours on the communication effectiveness between a robot and an autistic child and their potential for further adjustability of the robot to child’s behaviour. Firstly, we investigated touching patterns of autistic and non-autistic children in three different situations and validated their responses by comparison of touching forces. Results showed that patterns of touching by non-autistic children have certain consistency, while reaction patterns in autistic children vary from person to person. Secondly, we studied the effect of colour feedback in autism therapy with the robot. Results showed that participants achieved better completion rate when colour feedback was provided. The results could support the design of more effective therapeutic robots for children with autism.
A social learning formalism for learners trying to figure out what a teacher wants them to do
Authors: Cederborg Thomas , Oudeyer Pierre-Yves
Published: April 2015

This article presents a theoretical foundation for approaching the problem of how a learner can infer what a teacher wants it to do through strongly ambiguous interaction or observation. The article groups the interpretation of a broad range of information sources under the same theoretical framework. A teacher’s motion demonstration, eye gaze during a reproduction attempt, pushes of “good"/“bad" buttons and speech comment are all treated as specific instances of the same general class of information sources. These sources all provide (partially and ambiguously) information about what the teacher wants the learner to do, and all need to be interpreted concurrently. We introduce a formalism to address this challenge, which allows us to consider various strands of previous research as different related facets of a single generalized problem. In turn, this allows us to identify important new avenues for research. To sketch these new directions, several learning setups are introduced, and algorithmic structures are introduced to illustrate some of the practical problems that must be overcome.