bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated Loss Control and Prevention Technologies for Complex Deep Wells Based on Precise MPD
Authors: Wang Gang , Fan Honghai , Zhang Wei , Yang Yang , Han Zili , Wu Hongxuan , Li Wanjun , Li Jiaying , Zhou Tuo , Zhou Haiqiu , Liu Jitong
Published: April 2019

M15 well contains complex intervals, where anticlinal structures developed from faults make long mudstone barriers full of cracks, which makes it hard to predict pore pressure. Loss is one of the most serious problems during drilling and cementing, while blow out accidents happen sometimes. Previous casing programs hardly adjust to all complex intervals and conventional LCMs (loss control materials) play few roles. As a result, designated targets used to be rarely reached.

It is proved that low pressure intervals shall be isolated firmly and complex intervals as well as reservoirs should be developed in independent intervals, thus casing programs have been modified. 188 lab tests were finalized, including 180°C hot rolling, anti-contamination test, lubricity test and inhibition experiments, in order to develop a kind of organic salt mud system that has premium inhibition, plugging, lubricating, heat & salt resistance properties. Precise MPD (managed pressure drilling) techniques are recommended to achieve near-balance drilling operation, solving borehole instability problems to some extent.

In the second interval the organic salt mud system is applied, while logging and casing running may be accomplished in one time. Besides, strings can be tripped out smoothly and high pressure brine productive zones are drilled safely. φ339.7mm casing joints are set at the depth of 3848m in the second interval and φ244.5mm casing joints are set at the depth of 5177m in the third interval, in order that deeper complex formation may be developed in a separate casing interval in which precise MPD is applied with LCMs while drilling and compound plugging agents. Therefore, downhole pressure is precisely controlled and large cracks are plugged statically on 28 occasions. Designated targets have been all reached and 20 oil & gas productive layers have been developed.

Downhole complexities arising from loss and blowout have been solved in M15, where φ339.7mm casing was set at the deepest interval in CNPC overseas operation history, making a new record of safe drilling operation, borehole quality and cementing quality. More oil and gas productive zones have been discovered and all designated targets have been achieved. New drilling experience got from M15 has significant meanings in the development of similar blocks.
Petrophysical Evaluation of Gas Hydrates : Estimation of Hydrate Saturation, Krishna Godavari Basin, India
Authors: Baruah Promothes , Vangala Sampath Rao , K Murali
Published: April 2019

The Natural Gas Hydrate Program Expedition (NGHP) has been formed to explore and develop the gas hydrate resources of Indian subcontinent in three stages. The first stage was to identify the presence of gas hydrate deposits in Indian Offshore Basins and the second stage was to identify gas hydrate in sand rich geological setting within gas hydrate stability zone and suitable locations for production testing. During the second stage, 42 gas hydrate wells at 25 sites were completed in deep water areas of Krishna Godavari and Mahanadi offshore in Eastern Coast of India.

This paper provides an insight into formation evaluation techniques as effective tools of evaluating gas hydrate saturation. During the second stage of the expedition; LWD, wireline well log data and pressure cores were acquired and they have been used for estimation and validation of gas hydrate saturations. The gas hydrate saturation have been estimated by three methods viz., standard deterministic Archie method, probabilistic method using ELANPlus model and Density Magnetic Resonance (DMR) technique. This paper also emphasizes the estimation of gas hydrate saturation considering gas hydrate as a part of matrix in the ELANPlus model and validation with pressure core results.

In Petrophysical model, hydrate can be considered either as a pore-filling hydrocarbon (fluid) or as a matrix mineral (rock constituent). When it is assigned as a pore-filling hydrocarbon, the model calculates the matrix volumes & porosity and calculates the water saturation in the same way as the basic interpretation model. When the hydrate is considered as a constituent of the matrix in the model, hydrate volume is calculated and the hydrate saturation is then arrived at by dividing this volume by the total porosity.

Hydrate is invisible to Nuclear Magnetic Resonance (NMR) measurements. In DMR technique, the deficit in NMR porosity as compared to Density porosity is used to estimate the hydrate volume accurately.

Gas hydrate saturation estimation in one of the well drilled during the second stage of the expedition from Krishna Godavari basin is discussed in detail in this paper. Gas hydrate saturation estimated from DMR method is found to be close agreement with other methods such as deterministic Archie and ELANPlus based probabilistic methods. The gas hydrate saturation is found to be in the range of 20-60% in the considered well. The results have been validated with gas hydrate saturation obtained from pressure cores retrieved from the nearby core hole.

The present approach is to estimate gas hydrate saturation with different methods and validation with pressure core data to minimize uncertainty in estimation of petrophysical parameters for such type of unconventional reservoirs.
Integrated Reserves Management Using Portfolio Approach: A Case Study
Authors: Al-Bahar M. , Al-Sane A. , Bora A. , Kumar A. , Mendjoge A. , Dhote P. , Antonevich Y. , Back M. , Kassim A. , Mason D. , Sethi M. U. , Siddique E.
Published: April 2019

Management of oil and gas resources and reserves has always been complex process as the company’s portfolio consists of resource and reserves volumes with varying degrees of uncertainty and maturity levels of projects. Some of the hydrocarbon volumes are from resources that are highly uncertain and require technology imprevoments or breakthroughs. However, for strategy formulation of the country/company needs consideration of all hydrocarbon volumes that can generate value in the future. The prioritization of development strategies for its reservoirs based on rigorous technical and economic assessments while protecting the national interests is a challenging task.

Kuwait Oil Company (KOC) has been using multiple systems for both asset and business planning processes that is not optimized for faster turnaround. The proposed integrated and automated reserves management solution provided a structured environment for systematic economic evaluation and portfolio optimization. It facilitates the visualization of key reservoir parameters delivering full understanding of the forecasted reserves, production and economic potential of the entire company. It indentifies gaps between reserves and detailed development plans based on technical and commercial criteria. By Optimizing the project timing and economics results in reduction of budgetary expences, increase in portfolio revenue and greater confidence for the company. Ranking the investment opportunities helps in allocating resources appropriately amongst different projects in a systemic manner to ensure profitability of the company. This approach provides ease to KOC in modeling complex scenarios and quickly evaluate a wide range of different development strategies catering for risk and uncertainty

This paper describes current industry challenges in resource and reservoir management, and an integrated approach to reserves, economics and portfolio management envisioned for Kuwait Oil Company (KOC) which will assist in identifying optimal reservoir development options to meet any defined strategic goals. The results and benefits gained after deployment of pilot will also be explained in the paper. This integrated approach for optimization of Asset Action Plans is a unique solution and would prove beneficial for our industry.
Extending the Curve – Drilling Medium Radius Horizontal Well in Low Cost Environment
Authors: Baheti Murli Manohar , Sinha Pankaj , Prabhakaran Tushar , Paliwal Kunal , Sharma Anurag , Doodraj Sunil , Vermani Sanjeev
Published: April 2019

The paper presents a case study on adopting an economics driven novel approach to directional well planning and drilling a horizontal well in a single well FDP (field development plan) for a marginal field in onshore India. The paper highlights the successful drilling of 8-1/2″ landing production section with DLS > 7 deg/30m followed by the 8-1/2″ horizontal lateral. The feasibility of achieving high DLS well trajectory using basic directional tools and associated hole problems with their mitigations are addressed in the paper.

Low crude price resulted in marginal economics for the above FDP. To improve economics, the capital expenditure had to be minimized (by utilizing existing well pads and production facilities) and maximize oil production (by drilling horizontal wells). Hence, constrained surface locations and fixed subsurface targets resulted in complex well trajectory (DLS>7). The Trajectory was finalized after multiple iterations to ensure that it is meeting requirements of deep set artificial lift, free of collision threats and also meeting the geological objective of placing the well in a thin reservoir with defined GOC and OWC. The final well design included one 12 ¼″ surface section with 9-5/8″ casing and 8-1/2″ production hole with 7″ casing to TD (~1800m MD). The well was initially planned with special RSS tool which could achieve high DLS, but the cost and lead time were the contra-indicators. Hence, the 8-1/2″ hole was planned with two BHAs. The build and land section was planned with motor (1.6 deg bend and rpm limitations) and tricone bit BHA to build from 9 deg to 90 deg inclination with a DLS of 7 deg/30m in 400m closure. The horizontal lateral was planned with RSS BHA and PDC bit including density image LWD for geosteering. To minimize hole sections for cost reduction, the landing and horizontal section was combined in a single hole which increased risk associated with wellbore stability, hole cleaning and casing running. The risks were suitably addressed through in-house geo-mechanics inputs, application of ERD procedures & real time T&D monitoring

With no offset well data (in onshore India) to substantiate the possibility of achieving high DLS trajectory, the motor and tricone bit BHA successfully achieved the desired trajectory with max DLS ~11deg/30m and without any hole problems. The well was successfully landed and placed in the reservoir. The operator gained significant confidence in understanding of drilling high DLS wells without expensive drilling tools
Challenges in Selection and Using of Production Chemicals with CEOR Operations During Polymer Breakthrough Phase
Authors: Zagitov Robert , Venkat Panneer Selvam , Kothandan Ravindranthan , Senthur Sundar , Ramanathan Sabarinathan
Published: April 2019

Enhanced Oil Recovery is important stage of life cycle of a field and often it is implemented with challenges. In the chemical EOR, challenges and surprises are expected in production chemistry and production facilities operations. Partially hydrolyzed polyacrylamide used widely for controlling mobility ratio so that Operator is able to recover maximum possible oil. With complex water chemistry and rich in positively charged divalent ions, flooded polymer having negative charge interacts with divalent ions of produced water. Back produced sheared polymer interacts with divalent ions to form semi hard to hard scales poses challenges of the reliability of production facilities.

Other important limitations to be noted in CEOR phase are using production chemicals to control scale, emulsion and microbial treatment under Hydrogen Sulphide and waxy crude environment. This paper discusses about the requirement of preparedness and how to overcome challenges of EOR operations and in handling the back produced polymer in following areas: Selection of production chemicals to be compatible to polymer so that no or minimal degradation or loss of viscosity due to polarity of chemicalsPerformance of production chemicals in the presence of polymerSolids loading in production system Emulsion and produced water treatmentSuitability of produced water treatment facilities Revised scaling and fouling control with back produced polymer with rich divalent ions present in produced waterStrategizing chemical management system to suit polymer flood and polymerized back produced water treatment regime
Design and Development of a Novel Fluid Loss Additive for Invert Emulsion Drilling Fluids from a Renewable Raw Material
Authors: Maghrabi Shadaab , Smith Delores , Engel Aaron , Henry Jennifer , Fandel Joseph
Published: April 2019

Commonly used fluid loss additives (FLAs) in today's invert emulsion drilling fluids include materials with various attributes. The unmet needs of existing materials may include: Environmental restrictions due to ecotoxicity or biodegradability concernsPerformance issues at high temperaturesOverdosing at high temperaturesHigh costsFormation damage

To address these challenges, a FLA was developed for invert emulsion drilling fluids that is made from a renewable raw material and performs at high temperature and high pressure. The renewable raw material used to make this novel FLA is a biopolymer byproduct of the paper pulping process, and was chemically modified under controlled conditions to create a high-performing FLA. Detailed testing was done to determine the additive's performance in different base oils (mineral and diesel), at various mud weights (12 to 16 ppg), at elevated temperatures and in different fluid systems characterized by rheology and high-pressure, high-temperature (HPHT) fluid loss. The novel FLA was compared to other commercially available FLAs for fluid loss performance.

The novel FLA outperformed or was on par with the industry available FLAs tested in this study. The novel FLA realized comparable fluid loss performance of less than 10 ml at 375 F at lower concentrations as compared to the industry FLAs. In some cases, the novel FLA performed at higher temperatures, whereas some of the industry available FLAs did not. The novel FLA also boosted the electrical stability (ES) of the emulsion in certain fluid systems. The novel FLA showed minimum change in the rheology of the oil-based fluids as compared to the industry available FLAs. The novel FLA demonstrated reasonable performance in different mud weights, base oils and fluid systems. Since this novel FLA is derived from a renewable raw material, it may have less of an environmental impact compared to other FLAs utilized today.

The novel FLA: Was developed from a renewable raw material for invert emulsion drilling fluids;Performed on par or outperformed industry available FLAs; andBoosted the ES of the emulsion for certain fluid systems.
Investigating Optimized Well Placement in San Andres Tight Oil Dolomite Reservoir by Integrated Reservoir Modeling Approach
Authors: Yang Junjie , Karam Pierre , Cozyris Kristian , Hustak Crystal , Doherty James , Allen Carmen
Published: April 2019

As a well-known tight oil dolomite reservoir in Texas, San Andres formation has attracted broad attention about horizontal drilling and development strategy. To optimize the oil recovery and asset’s economics, the aim of the study was to use an integrated approach to understand reservoir heterogeneity and performance, determine optimal landing zone and its impact on production, understand fracture geometry using different pumping schedules, and the optimal cluster spacing. In addition, the potential benefit of a refrac and infill drilling program was also investigated.

To tackle the optimization problem, an integrated reservoir modeling workflow was developed. Starting with a 1-D geomechanical model which captures the in situ stress profile and rock mechanics, hydraulic fracture modeling was developed to history match the treatment process, and therefore a comprehensive fracture geometry can be estimated. In the interim, a geological model with populated reservoir properties was established based on the offset data including petrophysical logs, imaging logs and cores. After calibration, the dynamic reservoir model was built to test multiple sensitivity runs for an optimized field development strategy.

Geological modeling separated the field into two models to study the variation of properties on the east and west side. The east section shows a higher porosity and lower saturations. Those water saturations increase below the main pay zone indicating a potential water source. In addition, special core analysis shows a strong oil-wet nature of the reservoir rock. In the east section, sensitivity runs included infill development and variations in landing depth. It is noted that the production is not sensitive to landing zone because fracture geometry is primarily controlled by vertical stress profile. In the west section, sensitivity runs included refrac, infill drilling, and a greenfield development plan with variations on well spacing and completion design. The observation shows tighter well spacing or cluster spacing accelerates the oil production in early time, while yielding similar long term oil recovery and shows a combination of refrac and infill drilling yields a 21% incremental oil production beyond the base case.

This study provides valuable information about the workflow to develop tight oil plays by describing a detailed case study. The result also sheds light on the optimized field development strategy for analogous fields.
Does Higher Viscosity Improve Proppant Transport?
Authors: Galindo Tanhee
Published: April 2019

The use of high viscosity friction reducers (HVFR) as alternatives to guar-based fluids to improve proppant transport and lessen formation damage has increased rapidly. While several product options are available, the criteria for selection of a product has focused on viscosity at 300 RPM (511s-1) that meets or exceeds that of linear gel fluids. However, there has been limited data available on what the target viscosity should be, how it influences the fluid's ability to transport sand, and the potential for damage to proppant conductivity. This study presents methodology used to screen HVFR's and results on product performance, which identified a need for alternative specifications to viscosity to achieve maximum performance.

The proppant transport capacity in dynamic conditions was evaluated for twenty-eight commercially available friction reducers and HVFR's in field waters which could have up to 40,000 TDS. A slot flow apparatus was used to mimic fluid flow through a fracture under different shear and flow rate conditions. Viscosity and elasticity measurements were also obtained using an advanced rotational rheometer. For comparison, linear gel and crosslinked guar fluid were also evaluated.

While viscosity at 300 RPM (511s-1) and more recently high viscosity at lower shear rates, have been used for selection of HVFR's, these parameters alone do not indicate proppant carrying capacity. The authors did not find a correlation between higher viscosity and better proppant transport, rather they propose that too high a viscosity can negatively impact transport. The results provided insight into the effect of flow rate on proppant transport, with some HVFR's that exhibited higher viscosities at low shear, losing their transport capacity at the same low shear. Elasticity testing of those same products suggested that HVFR's have a critical elasticity range at which they will provide optimal performance. Polymer residuals were also evaluated on proppant post-test and compared to traditional linear gels and crosslinked fluids. Results suggested potential for damage if HVFR's are used without breakers. Different viscosity targets should be set when selecting a HVFR and coupled with other testing criteria such as elasticity and dynamic proppant transport.

This paper provides insight into the need for development of standardized test criteria for HVFR selection. Further testing and screening of HVFR's will help increase the understanding of key factors influencing sand transport and their effect on proppant pack conductivity.
Model for Asymmetric Hydraulic Fractures with Non-Uniform Stress Distribution
Authors: Hu Xiaofan , Liu Guoqing , Luo Guofan , Ehlig-Economides Christine
Published: April 2019

Engineers commonly expect symmetric fracture wings in multiple transverse fracture horizontal wells (MTFHWs). Microseismic surveys have shown asymmetric hydraulic fracture grow away from the recent fractured wells and grow towards previous produced wells. It might be caused by the elevated stress around the recently fractured well and the reduced stress near the depleted wells. This paper presents the asymmetric fracture growth observed by the microseismic events and develops a simple model to simulate the fracture propagation and its impact on the well productivity.

Motivated by the microseismic observations, we developed a simple fracture model to simulate asymmetric fracture wings that can capture the behavior of fracture hits between two adjacent horizontal fractured wells. Also, we developed a model to estimate the productivity of a well with asymmetric fractures.

The newly developed fracture model shows that the fracture can grow asymmetrically if the horizontal well is located where stress field is different between its two sides. The productivity model for asymmetric hydraulic fractures quantifies the penalty to the well performance. Results provide a reason why asymmetric fractures happen and that they do penalize well performance. Our models suggest the importance of fracturing under balanced stress distribution which benefits the long-term production. Use of the model suggested an optimized hydraulic fracturing treatment design will improve the overall performance of multiple parallel wells that minimizes or avoids asymmetric fracture wings.

The fracture propagation model and productivity model provide simple, but profound, guidelines for the well pad management, including well spacing, stage planning and spacing, completion and production order.
Dimensionless Section-Level Cumulative Oil Vs. Pumped Fluid Normalization Plot in Unconventional Development
Authors: Rosenhagen Nicolas M. , Nash Steven D. , Dobbs Walter C. , Tanner Kevin V.
Published: April 2019

The volume of stimulation fluid injected during hydraulic fracturing is a key performance driver in the horizontal development of the Niobrara formation in the Denver-Julesburg (DJ) Basin, Colorado. Oil production per well generally increases with stimulation fluid volume. Often, operators normalize both production and fluid volume based on stimulated lateral length and investigate relationships using "per-ft" variables. However, data from well-based approaches commonly display such wide distributions that no useful relationships can be inferred. To improve data correlations, multivariate analysis normalizes for parameters such as thermal maturity, depth, depletion, proppant intensity, drawdown, geology and completion design. Although advancements in computing power have decreased cycle times for multivariate analysis, preparing a clean dataset for thousands of wells remains challenging. A proposed analytical method using publicly available data allows interpreters to see through the noise and find informative correlations.

Using a data set of over 5000 wells, we aggregate cumulative oil production and stimulation fluid volumes to a per-section basis then normalize by hydrocarbon pore volume (HCPV) per section. Dimensionless section-level Cumulative Oil versus Stimulation Fluid Plots ("Normalization" or "N-Plot") present data distributions sufficiently well-defined to provide an interpretation and design basis of well spacing and stimulation fluid volumes for multi-well development. When coupled with geologic characterization, the trends guide further refinement of development optimization and well performance predictions.

Two example applications using the N-Plot are introduced. The first involves construction of predictive production models and associated evaluation of alternative development scenarios with different combinations of well spacing and completion fluid intensity. The second involves "just-in-time" modification of fluid intensity for drilled but uncompleted wells (DUC's) to optimize cost-forward project economics in an evolving commodity price environment.
Fast-Loop Quantitative Analysis of Proppant Distribution Among Perforation Clusters
Authors: Kortukov Dmitry , Williams Michael
Published: April 2019

Using optical fibers to instrument hydraulically fractured wells is becoming routine in US unconventional plays. Instrumented wells facilitate understanding of proppant distribution among perforation clusters and the inefficiencies of geometric fracturing and well planning techniques. However, converting fiber-optic data into proppant distribution requires management of high volumes of data and correlation of the data to factors such as well conditions, fracturing parameters, and temperatures. A user-friendly workflow for understanding hydraulic fracturing proppant and slurry distribution among different perforation clusters over time is presented. Ideally, slurry flow is equal between perforation clusters and, at least, constant in time, but the reality is very different. The interpretation workflow is based on proprietary algorithms within a general wellbore software platform and aims to greatly expedite the analysis. We propose using distributed acoustic sensing (DAS) data (in the form of custom frequency band energy (FBE) logs), distributed temperature measurements (DTS) and surface pumping data to obtain a quantitative analysis of proppant distribution within minutes, with various options for reporting and visualizing results. The software platform selected provides data integration, visualization, and customization of in-built algorithms. The new workflow enables users to upload DAS, DTS, flow rate, pressure, and other measurements and use customized algorithms to quantitatively analyze proppant distribution, enabling decisions in real time to optimize the fracturing operation. The validity of the approach is illustrated by a case study involving a well with 28 stages and four to five clusters per stage. The workflow is automated to provide results in real time, enabling quick corrective actions and significantly improving the efficiency and economics of hydraulic fracturing.
A Kinetic Monte Carlo Study to Investigate the Effective Permeability and Conductivity of Microfractures within Unconventional Reservoirs
Authors: Inyang Ubong , Cortez-Montalvo Janette , Dusterhoft Ron , Apostolopoulou Maria , Striolo Alberto , Stamatakis Michail
Published: April 2019

Estimating the effective permeability and microfracture (MF) conductivity for unconventional reservoirs can be challenging; however, a new method for estimating using a stochastic approach is discussed. This new analysis method estimates matrix permeability and the unpropped and propped MF conductivities during laboratory testing where MFs were propped with ultrafine particles (UFPs).

Kinetic Monte Carlo (KMC) simulations form the basis of the method used to estimate effective permeability of the core sample. First, the stochastic model was implemented to calculate effective matrix permeability of a small core taken from unfractured Eagle Ford and Marcellus formation samples using scanning electron microscopy (SEM) images and adsorption data to obtain the pore-size distribution (PSD) within the sample. The KMC approach then evaluated the effect of various parameters influencing the conductivity of laboratory-created MFs. Case studies considered for this work investigate the conductivity improvement of a manmade MF as a function of the UFPs used as proppants that maintain width under high stress, the UFP (proppant) concentration, and the UFP flow perpendicular into a secondary or adjacent MF zone (2ndMF) penetrating the face of an opened MF during flow testing under stress. The leakoff area widths considered were 1, 2, and 3 mm and can be propped or unpropped.

Results obtained for the unfractured Eagle Ford and Marcellus samples closely correlate with other computational and experimental data available. For the laboratory-prepared nonpropped and propped MF samples, the effective propped width was determined to have the greatest effect on the MF conductivity, which increased by two orders of magnitude in the presence of the UFPs. The remaining two factors—proppant concentration and length of 2ndMFs—helped improve the effective MF conductivity in a linear manner; the highest proppant concentration and the 2ndMF zone resulted in the highest fracture conductivity achieved. Insight obtained from this study can be used to optimize fracturing designs by including UFPs and to create strategies for maximizing hydrocarbon recovery during development of unconventional resources where MFs are opened during stimulation treatments.
Fracture Diagnostic Using Distributed Temperature Measurements During Stimulation Fluid Flow-Back
Authors: Mao Yilin , Zeidouni Mehdi , Godefroy Caroline , Gysen Michel
Published: April 2019

The significant temperature difference between the fractured and non-fractured regions during the stimulation fluid flow-back period can be very useful for fracture diagnosis. The recent developments in downhole temperature monitoring systems open new possibilities to detect these temperature variations to perform production logging analyses. In this work, we derive a novel analytical solution to model the temperature signal associated with the shut-in during flow-back and production periods. The temperature behavior can infer the efficiency of each fracture. To obtain the analytical solution from an existing wellbore fluid energy balance equation, we use the Method of Characteristics with the input of a relevant thermal boundary condition. The temperature modeling results acquired from this analytical solution are validated against those from a finite element model for multiple cases.

Compared to the warm-back effect in the non-fractured region after shut-in, a less significant heating effect is observed in the fractured region because of the warmer fluid away from the perforation moving into the fracture (after-flow). Detailed parametric analyses are conducted on after-flow velocity and its variation, flowing, geothermal, and inflow temperature of each fracture, surrounding temperature field, and casing radius to investigate their impacts on the wellbore fluid temperature modeling results.

The inversion procedures characterize each fracture considering the exponential distribution of temperature based on the analytical solutions in fractured and non-fractured regions. Inflow fluid temperature, surrounding temperature field, and after-flow velocity of each fracture can be estimated from the measured temperature data, which present decent accuracies analyzing synthetic temperature signal. The outputs of this work can contribute to production logging, warm-back, and wellbore storage analyses to achieve successful fracture diagnostic.
Investigate The Rheological Behavior of High Viscosity Friction Reducer Fracture Fluid and Its Impact on Proppant Static Settling Velocity
Authors: Ba Geri Mohammed , Imqam Abdulmohsin , Bogdan Andrey , Shen Lingjuan
Published: April 2019

The recent and rapid success of using high viscosity friction reducers (HVFRs) in hydraulic fracturing treatments is due to several advantages over other fracture fluids (e.g. linear gel), which include better proppant carrying capability, induce more complex fracture system network with higher fracture length, and overall lower costs due to fewer chemicals and less equipment on location. However, some concerns remain, like how HVFRs rheological properties can have impact on proppant transport into fractures. The objective of this study is to provide a comprehensive understanding of the influence the rheological characterization of HVFRs have on proppant static settling velocity within hydraulic fracturing process. To address these concerns, comprehensive rheological tests including viscosity profile, elasticity profile, and thermal stability were conducted for both HVFR and linear gel. In the steady shear-viscosity measurement, viscosity behavior versus a wide range of shear rates was studied. Moreover, the influence of elasticity was examined by performing oscillatory-shear tests over the range of frequencies. Normal stress was the other elasticity factor examined to evaluate elastic properties. Also, the Weissenberg number was calculated to determine the elastic to viscous forces. Lastly, quantitative and qualitative measurements were carried out to study proppant settling velocity in the fluids made from HVFRs and linear gel. The results of rheological measurement reveal that a lower concentration of HVFR-2 loading at 2gpt has approximately more than 8 times the viscosity of linear gel loading at 20ppt. Elastic measurement exposes that generally HVFRs have a much higher relaxation time compared to linear gel. Interestingly, the normal stress N1 of HVFR-2, 2gpt was over 3 times that of linear gel loading 20ppt. This could conclude that linear gel fracture fluids have weak elastic characterization compared to HVFR. The results also concluded that at 80 C° linear gel has a weak thermal stability while HVFR-2 loses its properties only slightly with increasing temperature. HVFR-2 showed better proppant settling velocity relative to guar-based fluids. The reduction on proppant settling velocity exceed 75% when HVFR-2 loading at 2gpt was used compared to 20ppt of linear gel. Even though much work was performed to understand the proppant settling velocity, not much experimental work has investigated the HVFR behavior on the static proppant settling velocity measurements. This paper will provide a better understanding of the distinct changes of the mechanical characterization on the HVFRs which could be used as guidance for fracture engineers to design and select better high viscous friction reducers.
Evaluating Pressure Drawdown Strategy for Hydraulically Fracture Shale Gas Condensate Producers
Authors: Rodriguez Alfonso , Maldonado Francisco
Published: April 2019

Managing adequately pressure drawdown should be a key technical reservoir management driver due to its major impact on cash flow, acceleration and final recovery factor for operating hydraulically fracture shale gas condensate producers. Permeability should be regarded as a key dynamic property for ultra-low permeability shale reservoirs that influences shale hydrocarbon recovery. It is paramount to develop a pressure depletion plan that captures the pressure drawdown strategy and the changes in flow capacity associated to the interaction of the nano-Darcy rock and hydraulic fractures with stress dependent permeability effects.

Defining the adequate drawdown strategy would aid maximizing the economic recovery. Considering the variability of permeability with pressure drawdown should be part of the reservoir management lifecycle for unconventional shale reservoirs. This study focus on evaluating the impact of pressure drawdown strategy on initial rates and recovery for a Duvernay Gas condensate producer with an initial condensate yield of 100-150 stb/mmscf.

A sector compositional reservoir simulation model was built for a horizontal multistage hydraulically fracture Duvernay shale gas condensate producer. A full assessment of variability of permeability in the nano-Darcy rock and in the propped hydraulic fracture stages near the wellbore region was accomplished. Aggressive, moderate and conservative pressure drawdown strategies were evaluated, considering multiple operational pressure drawdown incremental ranges from 14.5 to 95 psia per day.

Results clearly indicate that implementing daily pressure drawdown increments of 22 to 29 psia per day would provide a similar recovery factor than imposing daily pressure drawdowns of 44 to 95 psia per day. However, there is a golden operating window opportunity to accelerate recovery by imposing maximum drawdown from the early days of production and bringing significant benefits of accelerating recovery with an associate increase in revenue but the benefits of this acceleration vanished in less than one year due to substantial changes in hydraulic fracture conductivity and also in the nano-Darcy rock permeability in the near wellbore region. The reduction of nano-Darcy permeability is a function of pressure, time and distance from the hydraulic fractures. According to our results, the best reservoir management practice for operating lean/medium Gas Condensate unconventional shale producers should be maximizing pressure drawdown at the early stage of the life cycle and deferring the installation of production string to maximize inflow-outflow.
Combining State-of-the-Art Hybrid Bit and Positive Displacement Motors Saves 863,670 CAD Over 20 Wells in Northern Alberta, Canada
Authors: Blakney Donya , Cripps Evan , Quintero Jonathan , Bradshaw Robert , Belloso Andres , Glass Darnell , Hurlburt Maurice
Published: April 2019

A Canadian oil & gas operator has been setting new benchmarks drilling the vertical and tangent section of Montney horizontal wells in the Placid field of Northern Alberta. Initially, the operator drilled vertical wells to kick off point (KOP) with polycrystalline diamond compacts (PDC) and conventional mud motors. As a result of increasing well density, however, the well plans consistently required a 15° to 30° tangent section. With PDC drilling, toolface and build up rates were problematic and the sliding rate of penetration (ROP) was slow.

A Rotary Steerable System (RSS) was introduced, but despite the improved performance, the technology came at a premium cost and the severity of drilling dysfunctions generated an increase in tool failures. With falling oil prices, a more cost effective solution was required.

Hybrid bit technology, which combines the cutting mechanism of both fixed cutter and roller-cone bits, has been extensively utilized in Canada to drill build sections, providing outstanding results. They have not, however, been commonly used to drill the vertical (drill-out) and tangent sections. The operator combined a state-of-the-art hybrid bit with a mud motor to drill the interval with an 85% success rate. The combination of the hybrid bit and conventional motor, compared to PDC and RSS, resulted in a 30% cost savings to complete the interval.

The present case study outlines how hybrid bit technology development, driven by field data in a continuous improvement cycle, identifies performance opportunities, which have a significant impact on drilling time and cost savings in drill out sections. The overall objective of this current case study is to highlight the results and lessons learned throughout the implementation process.
THE COMPREHENSIVE ASSESSMENT OF THE EFFECTIVENESS OF ACTIVITIES AIMED TO CONTROL THE SPREAD OF HIV/TB CO-INFECTION IN NORTH-WEST RUSSIA
Authors: Zagdyn Z. M. , Verbitskaya E. V. , Sokolovich E. G. , Belyakov N. A.
Published: April 2019

In Russia, the downward trends in tuberculosis transmission are leveled by the growing HIV infection spread. In order to improve the situation, it is necessary to know the strengths and weaknesses of tuberculosis control activities among people living with HIV. The objective of the study: the comprehensive assessment of the effectiveness of activities aimed to control the spread of HIV/TB co-infection in North-West Russia. Subjects and methods. The authors used epidemiological and clinical-diagnostic methods, ranking, correlation analysis, and expert assessment. The epidemiological and clinical analyses were based on the reporting forms of Rosstat on tuberculosis and HIV, data from analytical reports on monitoring visits and data from the questionnaires developed by the authors, for 2007-2017. The correlation between the studied parameters was assessed using Spearman's rank correlation. Results. In North-West Russia, the main tuberculosis control activities among people living with HIV, including logistical support and provision of personnel (Spearman's rank ratio (-0.32177), p < 0.05), a set of preventive measures aimed at the coverage with antiretroviral therapy, preventive treatment and screening for tuberculosis in HIV-positive people (Spearman's rank ratio (-0.03226), p > 0.05) did not provide any statistically significant impact on the spread of HIV/TB co-infection, which indicated of their imperfection and inequality. Conclusion. In the North-West of Russia, the system aimed to control the spread of HIV/TB co-infection requires some optimization.
Estrategias de planificación para datos y procesos en computación Grid: estado del arte
Authors: Vargas Bermúdez Francisco Arnaldo , Báez Pérez Carmen Inés
Published: April 2019

La distribución y la naturaleza compartida y heterogénea de la computación grid, hace que su objetivo de ofrecer aplicaciones con poder computacional colectivo, sea un gran reto. El objetivo es presentar el resultado de una investigación sistemática sobre aspectos teóricos de las temáticas que convergen en el diseño y desarrollo de planificadores de datos y procesos en computación grid. Se tomó como referente la metodología planteada para desarrollo de estados de arte, que cuenta con dos fases principales: heurística y hermenéutica. En el proceso se analizaron los fundamentos teóricos, tales como: la arquitectura, las etapas que conforman el proceso realizado por parte de un planificador grid y los tipos de planificación existentes, todo ello con el objeto de abordar los diferentes modelos y enfoques computacionales, heurísticos y metaheurísticos que permiten un funcionamiento eficiente y eficaz de manera óptima de los planificadores grid, permitiendo mitigar en cierto grado los problemas presentados en la planificación grid. La optimización de la planificación de recursos grid, es un área que se encuentra en desarrollo, dado que las problemáticas principales como: demora en la planificación y el proceso de optimización, están aún en etapa de desarrollo.
Cognitive analytical tools for cost management of innovation activity
Authors: Labunska Svitlana , Karaszewski Robert , Prokopishyna Olena , Iermachenko Iegor
Published: April 2019

Promotion of innovations on the market is hampered in Ukraine by the lack of methodological approaches for analyzing the efficiency of innovative projects. The lack of appropriate methodology leads companies to refuse to innovate because of the uncertainty of final economic outcomes. The introduction of project based methods for innovation activity management allows, on the one hand, to reconcile strategic and operational objectives within the innovation process, innovation activity and general financial and economic activity of the enterprise, and on the other hand, to implement cognitive approaches to organization of company’s innovation management.The research argues the possibilities of applying the canonical correlation method for structuring the causal links between the determined components of a company innovative capability, such as innovation potential, innovative business opportunities and system margin. As these components may be further assessed by quantitative indices, the method of regression analysis is also used to develop analytical tools for innovation management, which allow to reveal the interrelated impact of expenses on the results of innovation activity. The paper analyzes changes in a company innovative capability that can be provoked by increased material, depreciation, labor and information costs and discusses directions of interrelated changes. Practical testing of submitted proposals is realized based on the Ukrainian companies’ statements for 2012–2017.
Sign-constrained linear regression for prediction of microbe concentration based on water quality datasets
Authors: Kato Tsuyoshi , Kobayashi Ayano , Oishi Wakana , Kadoya Syun-suke , Okabe Satoshi , Ohta Naoya , Amarasiri Mohan , Sano Daisuke
Published: April 2019

This study presents a novel methodology for estimating the concentration of environmental pollutants in water, such as pathogens, based on environmental parameters. The scientific uniqueness of this study is the prevention of excess conformity in the model fitting by applying domain knowledge, which is the accumulated scientific knowledge regarding the correlations between response and explanatory variables. Sign constraints were used to express domain knowledge, and the effect of the sign constraints on the prediction performance using censored datasets was investigated. As a result, we confirmed that sign constraints made prediction more accurate compared to conventional sign-free approaches. The most remarkable technical contribution of this study is the finding that the sign constraints can be incorporated in the estimation of the correlation coefficient in Tobit analysis. We developed effective and numerically stable algorithms for fitting a model to datasets under the sign constraints. This novel algorithm is applicable to a wide variety of the prediction of pollutant contamination level, including the pathogen concentrations in water.

This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.
Symmetry properties of fractional order transport equations
Authors: Gazizov R.K. , Kasatkin A.A. , Lukashchuk S.Yu.
Published: April 2019

In the paper some features of applying Lie group analysis methods to fractional differential equations are considered. The problem related to point change of variables in the fractional differentiation operator is discussed and some general form of transformation that conserves the form of Riemann-Liouville fractional operator is obtained. The prolongation formula for extending an infinitesimal operator of a group to fractional derivative with respect to arbitrary function is presented. Provided simple example illustrates the necessity of considering both local and non-local symmetries for fractional differential equations in particular cases including the initial conditions. The equivalence transformation forms for some fractional differential equations are discussed and results of group classification of the wave-diffusion equation are presented. Some examples of constructing particular exact solutions of fractional transport equation are given, based on the Lie group methods and the method of invariant subspaces.
Acoustic waves in two-fraction mixtures of liquid with vapor-gas bubbles
Authors: Gafiyatov R.N.
Published: April 2019

The mathematical model of two-fractional mixture of liquid with vapor-gas bubbles of different gases and sizes with phase transformations is presented. The dispersive equation is received, dispersive curves that determine the propagation of acoustic disturbances was plotted. Calculations on the propagation of impulse pressure perturbations were performed by means of a fast Fourier transformation method.
Destruction of water-in-oil emulsions in electromagnetic fields in a dynamic mode
Authors: Kovaleva L.A. , Zinnatullin R.R. , Blagochinnov V.N. , Musin A.A. , Fatkhullina Yu.I. , Zamula Yu.S.
Published: April 2019

Some results of experimental and numerical studies of the influence of radio-frequency (RF) and microwave (MW) electromagnetic (EM) fields on water-in-oil emulsions are presented. A detailed investigation of the dependence of the dielectric properties of emulsions on the frequency of the field makes it possible to establish the most effective frequency range of the EM influence. The results of water-in-oil emulsion stability in the RF EM field depending on their dielectric properties are presented. The effect of the MW EM field on the emulsion in a dynamic mode has been studied experimentally. In an attempt to understand the mechanism of emulsion destruction the mathematical model for a single emulsion droplet dynamics in radio-frequency (RF) and microwave (MW) electromagnetic fields is formulated.