bluuebunny/crossref_metadata_2025_split huggingface dataset:
30 Years of Horizontal Production Logging. What are We Really Measuring?
Authors: Kotlar Nicolas 
Published: April 2019

Abstract
The objective of this work is to demonstrate that the choice of the conveyance method for Production Logging operations is key in horizontal wells, as it affects the flow dynamics and changes the well inflow performance compared to undisturbed flowing conditions. A case study is presented, showing that critical decisions to develop a field (or not) may have been wrongly influenced by Production Logging results, if the effects of the conveyance on the inflow distribution were not correctly understood.
Synthetic production logs and flowing pressure distributions along the horizontal section were computed, and sensitivities on conveyance method diameter (coiled tubing, tractor and cable), pipe diameter, well length and reservoir properties were also conducted. These results were compared with the normal well flowing conditions to establish the representativeness of the PL measurements. A method for simulating the undisturbed production profile is presented, which uses the results of a Multirate Production Logging and recomputed flowing pressures using nodal analysis.
The presence of the conveyance method alters the well's inflow performance and zonal contributions, due to the modifications of the flow geometry and additional frictional pressure drop. The bottomhole flowing pressure is disturbed, with lower pressures around the heel and higher towards the toe. The drawdown along the horizontal gets modified, acting as a preferential choke for production coming from the toe and increasing the driving force for production from the heel. The severity of the drawdown unbalance is a function of the induced frictional pressure, given by the pipe and conveyance diameter, well length, flow rates, etc. The simulations and sensitivities presented in this paper help to understand how significant the PL measurements are, and when these results become misleading. The case study supports these findings, where the pressure disturbance induced by the conveyance changed the flow distribution dramatically, wrongly indicating than an area of the field was relatively depleted compared to the zone around the heel. The lack of understanding of the impact of the conveyance method can lead to poor developmental decisions.
A Semi-Analytical Poroelastic Solution to Evaluate the Stability of a Borehole Drilled Through a Porous Medium Saturated with Two Immiscible Fluids
Authors: Gao Jia Jia , Lau Hon Chung , Sun Jin 
Published: April 2019

Abstract
Conventional drilling design tends to inaccurately predict the mud density needed for borehole stability because it assumes that the porous medium is fully saturated with a single fluid while in actuality it may have two or more fluids.
This paper provides a new semi-analytical poroelastic solution for the case of an inclined borehole subjected to non-hydrostatic stresses in a porous medium saturated with two immiscible fluids, namely, water and gas. The new solution is obtained under plane strain condition. The wellbore loading is decomposed into axisymmetric and deviatoric cases. The time-dependent field variables are obtained by performing the inversion of the Laplace transforms. Based on the expansion of Laplace transform solution, we derive the unsaturated poroelastic asymptotic solutions for early times and for a small radial distance from an inclined wellbore. The model is verified by analytical solutions for the limiting case of a formation saturated with a single fluid. The impact of the unsaturated poroelastic effect on pore pressure, stresses and borehole stability is investigated.
Our results show that the excess pore pressure due to the poroelastic effect is generally higher for the saturated case (water) than the unsaturated case due to the large difference between the compressibility of fluid phases (water and gas). The time-dependency of the poroelastic effect causes the safe mud pressure window of both the unsaturated and saturated cases to narrow and approach the long-time poroelastic one with increasing time. The safe mud pressure window narrows with increasing initial gas saturation. The commonly used assumption that the formation is fully saturated by one fluid (such as water) tends to be conservative in predicting the mud density required for borehole stability.
This new semi-analytical poroelastic solution enables the drilling engineer to more accurately estimate the time-dependent stresses and the pore pressure around a borehole, thus allowing him to design the mud weight to ensure borehole stability.
A Study on the Chemo-Mechanical Alteration of Cement in CO2 Storage Sites
Authors: Bagheri Mohammadreza , Shariatipour Seyed M. , Ganjian Eshmaiel 
Published: April 2019

Abstract
The fluid pressure, the stress due to the column of the cement in the annulus of oil and gas wells, and the radial pressure exerted on the cement sheath from the surrounding geological layers all affect the integrity of the cement sheath. This paper studies the impact of CO2-bearing fluids, coupled with the geomechanical alterations within the cement matrix on its integrity. These geochemical and geomechanical alterations within the cement matrix have been coupled to determine the cement lifespan. Two main scenarios including radial cracking and radial compaction, were assumed in order to investigate the behaviour of the cement matrix exposed to CO2-bearing fluids over long periods. If the radial pressure from the surrounding rocks on the cement matrix overcomes the strength of the degraded layers within the cement matrix, cement failure can be postponed, while on the other hand, high vertical stress on the cement matrix in the absence of a proper radial pressure can lead to a reduction in the cement lifespan. The radial cracking process generates local areas of high permeability around the outer face of the cement sheath. Our simulation results show at the shallower depths the cement matrices resist CO2-bearing fluids more and this delays exponentially the travel time of CO2-bearing fluids towards the Earth's surface. This is based on the evolution of CO2 gas from the aqueous phase due to the reduction in the fluid pressure at shallower depths, and consumption of CO2 in the reactions which occur at the deeper locations.
A Novel Approach to Discovery of Hidden Structures in Microseismic Data Using Machine Learning Techniques
Authors: Yatsenko Maxim , Brankovic Milan , Gildin Eduardo , Gibson Richard L. 
Published: April 2019

Abstract
The objective of this paper is to propose an alternative data analysis approach to working with microseismic data. Modern machine learning techniques, such as MWCA (Multiway Component Analysis) and TD (Tucker Decomposition) can give the capability to efficiently work with complex high-dimensional microseismic data structures. Using this method, it was possible to restore hidden information about the signal, compress the data, and get insights about fractures without using conventional time-consuming simulations. Therefore, it is an important addition to the hydraulic fracturing quality assessment. It is a cost-effective technique providing a greater degree of automation in comparison to conventional methods.
The approach was tested on synthetic data and relevant real microseismic data provided by a service company. The data was integrated in a 3rd-order tensor form where modes are: seismic events time, receiver locations, and event locations. The tensor was then decomposed into a core tensor and three factor matrices by means of a special form of TD called HOSVD (Higher-Order Singular Value Decomposition). HOSVD is a multidimensional decomposition used to extract low rank approximations of tensors. The MWCA technique was utilized to impose constraints on TD. HOSVD showed potential as a tool for a rapid fractures analysis by observing decomposed tensor structure. Additionally, the technique helped reduce the original model by 73% (supercompression).
The proposed workflow is general and highly applicable to various plays. Since the applications of MWCA and TD are still emerging, future enhancements to this methodology are expected. In turn, this will reveal further insights from microseismic data, making it paramount to optimal fracturing and improved field management.
Can Unconventional Completion Systems Revolutionise EGS? A Critical Technology Review
Authors: Guinot Frédéric , Meier Peter 
Published: April 2019

Abstract
The technical and economic successes of deep geothermal development rely on reducing drilling and completion risks. In the closely related oil and gas activities, the risk taken by the investors is balanced by the high reward that successful projects achieve by immensely offsetting the losses of the failed wellbores. Geothermal projects experience similar risks, however, the potential reward is limited by the competition with other energy sources, in a heavily regulated market. The economic acceptability of geothermal power generation requires low risk drilling and completion technologies that would work under many different geological conditions.
When wells are drilled into a petro-thermal formation, sometimes referred to as hot dry rock (HDR), there is normally no clear circulation path between these wells and when this path exists, the transmissivity is so low that no economical project is possible. Enhanced geothermal systems (EGS), in these circumstances is closer to reservoir creation than to conventional reservoir stimulation. Therefore, developing technologies that achieve the designed EGS size and transmissivity is vital to deep geothermal development.
The EGS becomes a viable proposition, when enough rock surface can be contacted by the geothermal fluid, and when the flow path runs smoothly through a sufficient rock volume to minimize the energy depletion and have the project running over a long period, compatible with a positive net present value (NPV). To that end, the well design and its completion system have to be engineered to maximize the chances of properly creating the EGS. In this paper, lessons learnt from past geothermal experience are reviewed and analysed to propose a multi-stage system as a mean of improving geothermal wells completion reliability. Current oil and gas (namely "unconventional") completion technologies related to multi-stage stimulation have been reviewed and different options are discussed in the scope of a deep geothermal hot dry rock project. While previous works conclude that technologies developed for oil and gas are readily available and applicable to deep geothermal projects and EGS (Gradl, 2018), this study shows that shortcomings exist and that further developments are necessary to reliably and economically complete EGS projects. The necessary tests before running different parts is also discussed. Other options for reservoir creation are debated with their potential benefits and associated risks. The developments that could make them work in an EGS project are discussed.
Insight into Hydraulic Fracture Geometries Using Fracture Modeling Honoring Field Data Measurements and Post-Fracture Production
Authors: Stegent Neil , Dusterhoft Ron , Menon Hari 
Published: April 2019

Abstract
Using planar fracture models to match treatment pressure and improve understanding of the fracture geometry generation is not a new concept. Knowledge gained from this exercise has historically been used to improve engineered fracture completions and production, and maximize net present value (NPV); however, at some point during the progression from vertical to horizontal wellbores, many within the industry have forgotten about the learnings that can still be gained from current fracture models. Engineered completions have been largely replaced by spreadsheet efficiencies relevant to operations rather than production in too many cases. Some images of unconventional well stimulation treatments portray fractures growing in every direction, forming patterns that resemble shattered windshields, and have often excluded the known physics related to rock geomechanics, reservoir properties, and geology. Excuses to dismiss modeling are numerous and are gaining the reasoning of conformists.
Unconventional resource plays might or might not contain large numbers of natural fractures; but, current fracture models can still be used to gain insight into the fracture geometries being generated. While the development of complex fracture models continues to evolve, the industry can still gain insight to fracture geometry and resulting production using current planar fracture modeling. Caveats to this process are that it requires: Valid measured data to establish model constraints.The engineer to understand the basic physics of how fractures are generated and when (and when not) to twist the "knobs" in the model.The engineer to understand which "knobs" should be used based on real diagnostics information.The actual single well production to be an integral part of the process.
This paper demonstrates the results of honoring data measurements from a multitude of potential sources, including downhole microseismic data, downhole deformation tiltmeters, offset pressure monitoring, DTS, DAS, diagnostic fracture injection test (DFIT) analysis, injection as well as production data with bottomhole pressure measurements, etc., and the resulting observations and conclusions. Several industry examples are discussed to help frame the vast amount of information possible to help engineers do a better job of including more diagnostics into routine operations to provide additional insight and ultimately result in improved models and completion designs.
This paper is not intended to merely demonstrate the results of the work but to spark an interest in bringing more intense engineering back to fracture stimulation modeling for horizontal completions.
Impact of Upscaling on Numerical Estimation of Polymer Increments
Authors: Bourgeois Marcel J. , Hild Jean-Claude , Bursaux Romain T. 
Published: April 2019

Abstract
Two upscaling exercises performed in 2013-14 and 2017-18 on two onshore green fields with conventional to viscous oil are presented, for which the upscaling tried to compensate the effects of grid coarsening, in particular the increase of numerical dispersion and the decrease of heterogeneity. Our methodology was to adjust the water/oil relative permeabilities called pseudo KRs in the coarse scale simulation, in order to reproduce the behavior in terms of pressure, rates, saturations and concentrations of the fine scale model, which was using microscopic rock KRs based on laboratory data.
As the upscaling depends on the fluid injected, it was done separately for waterflood and polymer flood. When done with polymer flood, the concentration of polymer had to be history matched also mainly by adjusting the Todd-Longstaff mixing parameter in addition to the KRs. As upscaling is case dependent, it was performed on several geological models, varying heterogeneity and grid size, but also rock KRs and even precocity of the polymer flood after some waterflood, to test the robustness of the approach.
It was found that pseudo-KRs for waterflood could be slightly degraded for viscous oils, whereas the upscaling was more neutral for conventional oils. This correlates well with field observation for viscous oils, where water production occurs generally a bit quicker than what numerical simulation predicts when using rock KRs, in absence of upscaling.
For polymer floods, which were considered in secondary or early tertiary mode, pseudo KRs were generally improved, mainly because the polymer steepened the saturation fronts, which can be well represented only with small lateral grid size.
The result of both upscaling exercises was that the increment of polymer flood versus waterflood was noticeably higher when computed on high resolution modelling. This is equivalent to saying that when using pseudo KRs resulting from this high resolution matching, the polymer increment on coarse grid is significantly higher than if computed without pseudo KRs. This improves the economic evaluation of the project, increasing the willingness to de-risk and implement early polymer floods on these fields.
Application of MCMC Optimization Method to Estimate Relative Permeability of Carbonate Rocks from Unsteady-State Core Flood Experiments
Authors: Da Silva Moreira Paulo Henrique , Gomes da Silveira Thaís Márcia , Drexler Santiago , Couto Paulo 
Published: April 2019

Abstract
The reliable prediction of reservoir performance requires the cost effective implementation of oil recovery systems, and it is necessary to simulate the fluid flow processes in the reservoir and to measure the rock and fluid properties that determine reservoir behaviour. However, a good prediction relies on accurate values of reservoir physical properties. Carbonates rocks in Brazilian Pre-salt are known for their heterogeneity. Characterizing their physical represents a great challenge and the combination of experimental and computational techniques lead to a more comprehensive understanding of the reservoir behavior.
In the present work, the relative permeability curves of a carbonate core sample with respect to oil and water are calculated by matching the data obtained in a labscale unsteady-state core flood experiment carried out at high pressure high temperature characteristics of Brazilian Pre-salt reservoirs. Corey-type equations were used to model the relative permeability due to its simplicity and having fewer parameters involved. The Monte Carlo Markov chain (MCMC) method was used as optimization tool, taking the fluid production and pressure drop measurements collected during the core flood experiment as input data. An alalysis of the sensitivity cofficients was carried out in order to deal with eventual linear dependences among the terms to be estimated. The Markov chain was generated and its convergence observed. The posterior distributions of the constant terms in the Corey equations were calculated and their mean values applied in order to calculate the relative permeability curves for the oil and water phases. The range of water saturation in which the relative permeability curves describe the core conditions after the breakthrough time, due to the occurrence of capillary end-effects, was calculated. The history match of fluid production and pressure drop was carried out, showing a good fit between the pressure curves. A gap was observed between the production curves due to the fact that the experimental measurements accounted the cumulative volume of oil and water, while the theoretical curve accounted the oil volume only.
Groundwater treatment by ceramic membranes: pilot tests at the Commonwealth Games Village in Delhi, India
Authors: Pillai S. B. , Walder C. , Gupta P. , Koganti Y. P. , Lahnsteiner J. 
Published: April 2019

Abstract
Ceramic membranes are increasingly gaining popularity in the field of water treatment. High quality, better operability, robustness, ability to work in harsher environments and efficient removal of organic contaminants are just some of the characteristics which are making it an interesting alternative for water treatment facilities worldwide. This paper aims to evaluate the performance of an ultrafiltration (UF) ceramic membrane pilot plant installed in an 1 MGD (million gallons per day) plant in Delhi, to adapt the process and to optimize the operational features, so that it can be suggested as an economical and technical alternative to existing UF polymeric membrane installations in Indian municipal facilities. The investigation is conceptualized with the production of potable water after filtration at a volumetric flow rate of 1.2 m3/h through an UF ceramic membrane having a pore size of 50 nm. The process parameters such as the duration of filtration, flow rate, flux, flocculant concentration, and chemicals were varied to check its adaptability and effectiveness for better performance. Laboratory tests, evaluation of the results and troubleshooting were used to regulate the quality aspects of the study.
The Interaction of Zinc Oxide/Green Tea Extract Complex Nanoparticles and its Effect on Monosodium Glutamate Toxicity in Liver of Rats
Authors: Al-Salmi Fawziah A. , Hamza Reham Z. , El-Shenawy Nahla S. 
Published: April 2019

Background:Zinc oxide nanoparticles (ZnO NPs) are increasingly utilized in both industrial and medical applications. Therefore, the study was aimed to investigate the effect of green nanoparticle complex (green tea extract/zinc oxide nanoparticles complex, GTE/ZnO NPs) on oxidative stress induced by monosodium glutamate (MSG) on the liver of rats.Methods:Wistar male rats (n=64) weighing between 200-250 g were divided randomly into eight groups: control group was given physiological saline (1 mg/kg), two groups were treated with two different doses of MSG (MSG-LD, MSG-HD; 6 and 17.5 mg/Kg, respectively), GTE was given 1 mg/mL, 5th group was treated with ZnO NPs and 6th group was treated with GTE/ZnO NPs complex while, 7th and 8th groups were treated with MSG-LD + GTE/ZnO NPs complex and MSG-HD + GTE/ZnO NPs complex, respectively. All substances were given orally for 30 consecutive days. At the end of the study, the liver was homogenized for measurement of the oxidative stress status and anti-inflammatory biomarkers as well as histological and transmission alternations.Results:Results showed that the antioxidant enzymes activity and glutathione level were significantly decreased in MSG groups than control in a dose-dependent manner. Conversely, the malondialdehyde and inflammatory cytokines levels were significantly increased in MSG groups than the control group. The liver indicated no evidence of alteration in oxidative status, anti-inflammatory and morphological parameters in GTE, ZnO NPs and GTE/ZnO NPs complex groups.Conclusion:In conclusion, MSG at both doses caused oxidative stress and inflammation on liver after 28 days of exposure that supported histological analysis and transmission view of hepatic parenchyma. GTE/ZnO NPs act as partial hepato-protective against MSG.
Anti-TNF and Postoperative Complications in Abdominal Crohn's Disease Surgery
Authors: Yamamoto Takayuki , Teixeira Fabio Vieira , Saad-Hossne Rogerio , Kotze Paulo Gustavo , Danese Silvio 
Published: April 2019

Background: :
Biological therapy with anti-Tumour Necrosis Factor (TNF)-α agents
revolutionised the treatment of inflammatory bowel disease over the last decades. However,
there may be an increased risk of postoperative complications in Crohn’s disease (CD) patients
treated with anti-TNF-α agents prior to abdominal surgery.

Objective::
To evaluate the effects of preoperative anti-TNF-α therapy on the incidence of complications
after surgery.

Methods: :
A critical assessment of the results of clinical trial outcomes and meta-analyses on the
available data was conducted.

Results: :
Based on the outcomes of previous reports including meta-analyses, preoperative use of anti-
TNF-α agents modestly increased the risk of overall complications and particularly infectious
complications after abdominal surgery for CD. Nevertheless, previous studies have several limitations.
The majority of them were retrospective research with heterogeneous outcome measures and
single centre trials with relatively small sample size. In retrospective studies, the standard protocol
for assessing various types of postoperative complications was not used. The most serious limitation
of the previous studies was that multiple confounding factors such as malnutrition, use of
corticosteroids, and preoperative sepsis were not taken into consideration.

Conclusion::
Among patients treated with preoperative anti-TNF-α therapy, the risk of overall complications
and infectious complications may slightly increase after abdominal surgery for CD.
Nevertheless, the previous reports reviewed in this study suffered from limitations. To rigorously
evaluate the risk of anti-TNF-α therapy prior to surgery, large prospective studies with standardised
criteria for assessing surgical complications and with proper adjustment for confounding
variables are warranted.