bluuebunny/crossref_metadata_2025 huggingface dataset:
Case Studies: Optimizing BHA Performance by Leveraging Data and Advanced Modeling
Authors: Shahri Mojtaba , James Moisan , Vasicek Alan , De Napoli Roy , White Matthew , Behounek Michael , D'Angelo John , Ashok Pradeep , van Oort Eric
Published: September 2019

Given the intensity of drilling operations in the North American unconventional reservoirs and the quality and amount of data gathered during a drilling operation, leveraging those data along with advanced modeling techniques for optimization purposes is becoming more feasible. In this study, historical data and advanced physical modeling are utilized to better understand and optimize the bottom-hole assembly (BHA) performance in drilling operations. A comprehensive data set is gathered for more than 300 BHA runs in the span of three years. This extensive data set enables thorough examination of the variation in the operational parameters and its effect on the drilling performance.

Different indices are used to determine and evaluate drilling performance, such as rate of penetration (ROP). Excessive tortuosity in a well can have many detrimental effects while drilling such as excessive and erratic torque and drag, poor hole cleaning (cuttings removal), low ROP, along with problematic casing and/or liner runs and associated cementing procedures. In this paper, a tortuosity index (TI) is used to quantify the drilled well quality and correlate it to ultimate drilling performance. In the next step, patterns are extracted and used along with physical modeling for optimizing drilling performance before the well is drilled.

The corresponding tortuosity index can be used as a proxy for the well path smoothness and may be used for quantifying parameters affecting drilling performance. According to historical drilling performance data, there appears to be a strong relationship between wellbore tortuosity and ROP. If drilling operating parameters (e.g., BHA configuration, directional company's performance, target formations, bit specification, mud types, etc.) can be related to the TI based on historical data, such parameters can be modified for optimizing the performance before the well is drilled.

By investigating the historical data, different trends have been extracted. In addition, different models can be built to predict drilling performance (e.g., TI) prior to drilling and according to new well design specifications. Based on data from more than 300 BHA runs and using advanced physical modeling, the most strongly correlated parameters to drilling performance have been determined and shown using different case studies. Such a historical database along with modeling techniques are used to predict well quality and drilling performance during the design phase. Using this method, well design specifications can then be optimized to enhance drilling performance and reduce the cost.
High Molecular Weight Organic Scale; A Sticky Journey in Finding the Solution
Authors: Sidek Sulaiman , M. Hatta Siti Aishah , Goh Hui Lian Kellen , Tan Kok Liang , M. Yusuf M. Hafizi , Tang Ye Lin Catherine , Mawardi M. Hizbullah , Hamzah Haziqah , Masngot Ainul Azuan , M. Jeffry Suzanna Juyanty , Riyanto Latief , Ahmat Kamis Azman
Published: September 2019

Flow assurance has been a big focus of oil and gas operation in ensuring the delivery of the targeted production. A few fields located offshore Malaysia have been experiencing solid deposition inside tubing and stable micro-emulsion from early stage of their life. Oil production from Field W begin in January 2003, unfortunately the wells produced viscous stable emulsion which caused the production decline significantly. Multiple analyses and efforts, including chemical and mechanical treatments, conducted over the years with minimal success. The damaging mechanism was determined to be caused by rare organic deposit that have caused a significant pressure drop in the tubing, which consequently restrict oil production and tested to only disperse at above 90°C. It was suspected that the organic deposit was a naturally occurring component of the crude oil itself, separating from the bulk of the crude as a consequence of the fluids movement towards the wellbore and the consequent drop in fluid pressure.

This paper focuses on the step-by-step workflow developed to identify the solid deposition, laboratory testing, treatments conducted and the result of different chemical treatments in Field W. The ultimate effort was by developing an advanced eco-friendly nano-fluid to remediate the rare issue of High Molecular Weight Organic Deposit (HMWOD) in the fields. The nano-fluid pilot treatment was conducted in 2014 and successfully rejuvenate the well with total of 20,000bbl incremental oil volume. Early 2018, subsequent treatments were conducted that contributed substantial improvement to the field production and at lower total treatment cost. This advanced chemical using nano-fluid technology concept is deemed feasible and will be further replicated in other fields.

This paper is highly beneficial to Operators, Petroleum and Flow Assurance Engineers experiencing flow assurance issue on organic scale such as microcrystalline wax, high molecular weight wax and stable emulsion in the crude production. This paper also promotes the use of nano-fluid technology as part of the solution to flow assurance issue in Oil and Gas industry.
Reservoir Flow Allocation and Quantification Using Spectral Acoustic Data and Temperature Logs: Case Studies in Highly Deviated and Horizontal Wells Equipped with Slotted Liners and Sandscreens
Authors: Alimohammadi Hamzeh , Aslanyan Irina , Minakhmetova Roza , Skutin Vasily , Martin Julian
Published: September 2019

In highly deviated and horizontal wells, focusing on inside wellbore data (flowmeter, hold-up, density, etc.) may not be enough to understand in full the well and particulary reservoir behavior, as most of the time downhole logging tools lack the capacity to reveal reservoir/well interaction, mainly in those cases where flows could occur outside the wellbore (e.g. slotted liner or sandscreen). The objective of this paper is to provide a unique solution following which a thorough understanding of flow inside the wellbore and up to five meters into the reservoir can be obtained by temperature and spectral acoustic logs.

Fluid flows in wells completed with slotted liners or sandscreens, especially those in deviated and horizontal wells, can occur either inside or outside the liner and/or casing. The conventional production logging technique in this type of completion is usually based on results generated by a mechanical flowmeter which measures flow only inside the wellbore but fails to depict flows and entry points behind tubing/casing; for example, when there is flow through cement channels or flow inside the annular section of the wells completed with a slotted liner.

Mechanical spinners have other limitations; 1) they cannot pick up small rates in low potential wells, 2) they can give false response of apparent down flow (heavy-phase recirculation) in deviated wells with 2- and 3-phase flow, 3) they are prone to harsh wellbore conditions, particulary in open-hole completions. The Total Flow analisys (borehole and reservoir flow) uses Chorus spectral acoustic and Cascade temperature logging suite is an innovative addition to conventional single and multi-array PLT tools which are designed to address the above issues. This is done by a combination of hardware and modelling solutions which can be run in highly deviated and horizontal wells with a multi-phase flow and is able to pick up small flows behind multiple barriers.

This paper presents the Total Flow results of spectral acoustics and temperature logging suite run in two horizontal wells equipped with sandscreens, and two highly deviated wells, all completed with slotted liners. These are the most difficult cases where conventional production logging tools usually fail to give vigorous results on fluid entry points as wells as the flow rate at each entry point, whereas spectral acoustic and temperature logs combination can provide detailed results on both entry points and quantity of each phase. The paper also compares the results of production logging and spectral acoustics/temperature logs in three wells to emphasize how using an inappropriate tool for a certain condition could give a wrong result which is far from the actual downhole situation.
A History of Operations Research Optimization in the Petroleum Industry
Authors: DiCarlo Jennifer , Eustes Alfred , Steeger Gregory
Published: September 2019

In the petroleum industry, references to a new science called Operations Research appeared in the literature in the late 1950s; however, over the last 60 years, use of Operations Research optimization techniques in the petroleum industry has been sporadic, resulting in vast untapped optimization opportunities. Some subsets of the petroleum industry have successfully used Operations Research optimization techniques for specific applications; however, when these techniques were not used by the industry, the stated reasons involved difficulty dealing with non-linearities and stochastic elements, insufficient computational power to solve realistic models, and the necessity for specialized knowledge of Operations Research optimization software and solvers. In this paper we provide a history of the use of Operations Research optimization methods in the petroleum industry by presenting a comprehensive review of papers that use these techniques. We focus on linear, non-linear, integer, and mixed-integer optimization methods and the evolution of these models in the petroleum industry over time. Finally, we provide examples of sub-optimal optimization schemes and explore reasons for the lack of Operations Research optimization use in the petroleum industry.
Mitigation of Paraffinic Wax Deposition and the Effect of Brine
Authors: Kar Taniya , Firoozabadi Abbas
Published: September 2019

Wax deposition in wells from shale oil production is a major challenge. Crystal modifiers and dispersants may mitigate wax deposition via steric hindrance and wettability alteration, respectively. Interaction of reservoir brine coproduced with oil and the chemicals may increase mitigation efficiency. This study investigates quantitative effect of brine on inhibitor performance, at three different flow rates, representing different field conditions.

Two dispersants and two crystal modifiers at low concentrations (500-1000 ppm) are selected among eight chemicals after screening. In our work, pressure drop in flowlines is a measure of mitigation efficiency. Three light crude oils are investigated; they are from shale formations which have high wax content. Brine effect on chemical performance is investigated from high flow rate to low rates. To select chemicals and provide a guide for flow experiments, we include optical microscopy with polarized light, rheology, and particle size measurements as part of the study.

Crystal modifiers are observed to delay pressure build up from deposition significantly compared to dispersants. For dispersants, the effect of brine is found to improve efficiency. At the intermediate flow rate, brine is found to increase efficiency of two dispersants, AO4 and PARA, by 70% and 21%, respectively, in terms of total fluid transported before blockage. For crystal modifiers, there is practically no increase in flow throughput by brine. Dispersant and brine have a synergistic effect, leading to decrease in adsorption of wax crystals on the surface of pipeline. Crystal modifiers do not have an appreciable effect on surface wettability in the presence of brine and no significant improvement is observed in inhibitor efficiency. The observation is the same for all four crystal modifiers in the screening tests at three different flow rates in the flow experiments. The eight chemicals used in this work were provided from different companies. The basis of their selection was on reduction of viscosity in vials from the addition of small amount of chemicals. We find that viscosity reduction alone is not a measure of effectiveness of chemicals. All the chemicals supplied by various companies reduce viscosity of the shale oil sample at the conditions of wax formation. However, deposition in dynamic flow tests do not relate to bulk viscosity reduction.

Our investigation includes a comprehensive set of particle size and flow measurements of low dosage crystal modifiers and dispersants in wax mitigation over a range of flow rates. There is a significant synergistic action of dispersants and brine. Chemical inhibitor performance is a strong function of flow rate and metal surface.
Enhanced Problem Solving Approach to Tackle Repetitive System Failures
Authors: Mukhamediyeva Assel , Sutcliffe Francesco Gigli , Kaitupov Sezim
Published: September 2019

The paper describes an innovative approach to performance improvement using Causal Learning (CL), a method based on the general observation that a business performance is largely the outcome of the organization, processes and procedures, ways of working, constraints and norms – the systems that the business applies to itself. These system causes are often remote from physical causes of equipment failures and as such remain hidden until revealed by appropriate analysis. The objective of CL is discovering these system causes that ultimately lead to an undesired outcome or event. CL helps us "learn" the performance system, develop insights from these discoveries and recognize the specific aspects of a system that require change to shift business performance.

The Company adopted this approach to improve problem solving and root cause analysis of machinery failures. The initial decision to apply CL followed several outages of power generation systems that continued to occur after previous analyses of similar events in the past.

An Enhanced Problem Solving Team (EPST) was established and trained to apply Causal Learning principles to reveal the underlying system causes of these outages. In the time since that first analysis the tools and techniques of CL have been applied to other undesired or unexpected business outcomes including HSE and project work with little or no direct technical content.

CL reveals the contribution of well-intended human behaviours behind unwanted outcomes (e.g. hardware failures), and importantly the underlying system causes of these human behaviours. This is predicated on the basis that people do their best to achieve the goals they believe they need to achieve. When it is revealed why those goal were important and why the actions taken were "their best" with the time, tools, processes available to the individual at that time at that place the systems causes can be properly understood. These findings often surprise the organization, particularly when it is made visible to Leaders at all levels how they created, or are responsible for, the systems that influenced those human behaviours.
A Completion Technology Milestone: A HPHT Ultra-High Expansion Openhole Packer for Multi-Stage Completions
Authors: Deng Guijun , Kendall Alexander , Cook Christopher , Wakefield John , Maenza Frank , Tom Andy , Knebel Mark
Published: September 2019

This paper is a continuation of a previous work, SPE191734 (Deng, 2018) which focused on integrating additive manufacturing into completions technology to develop a packer of ultra-high expansion with a 10,000 psi pressure rating at 300°F. This paper presents the work that further extends the packer's capabilities to withstand pressures of 15,000 psi and temperatures up to 350°F while maintaining high expansion, tested to ISO 14310 V3 pressure acceptance criteria.

Three factors primarily contributed to its successful qualification. First, new backup technology eliminated traditional design limitations imposed by conventional manufacturing and enabled us to design and print a backup system with ultra-expansion capacity and superior conformability. Second, an internally developed polymer that exhibits great elongation and extrusion resistance played a key role in holding the 15,000 psi pressure reversals at 350F in the ultra-expansion states. Finally, a state-of-the-art design process seamlessly integrated design, material characterization, design optimization, and test validation, enabling rapid failure diagnosis and design iterations to ensure rigorous customer requirements were satisfied. This integrated process reduces development costs and shortens time to market.

An ultra-high expansion openhole HPHT packer was developed as a result of advances in Additive Manufacturing technology, polymeric materials, and a holistic design process. Physical test validation demonstrated:

15,000 psi pressure reversal and 15 minute hold at 350°F. Displacement of 0.5 in and 15,000 pressure reversal at 350°F. Elastomer element system remained in good visual condition in post-test inspection.

This is the industry's first commercial completion packer with an Additive Manufactured element containment system. It is also the industry's first ultra-expansion packer to demonstrate HPHT capability.
Evaluation of Air Injection into Mature SAGD Chambers as a Follow Up/Wind-Down Strategy, Using a Novel Large Scale 3-D Physical Model
Authors: Aminfar Ehsan , Sequera-Dalton Belenitza , Mehta Sudarshan Raj , Moore Gordon , Ursenbach Matthew
Published: September 2019

The injection of air into mature steam chambers is a promising technology to reduce the steam-to-oil-ratios (SOR) in late stages of the Steam-Assisted-Gravity-Drainage (SAGD) recovery process in Athabasca oil sand reservoirs in Alberta, Canada. Air injection allows sustaining steam chamber pressures with reduced steam injection rates. The steam capacity that becomes available due to the replacement of steam with air in mature well-pairs or pads could serve new pads optimizing steam utilization and decreasing the overall environmental footprint of the project. A novel large scale three-dimensional (3-D) physical model was designed to evaluate the prospect of the "hybrid" air and steam injection technology in a SAGD configuration utilizing up to three well-pairs. This paper discusses the 3-D model design, commissioning, experimental procedure and main results of the first tests.

For each test, the 3-D model was packed with a low oil saturation core or lean zone, representing the reservoir portion swept by steam, and a high oil saturation core or rich zone representing the un-drained zone between two coalesced steam chambers. These zones were made with preserved native "lean" and "rich" cores from Athabasca reservoirs. Once the model was packed, it was placed inside a pressure jacket where it was pressurized to reservoir pressure. Steam was injected into the model to develop a representative steam chamber in the lean zone. Once steam conditions were attained in the lean zone, steam injection was switched to air injection. Temperatures distributed in the 3-D model as well as injection and production pressures and produced gas compositions were monitored constantly and recorded during the test. Produced liquid samples were regularly captured and stored for subsequent analysis. Post-processing analyses of produced fluids and residual extracted core material allowed for determination of clean-burned zones, material balance, upgrading of the produced bitumen samples and efficiency of the process.

High peak temperatures, gas compositions, clean-burned sand in post-test cores and significant oil production indicate the development of a high temperature combustion front in the 3-D experiments. The test results confirm the injection of air into mature SAGD chambers is a very promising method not only to reduce the cumulative steam-to-oil-ratios (CSOR) and to sustain the steam chamber pressures but also to increase oil production in SAGD late life.
Drilling Optimization Using Model-Based Design and Stratigraphic Zonation: Successful Application in Brazilian Deep Water Pre-Salt Carbonate Reservoir
Authors: Aguiar Romulo , Tocantins João Pedro , Marquinez Victor , Baines Victoria , Barreto Diogo , Gozzi Danilo , França Rafael
Published: September 2019

After findings were made in the pre-salt province that represented a major discovery for the oil industry, drilling activity in Brazil has been focused primarily on economically viable ways to develop these reserves. The pre-salt cluster is a geological formation that consists of organic microbial carbonates and other sediments. The reservoir poses innumerous drilling challenges, including hard silicate nodules and low-porosity layers, which make the formation strength extremely high. Also, the heterogeneity level of such carbonates (within centimeters) imposes extra challenges, especially on drilling shock & vibration, with low rates-of-penetration (ROP), raising pre-salt well construction costs. To offer a technical solution, the service provider applied an innovative approach based on two pillars: a model-based design approach, leading to two drill bit designs with improved cutting structure resistance, with dynamic stability, delivering the entire section in one bit run with higher ROP. Along with the technology, a new workflow called "stratigraphic zonation for drilling" was implemented. This paper reviews the work covering this new stratigraphic zonation workflow, the development of this virtual drilling scenario and some field results with lessons learned and way forward.
The Stakes of Foam Stability in Foam-Based EOR Processes Designed for Naturally-Fractured Reservoirs
Authors: Pedel Nicolas , Delbos Aline , Batot Guillaume , Chevallier Eloise
Published: September 2019

Objective/Scope

Enhanced-Oil-Recovery processes for Naturally-Fractured Reservoirs usually require fluids mobility control in the fractures, which can be ensured by foam-based processes. The latters have to demonstrate stability over very long distance as their efficiency rely on the pressure increase in the fractures network. Despite their potential, the ability of foams to propagate and regenerate in fractures, but also the most adapted design of foaming-surfactant formulations, are poorly documented. These issues are addressed in this experimental paper.

The propagation of foams over long-distance fractures (from 100 to 1000 meters) is modelled at the lab-scale by a flow of pre-formed foams in long vertical and horizontal tubings (from 0.01m to 10 meters). The visualization of the flowing foam and the measurement of pressure allow identifying the physical phenomena which account for foam evolution in horizontal and vertical configurations. Comparison of performances is also conducted for several formulations differing by their foam performances in sandpack and by their wettability alteration properties.

A preliminary test shows that co-injection of gas and liquid in a representative oil-wet fracture generates very poor foams, unlike classical porous media (sandpacks, rock core samples). This poor rejuvenation of foam evidences that foam flow in fracture strongly differs from observations in porous matrix and highlights the need for long-term foam stability. In long tubings, characterization of different formulations first shows that the most efficient foams do not correspond to the best formulations identified for porous media. Criteria to optimize a foam formulation for fracture network seem specific. Second, the evolution of flowing foams highly differs from static foams and highlights the difference of performances brought by the flow. The local foam flow structure is different from one formulation to another. These results suggest that the ability to create a high pressure gradient depends on wettability properties of formulation, due the strong interaction of foam lamellae with walls along the flow.

To ensure an efficient foam-based process in a fractured reservoir, long-term stability is crucial yet not predicted by classical criteria based on porous media experiments. Besides, the best foaming-surfactant formulation for fractured systems corresponds to new criteria, likely related to wettability instead of apparent viscosity. This work has important implications on the design of foam injections in naturally fractured reservoirs regarding the calculation of liquid volumes, injection strategy to ensure foam propagation over long-distance.
Laboratory Development to Successful Field Application of Unconventional Non-Beaded Micromaterial for Making Lower Permeability Lighter and Stronger Cements
Authors: Pernites Roderick , Brady Jason , Padilla Felipe , Clark Jordan , Ramos Gladyss , Callahan Jaron , Garzon Ricardo , Sama Raymond , Embrey Mark , Fu Diankui , Johnson David , Richey Nicolas
Published: September 2019

Increasing horizontals, narrowing annular gaps, more stringent cement regulations, fracturing with more stages and high pumping rates on top of more cost-efficient well completion are raising demand for lightweight cements, which are designed to prevent damage and lost circulation problems in weaker formations. However, many alternative lightweight materials that are more cost effective than glass beads, which are known to provide superior strength, are increasing waiting-on-cement time, thus delaying further drilling. They also struggle to deliver the required compressive strengths. This paper presents (1) recent case histories of successful field applications of new stronger non-beaded lightweight cement, (2) extensive laboratory data of various field designs with new lightweight cement versus premium commercial lightweight cements, and (3) detailed scientific study explaining how the innovative lightweight cement has provided superior fluid stability and set cement mechanical properties.

The successful field trials occurred in the Permian basin for all four wells on the same pad. About 400 bbl of the new lightweight cement at 10.5 lbm/gal density was delivered to complete each cementing job with 134°F BHST and 6,000-ft measured depth. The four wells were completed with the new lightweight cement, remarkably having no glass beads despite the extremely low density. Unlike the previous job designed with commercial lightweight cement, the new cement has provided far greater compressive strength and has shown faster (18 to 24 hr) strength development. During placement, the new lightweight cement slurry has demonstrated exceptional stability with fewer additives than the previous design, thus simplifying field operations. Multiple laboratory test data at different cement densities (10.5 to 14.5 lbm/gal) for other regions confirmed the enhanced performance of the new lightweight cement in both slurry form and set cement over conventional lightweight technologies. Detailed scientific study via X- ray Diffraction (XRD) explained how the new lightweight cement provided superior set cement performance.

The novelty of this work and invaluable contribution to the industry is the first successful field application of a newly developed micromaterial that provided a lighter, stronger, low-permeability, non-beaded cement that enhances wellbore integrity and provides better zonal isolation. New findings from XRD and Scanning Electron Microscopy (SEM) imaging techniques about the new micromaterial lightweight additive may provide insights for improving the performance of traditional materials.
Use of Wavelet Transform and Signal Processing Techniques for Inferring Interwell Connectivity in Waterflooding Operations
Authors: Unal Ebru , Siddiqui Fahd , Rezaei Ali , Eltaleb Ibrahim , Kabir Shah , Soliman Mohamed Y. , Dindoruk Birol
Published: September 2019

Inter-well connectivity (IWC) is one of the most significant properties when evaluating the success of a waterflood. This connectivity has been obtained from various physics-based methods such as simulations, tracers and using heuristics and semi-analytical tools like capacitance-resistance model (CRM). Production and injection data are a key piece of information required to compute the IWC. In this study, we present a new method for estimating IWC using signal processing techniques on the wavelet transform of the injection and production rate data.

First, the injection and production rates are subjected to multiresolution analysis using the wavelet transform to determine the detail coefficients. The variance of the detail coefficients is then computed and is ready to be processed using various signal processing techniques. Signal processing techniques such as cross-correlation, time lag, Spearman correlation, and Kendal correlation are used to identify the level of relationship between the processed injection and production data in wavelet scale space. Based on the correlation coefficients, a new IWC link parameter is proposed for characterizing the IWC between well pairs. The IWC link parameters between well pairs are then plotted for visual representation.

We created several simulation models for multi-well systems, established water-flood patterns, and for randomly placed wells to establish the new IWC link parameter. The resulting injection and production rates were analyzed using the methodology above and the new IWC link parameter is established in terms of cross-correlation coefficient. We also performed several simulations for a heterogenous reservoir to compute and compare the accuracy of the new IWC link parameter. Finally, the methodology is subjected to real field waterflooding, and compared against the CRM results, which shows a good agreement. The visual representation gives new insight into whether the connectivity is being affected by the reservoir or from near wellbore events (such as changes in skin).

This study integrates signal processing techniques and waterflood IWCs. Novel use of wavelet transforms coupled with variance for processing the injection and production rate data is proposed. It must be emphasized that wavelet is used in this context for processing and not for smoothing or data compression. Ultimately, this method can be implemented as a real-time automated monitoring system. Moreover, the new IWC link parameter provides insights by identifying problematic IWC, well-completion issues, and high perm channels for taking timely operational decisions.
Risk-Based Audit as a Strategic Tool for Improving Accountability in PSC System
Authors: Arifianto Hafidh , Putra Iswahyudi Sondi
Published: September 2019

Cost recovery is an integral part of Indonesian Production Sharing Contract (PSC). The mechanism function as an incentive to attract investment in oil and gas exploration and production. The separation of function in PSC between the government and the contractor leads an information asymmetry over cost recovery. This issue makes the cost recovery calculation vulnerable to manipulation. In the context of the agency problem, the audit on cost recovery is deemed crucial as the government procedure to secure its share from inappropriate reimbursed cost.

The paper presents the challenge of traditional cost recovery audit, and a proposal to implement a Risk-Based Audit (RBA) approach as a strategic monitoring tool over cost recovery. The RBA provides an efficient and effective audit practice to maintain audit quality. The paper also adds to the literature on the government practice in addressing agency problem in PSC's cost reimbursement system based on a case study in Indonesian PSC environment.
Laboratory and Field Testing of a Steam-Limiting Flow Control Device Developed for Thermal Applications
Authors: Lastiwka Marty , Burke Lyle H. , Booy Daniel , Chineme Emeka C. , Gaviria Fernando , Ortiz Julian D.
Published: September 2019

A review of laboratory and field testing of a new flow control device is presented in this paper. The device is designed specifically to limit steam breakthrough in thermal operations.

For the past few years, four companies operating Steam Assisted Gravity Drainage (SAGD) facilities in Alberta's oil sands have come together to study downhole Flow Control Devices (FCDs) in a laboratory setting and to share field data of the application of such devices. Within this collaboration, a new device was designed to address the challenge specific to thermal operations, namely limiting steam breakthrough into production wells. Laboratory tests were undertaken to define the steam-limiting characteristics of this device under field representative SAGD conditions at full scale rates, temperatures and pressures. Tests were performed with oil to gauge viscosity sensitivity, as well as with water and steam at various inflow rates, temperatures and steam qualities. Testing was also performed with Non-Condensable Gas (NCG) to help assess how methane production may affect performance under both low and high Gas Volume Fraction (GVF) conditions. Finally, three-phase erosion testing was performed using water, quartz and air, allowing a realistic, scalable assessment of the device's long-term reliability.

Highlights from these tests are reported and compared to results from testing of conventional, commercially available devices. The new device has shown superior performance relative to other devices designed for non-thermal applications. Thus, it inhibits the influx of steam while allowing the flow of emulsion into a production well. Based on the results of laboratory testing, the device is currently being tested in field operations. Early indications are that the device is performing as expected. Preliminary field data are presented.

Laboratory testing of thermal flow control devices is especially challenging and unique when compared with similar testing for conventional flow control devices. This becomes more evident when testing devices designed specifically to limit steam breakthrough. Furthermore, in thermal operations, the phase change potential that is inherent when operating near the saturation point of water opens new possibilities in the design of flow control devices. A successful, practical implementation of this phase change characteristic was achieved in a collaborative environment.
Critical Sand Deposition Velocity in Intermittent Flow – Models Evaluation
Authors: Dabirian Ramin , Mohammadikharkeshi Mobina , Mohan Ram , Shoham Ovadia
Published: September 2019

Sand transport in multiphase flow has recently gained keen attention of the oil and gas industry owing to the negative effects associated with it. These include partial pipe blockage, pipe corrosion, excessive pressure drop and production decline. To date, no comprehensive literature review and models evaluation have been published, which compare the experimental data collected for the prediction of the critical sand deposition velocity under intermittent flow with the related model predictions. This study can be used by engineers and researchers to determine the conditions under which the developed models perform the best.

The intermittent flow critical sand deposition velocity data acquired by Najmi (2015) are presented in detail. Next, the effects of important parameters such as phase velocities, liquid viscosity as well as particle size and concentration on the critical velocity are investigated. The collected data are utilized to evaluate the performance of the models developed by Salama (1998), Hill (2011), Stevenson et al. (2001) and Danielson (2007), in order to determine the best model for the prediction of the sand critical velocity.

The experimental data of Najmi (2015) indicate that higher critical velocities are required with increasing the liquid viscosity, particle size and particle concentration. However, the predictions of the models of Salama (1998), Stevenson et al. (2001) and Danielson (2007) demonstrate that these models do not take into account the effect of particle concentration. Depending on the liquid viscosity, Stevenson et al. (2001) model significantly over-predicts or under-predicts the critical velocity over different ranges of the phase velocities, while Salama (1998) model under-predicts the critical velocity under all experimental conditions. An overall comparison of the data with the published model predictions confirms that the Hill (2011) model has the best performance capturing the physical phenomena, including the effects of phase velocities, particle size, particle concentration and liquid viscosity.
Deep Learning-Based Automatic Horizon Identification from Seismic Data
Authors: Gupta Harshit , Pradhan Siddhant , Gogia Rahul , Srirangarajan Seshan , Phirani Jyoti , Ranu Sayan
Published: September 2019

Horizons in a seismic image are geologically signficant surfaces that can be used for understanding geological structures and stratigraphy models. However, horizon tracking in seismic data is a time consuming and challenging task. Saving geologist's time from this seismic interpretation task is essential given the time constraints for the decision making in the oil & gas industry. We take advantage of the deep convolutional neural networks (CNN) to track the horizons directly from the seismic images. We propose a novel automatic seismic horizon tracking method that can reduce the time needed for interpretation, as well as increase the accuracy for the geologists. We show the performance comparison of the proposed CNN model for different training data set sizes and different methods of balancing the classes.
Formation Lithology Classification: Insights into Machine Learning Methods
Authors: Mohamed Ibrahim Mohamed , Mohamed Salah , Mazher Ibrahim , Chester Pieprzica
Published: September 2019

With the recent tremendous development in algorithms, computations power and availability of the enormous amount of data, the implementation of machine learning approach has spurred the interest in oil and gas industry and brings the data science and analytics into the forefront of our future energy. The idea of using automated algorithms to determine the rock facies is not new. However, the recent advancement in machine learning methods encourages to further research and revisit the supervised classification tasks, discuss the methodological limits and further improve machine learning approach and classification algorithms in rock facies classification from well-logging measurements. This paper demonstrates training different machine learning algorithms to classify and predict the geological facies using well logs data. Previous and recent research was done using supervised learning to predict the geological facies.

This paper compares the results from the supervised learning algorithms, unsupervised learning algorithms as well as a neural network machine learning algorithm. We further propose an integrated approach to dataset processing and feature selection. The well logs data used in this paper are for wells in the Anadarko Basin, Kansas. The dataset is divided into training, testing and evaluating wells used for testing the model. The objective is to evaluate the algorithms and limitations of each algorithm. We speculate that a simple supervised learning algorithm can yield score higher than neural network algorithm depending on the model parameter selected. Analysis for the parameter selection was done for all the models, and the optimum parameter was used for the corresponding classifier.

Our proposed neural network algorithm results score slightly higher than the supervised learning classifiers when evaluated with the cross-validation test data. It is concluded that it is important to calculate the accuracy within the adjacent layers as there are no definite boundaries between the layers. Our results indicate that calculating the accuracy of prediction with taking account the adjacent layers, yield higher accuracy than calculating accuracy within each point. The proposed feed-forward neural network classifier trains using backpropagation (gradient descent) provides accuracy within adjacent layers of 88%. Our integrated approach of data processing along with the neural network classifier provides more satisfactory results for the classification and prediction problem. Our finding indicates that utilizing simple supervised learning with an optimum model parameter yield comparable scores as a complex neural network classifier.
Hydrodynamics, Geothermics and Spatial Variations in Hydrocarbon Fluid Distribution within the Montney Formation, Alberta and British Columbia, Canada
Authors: Gibbs Allison , Rakhit Kaush
Published: September 2019

Hydrodynamics and geothermics are important tools for understanding the complex distribution of reservoir fluids in the Montney Formation in Alberta and British Columbia, Canada. The Montney comprises a conventional system in the east and an unconventional, Deep Basin-style hydrocarbon system in the west, where an underpressured, oil-dominated fairway just west and downdip of the conventional system grades further downdip into overpressured liquids and gas fairways.

The first part of this study addresses how these systems can be mapped from a pressure and temperature perspective. The Montney hydrodynamics system is explained using pressure versus elevation graphs. Key contours are taken from pressure-depth ratio maps to define the general boundaries between systems, noting that these boundaries change with depth. Geothermal gradient mapping is used to identify areas of prominent high or low geothermal gradients, which can have a significant effect on the positioning of gas liquids fairways. Key current day isotherms are also identified to represent the current phase windows by relating present-day formation temperatures to Tmax data.

To evaluate how pressure and temperature affect liquids production within the Montney, liquids production trends need to be considered. The second half of the paper discusses how mapping gas composition, particularly C2+ Wet Gas Index (WGI), may serve as a good proxy for liquids yields.

While the authors appreciate the complexities of phase behavior and the various factors influencing liquids production, the objective of this paper is to link trends that can be observed in liquids production to trends in pressure, temperature and gas composition. Ultimately, this paper examines ways in which hydrodynamics and geothermics can be used to help predict spatial variations in observed liquids production. By analyzing the co-relationships of the pressure, temperature and WGI data, the Montney segregates into two distinct domains which we term the Northern (British Columbia) Play and the Southern (Alberta) Play. This analysis can be tied in with other data sets for a better understanding of the reservoir such as: isotope geochemistry to gain insights into hydrocarbon migration; Special Core Analysis (SCAL) data to gain insights into fluid mobility; vapour-liquid equilibrium data to examine hydrocarbon fractionation during production; and completions data to provide a more complete picture of reservoir deliverability.
Dielectric Constant Interpretation: Comparison of the Salinity Dependence of the Real and Imaginary Response
Authors: Myers Michael
Published: September 2019

In this paper the dielectric constant of shaly sands both the real and imaginary parts is investigated and compared. An empirical model has been developed in the one MHz to one GHz frequency range for the real part of the dielectric constant. The equations developed involve the same pore systems as those governing the conductivity response. The dielectric constant contains an additionalfrequency independent high frequency limit. The dispersive terms are due to the clays and interfacial phenomena. The salinity and frequency dependence of these parameters are then discussed.

This salinity dependence of the dielectric model is compared to the salinity dependence both predicted and measured for the conductivity. Conductive inclusions are modeled similar to previously published work (Myers 1989) The Hanai-Bruggeman equation plays the central role which is consistent with Archie's equation but allows for conductive inclusions. The model for dispersed clays incorporates the effects of clay geometry and demonstrates that the conductivity is intimately related to the geometry and length scales involved in the clay conduction. The increase in the effective clay-counter ion mobility with increasing salinity is due to the coupling between the conductivity of the clays and the conductivity of the brine. It also demonstrates that the shape of the conductivity curve depends on the ratio of intergranular to clay porosity.
Effectiveness Study of the Spectral Approach to Geostatistical Simulation
Authors: Ismagilov Niyaz , Popova Oksana , Trushin Artemii
Published: September 2019

The spectral simulation approach is a recently developed geostatistical method of stochastic reservoir property simulation. The method has theoretical advantages over classical methods and the present work studies its practical effectiveness applied to synthetic data and real case of oil reservoirs. The study provides analysis of simulations results and describes strengths and limitations of the spectral method as well as application domain where it is most efficient.

The spectral method is based on Fourier analysis of well log data and consists of three major steps: decomposition of the well logs into Fourier series, simulation of Fourier coefficients in the interwell space and reconstruction of synthetic logs at every lateral point as sum of the Fourier series. The method was implemented in a software application and was used by authors for simulation of three-dimensional reservoir properties.

The effectiveness of the spectral method was studied based on simulations of continuous variables on a synthetic model. Simulations performed by the spectral method were compared to simulation results obtained on the same data by the more traditional method of sequential Gaussian simulation (SGS) provided by a commercial software. Analysis of the results from quantitative and qualitative points of view showed that the spectral method performed better at reproducing vertical non-stationarities observed in well data.

Practical applicability of the spectral method was demonstrated by simulation of porosity on a real oil field model, characterized by increase of porosity along depth with higher values of porosity closer to the bottom of the simulated layer. It was shown that the spectral method handled better this type of heterogeneity and reproduced distribution of porosity along the vertical axis closer to that of well data.