bluuebunny/crossref_metadata_2025_split huggingface dataset:
Machine Learning Optimizes Duvernay Shale-Well Performance
Authors: Feder Judy 
Published: May 2019

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 189823, “Machine Learning Applied To Optimize Duvernay Well Performance,” by Braden Bowie, SPE, Apache, prepared for the 2018 SPE Canada Unconventional Resources Conference, Calgary, 13–14 March. The paper has not been peer reviewed.
This paper discusses how machine learning by use of multiple linear regression and a neural network was used to optimize completions and well designs in the Duvernay shale. The methodology revealed solutions that could save more than $1 million per well and potentially deliver an improvement in well performance of greater than 50%. The work flow described rigorously analyzes the relationships between a significant number of well-completion variables, predicts results, and performs optimizations for ideal outcomes. The work flow is not Duvernay-specific and can be applied to other basins and formations.
Introduction
A fundamental problem for machine learning in many industries is that a responding variable is controlled not by one but by a number of predictor variables. Inferring the relationship between the responding variable and the predictor variables is of key importance. Interactions between predictor variables and noise in the data complicate matters further. This problem can be solved with multiple linear regression or a neural network, both of which use all of the predictor variables together. However, care must be taken to obtain a model that is truly predictive and not merely a result of overfitting the data.
In unconventional oil and gas reservoirs, well performance generally is characterized either at the well level by detailed technical work such as rate-transient analysis, microseismic, and other techniques or at the field level by statistical methods with ranges for production performance. Refinement of this statistical interpretation generally involves normalizing for only one or two key parameters, such as lateral length or tonnage. Additionally, wells usually are grouped or excluded entirely from the population for various reasons, such as substandard completion design. This introduces bias in the selected wells and reduces the sample size. As a result, this approach is limited to the key variables identified and the bias introduced by the well population selected.
The idea of using a neural network has been executed successfully in the past to optimize completions. However, data sets were limited. Recently, the use of machine learning has grown substantially by integrating more variables in the analysis, which reduces reservoir uncertainty.
The goal of the work flow described in the complete paper is to improve on previous methodology by rigorously and statistically refining estimates for well performance without excluding wells and to recommend which variables are and are not influencing well performance. The goal was accomplished through machine learning in the form of a multiple linear regression and a neural network, comparing the results from both.
Technology Focus: Multilateral and Complex-Trajectory Wells (May 2019)
Authors: Aadnøy Bernt S. 
Published: May 2019

Technology Focus
When students ask me about the most important way to maximize recovery, my answer is long directional wells. These wells have revolutionized the oil industry and are drilled under conditions never imaginable years ago. One outstanding example is the Troll field in Norway. The field consists of large, very thin reservoirs, down to 30 ft thick, which are drained by multibranch horizontal wells with horizontal departures approaching 18,000 ft. Not only have many drilling challenges been overcome, but also, from a production perspective, the wells are equipped with intelligent technology such as autonomous gas stop to maintain the pressure drive for the oil. Initially of no commercial interest because of a lack of technology, this field has been a very important driver for the current state of the art for long horizontal wells. Troll has been Norway’s largest oil producer in recent years. This has been made possible by the development of long-horizontal-well technology.
The oil industry is currently undergoing a technological transformation that will add value, improve processes, and reduce cost. Future drilling engineers will have knowledge of robotics, automation, and organizational efficiency, which is highly appealing for recruitment. A prerequisite for this step change is the industry’s high level of technology.
The selected papers address various aspects of horizontal wells. A field case of how to plan and drill through highly depleted reservoirs is given in paper OTC 28517. Three depleted zones must be penetrated before drilling into the untapped reservoir with a low drilling margin. This is a good example of drilling an extended-reach well using an integrated approach between various disciplines. Another example is given in paper SPE 191436, which shows how a complex U-shaped well path from old wells can be used to obtain good reservoir exposure to drain depleted wells further. Equipment is continuously improved, and paper SPE 189947 presents new ultrasonic technology to evaluate the state of multilateral junctions.
SPE 191271 Extended-Reach Wells in Unconsolidated Sands in Bolivia by Gabriel Dordoni, Pluspetrol Bolivia
OTC 28971 Correlation of Numerical Simulation and Digital-Image-Correlation Strain Measurements for a Multilateral Junction While Subjected to High Internal Pressure by Aihua Liang, Halliburton, et al.
SPE 192672 Wireline Tractor Conveyance—A Technology Game Changer for the Gulf of Thailand by Sarunya Jongnarungsin, Mubadala Petroleum, et al.
Technology Focus: Cementing and Zonal Isolation (May 2019)
Authors: DeBruijn Gunnar 
Published: May 2019

Technology Focus
Cementing and zonal isolation are critical through the life cycle of the well. As I read through the cementing papers that were presented this year, I observed discussions on cementing and zonal isolation during drilling, completion, and abandonment activities.
I am encouraged that we, as an industry, continue to refine and tweak our practices to solve zonal-isolation and cementing challenges in every well environment in which we work. Numerous papers not included here target improving cementing applications. Discussions about the mitigation of losses, low-density slurries, foam-cement slurries, spacer design, centralizer programs, expanding agents, flexible cement, and the management of narrow pressure margins are spread throughout SPE conferences. As cementing techniques are improved, so, too, are the cement-evaluation methods and work flows. The proof of zonal isolation is important to many, including resource owners, operators, regulators, land owners, and other stakeholders.
As we drill longer extended-reach and horizontal wells, we continue the quest for zonal isolation using new technologies. Paper SPE 191561 discusses the mitigation of mud channels in horizontal wells drilled with nonaqueous drilling fluids. Academia has been experimenting and investigating placement practices. Recommended additional reading paper SPE 191989 explores the balance of buoyancy and eccentricity in both regular and irregular geometries.
Another technology that is becoming more prevalent is the use of managed-pressure drilling, which leads to the need to understand managed-pressure cementing (MPC). Recommended additional reading paper SPE 191344 provides a case study for the use of MPC in both riserless mud recovery and con-trolled mud level applications.
Abandonment is the final zonal-isolation activity in the well life cycle. The application of alternate materials continues to be discussed in all of our conferences. Paper SPE 193118 demonstrates the use of bismuth and thermite as an abandonment material. Paper SPE 191607 discusses the activation (and proof) of shales for zonal isolation. And finally, recommended additional reading paper SPE 191335 provides insight into the ultimate objective of cement-plug integrity.
Recommended additional reading at OnePetro: www.onepetro.org .
SPE 191989 Displacement Efficiency for Primary Cementing of Washout Sections in Highly Deviated Wells by Alondra Renteria, University of British Columbia, et al.
SPE 191335 Cement Plug Hydraulic Integrity—The Ultimate Objective of Cement Plug Integrity by Axel-Pierre Bois, CURISTEC, et al.
SPE 191344 Experience Using Managed-Pressure Cementing Techniques With Riserless Mud Recovery and Controlled Mud Level in the Barents Sea by E. Claudey, Enhanced Drilling, et al.
SPE 193965 Caprock Restoration in Well Abandonment: Fit-for-Purpose Well-Abandonment Design Through Work Flow Optimization and Integrated Assessment by Jing Zhi Kueh, Petronas, et al.
As Exciting as Watching Scale Grow: Real-Time Observations Generate New Control Ideas
Authors: Rassenfoss Stephen 
Published: May 2019

Anne Neville wants engineers to look at scale buildup differently. A pipe-clogging buildup of calcium carbonate is not simply the product of reactions in a chemical stew found in a hot, pressured space to the professor at the University of Leeds.
The factors controlling how and where scale grows into a problem are also a function of how fast the gas and fluids are moving, whether the flow is smooth or turbulent, and critically, the surface at the edge of the flow.
A rough surface is more likely to allow scale to take hold and an oil coating can limit calcium carbonate scale, as can corrosion competing for surface space. Coatings on the pipe have an effect depending on differences that can be microscopic.
As the director of the Institute of Functional Surfaces at the university’s engineering school, Neville is upfront about an obsession with every little detail related to surfaces, from new steel in the ground to the top of scale growth.
“The word we keep coming back to is surface, surface, surface,” Neville said during the keynote speech at the SPE International Conference on Oilfield Chemistry. Her message at the recent meeting in Galveston, Texas, was that in the future those managing scale growth will consider many more variables.
There is value in classic lab tests designed to measure which crystals form—clear glass jars are filled with water, scale-creating components, and perhaps a chemical designed to inhibit growth.
But other testing will be needed because the environment in a glass jar cannot replicate the effect of all the surfaces that can alter growth in a well.
“When I predict scale I want to know what kind of things make things grow and what things predict how it grows,” Neville said.
To do so, the institute has developed devices to observe and measure the growth of scale crystals as it is happening. High-power magnification and ultrasensitive scales are used to quantify the results.
The institute’s 75 scientists are interested in a range of topics beyond scale on surfaces, including lubrication, developing new coatings, and studying corrosion.
Neville said rust provides a benchmark for the scale study work. While there are rules of thumb to estimate the rate of corrosion, there are no similar formulas for scale.
With flow assurance problems such as calcium carbonate buildup, the answer depends on many variables, including competition from rust for a place on the surface.
Things To Consider
Researchers are looking for answers at institutions around the world. A paper by scientists from the Institute of Functional Surfaces summarizing recent advances in the understanding of scale growth offered three pages of citations.
Much of this work is fundamental research, which commonly is delivered with the warning that further work is likely to complicate early findings.
Rough surfaces encourage scale development, but some are more welcoming than others. Multiple theories have been offered to explain why molecules thrive on irregular surfaces, at least when viewed under magnification.
Sero-epidemiology of rubella in Zambia in the pre-vaccination period (2005 – 2016) as baseline for evaluation of introduction of rubella vaccine into the national immunization program
Authors: Mazaba Mazyanga Lucy , Siziya Seter , Monze Mwaka , Cohen Daniel 
Published: May 2019

Abstract
Background

Rubella is highly under-reported in Zambia as in most sub-Saharan countries despite being a disease of major public health concern especially among women of childbearing age. In September 2016, Zambia introduced a combined measles-rubella vaccine in children aged 0-14 years. In this study, we estimated the rubella sero-prevalence and its correlates between 2005 and 2016, a period prior to the introduction of Measles-Rubella vaccine in Zambia to provide baseline reference data for the future evaluation of its impact.

Methods

In a retrospective study, serum samples collected through the national measles surveillance program that tested negative for measles were examined for rubella IgM antibodies using the Siemens, Enzygnost® ELISA kit at the national measles laboratory accredited by WHO. Data on age, sex, province, year and month of onset were extracted from the surveillance data. Logistics regression analysis was conducted to determine independent predictors of rubella infection.

Results

Overall, a sero-prevalence of 29.2% (1313/4497) affecting mostly those between 5 and 24 years was determined. Logistics regression results indicated that only age, province, year and month were independently associated with rubella infection. The regional sero-prevalence varied from 21.8 – 37.3% peaking in the hot dry month of October. Logistics regression indicated that those in the age group 10-14 years (AOR=2.43; 95% CI [2.01 - 2.95]) were more likely while those aged <1 year less likely (AOR=0.31; 95% CI [021 - 0.48]) to have rubella compared to those aged 25 years or older. Persons in 2010 were less likely (AOR=0.12; CI [0.05, 0.28]) to have rubella infection compared to those in 2016. While rubella infections were more likely to occur between July and November compared to December, they were less likely to occur between February and May.

Conclusions

There is evidence that rubella virus was circulating in Zambia between 2005 and 2016 affecting more females than males and persons in the age group 5-24 years with a peak in the hot dry season. It is recommended that immunisation campaigns be targeted in months of lower virus transmission between February and May and in a situation of limited resources to those aged 5-24 years.
A case of a 49-year-old woman with IgG4 anti-Neurofascin155 antibody-positive CIDP in both serum and cerebrospinal fluid
Authors: He Linlu , Chen Xiu , Lin Huan , Yuan Ping 
Published: May 2019

Abstract
Background CIDP (chronic inflammatory demyelinating polyneuropathy) is an autoimmune disorder of peripheral nervous system, causing demyelination and even axonal degeneration. Recently, anti- Neurofascin155 (NF155) antibody-positive CIDP began to cut a figure. This is a special type of CIDP that progressively worsen and predominantly involving distal limbs. IgG4 anti- NF155 antibody-positive CIDP combining serum with CSF in clinical is very rare. The article displayed the clinical practice to evoke the diagnosis of IgG4 anti- NF155 antibody-positive CIDP in front of the disabling tremor and ataxia. We described a rare clinical disorder of IgG4 anti- NF155 antibody-positive CIDP with reviewing some of literatures. Case presentation A 49-year-old woman presented with an evaluation of weakness, numbness and a little ache of all her limbs for half a year. She revealed ataxia, intention tremor and wide-based gait. Cerebrospinal fluid (CSF) results showed the noticeably elevated protein level without pleocytosis. The findings of peripheral nerve conduction（NCV）indicated marked prolongation of distal and F-wave latencies which conformed to demyelinating polyneuropathy. And her spinal MRI illustrated a thickened right nerve root of sacrum 1-2. IgG4 NF155 antibodies of serum together with CSF were positive by indirect immunofluorescence based on NF155 transfection cells. A high-dosage mythylprednisolone pulse followed by oral prednisolone improved her symptoms. Conclusion Disabling tremor, ataxia, younger onset age, high protein levels in CSF, marked prolongation of distal and F-wave latencies, the roots or plexus of neck and lumbosacral nerves thickening on MRI, and poor response to IVIg may consider as biomarkers of IgG4 anti- NF155 antibody-positive CIDP.
Switchgrass Forage Yield and Compositional Response to Phosphorus and Potassium
Authors: Ashworth A. J. , Moore P. A. , King R. , Pote D. H. , Douglas J. L. , Jacobs A. A. , Pratt E. 
Published: May 2019

Core Ideas
Recommended P and K rates are largely unknown for native grasslands.
Switchgrass requires low levels of P and K in a two‐cut forage system.
There are limited forage quality gains from P and K fertilizers.
Nitrogen is a more limiting nutrient in switchgrass forage systems on marginal soils.
Finite nutrients, including P and K, are required in large quantities for many warm‐season forages. However, native perennial grasses such as switchgrass (Panicum virgatum L.) have less of an affinity for fertilizers, although recommended P and K rates are largely unknown. Objectives were to test switchgrass forage yield response to P and K rates representative of warm‐season forages and identify compositional impacts for developing switchgrass forage fertilizer recommendations. Switchgrass cv. Alamo was subjected to two harvests per year after applications of 0, 28, 56, 112, and 224 kg P ha−1, and split applications of 0, 134, 269, 404, and 538 kg K ha−1 yr−1, from 2014 to 2016. Two sets of controls were used, a “nutrient control” (0 P and K with supplemental rates of N and S) and a “control” (no fertilizer). Harvest timing (first or second cuts) did not influence (P ≥ 0.05) P or K removal or forage yields. For all study years, the control (no supplemental fertilizer) resulted in substantially lower (P ≤ 0.05) yields than the nutrient control, meaning yield did benefit (44 and 49% increases) from supplemental nutrient applications. Therefore, minimal P and K inputs are required for a yield response, as there were very few detectable yield increases beyond the lowest tested application rates (134 kg K ha−1 and 28 kg P ha−1). Results indicate P and K are required in low amounts and that N is a more limiting nutrient in switchgrass forage systems on marginal soils of the southeast.
Short‐Term Improvement in Soil Physical Properties of Cultivated Histosols through Deep‐Rooted Crop Rotation and Subsoiling
Authors: Thériault Laura , Dessureault‐Rompré Jacynthe , Caron Jean 
Published: May 2019

Core Ideas
Short rotations showed small hydraulic conductivity improvement the year of rotation.Effects vanished the year after termination of the rotational crops.Pore continuity appears to be disrupted by tillage operations.
The formation of a compacted layer in cultivated organic soils reduces water infiltration and can lead to the formation of a perched water table. To test the hypothesis that integrating deep‐rooted crops in a short‐term rotation could improve soil physical properties, a 3‐yr trial was conducted on two Histosols. A lettuce (Lactuca sativa L.) control and three crops combinations—corn (Zea mays L.) and common vetch (Vicia sativa L.), sorghum [Sorghum bicolor (L.) Moench] and faba bean (Vicia faba L.), and a mix of tillage radish (Raphanus sativus L.), ryegrass (Lolium perenne L.) and crimson clover (Trifolium incarnatum L.)—were planted for 2 yr, on subsoiled and not subsoiled plots. Then, lettuce was reintroduced on all plots the third year of the experiment. Measurements of soil penetration resistance (SPR), saturated hydraulic conductivity (Ks and Kfs), water table level, and matric potential were performed over time. Kfs improved in the compacted layer during the second year of the rotation compared with the lettuce control. Subsoiling improved SPR, Ks, and Kfs in some cases. Once tillage was used to reestablish lettuce in the third year, those effects disappeared quickly (<3 mo), likely due to tillage. No treatment differences in water table levels or soil matric potentials were observed at that time, indicating that the short‐term increase in Kfs did not improve deep drainage. Despite short‐term changes in the top horizons, the general drainage pattern was controlled mainly by the deeper organic layers rather than the shallow compacted layer originally identified.
Corn Era Hybrid Nutrient Concentration and Accumulation of Secondary and Micronutrients
Authors: Woli Krishna P. , Sawyer John E. , Boyer Matthew J. , Abendroth Lori J. , Elmore Roger W. 
Published: May 2019

Core Ideas
We compared 1960‐ and 2000‐era hybrid secondary and micronutrient accumulation and partitioning.Nutrient concentrations were mostly lower for 2000‐ than 1960‐era hybrids.Whole plant and fraction nutrient content were generally greater for 2000‐era hybrids.Greater nutrient content in modern hybrids was driven by increased overall plant growth.
Studies are limited that focus on change in concentration and accumulation of secondary and micronutrients in corn (Zea mays L.) plant fractions and across corn hybrid development periods. This research was conducted in 2007 and 2008 to evaluate the partitioning of secondary and micronutrients across vegetative and reproductive stages at the plant‐fraction level for 1960‐ and 2000‐era hybrids. Two popular hybrids for each era were grown, with measurement of nutrient concentration and content in several plant and grain fractions. Secondary and micronutrient concentrations in plant fractions were lower in 2000‐ than 1960‐era hybrids with most nutrients, except ear shoots and tassels for certain nutrients. However, nutrient content was consistently greater in 2000‐ compared to 1960‐era hybrids in the whole plant and fractions at most development stages, except tassels and ear shoots. In tassels, nutrient content was mostly smaller in 2000‐era hybrids, but in ear shoots content was similar. The accumulation rates of most nutrients per growing degree day (GDD) were greater in the reproductive period for 2000‐era hybrids, but similar among eras in the vegetative period. Remobilized nutrients from vegetative to reproductive components were similar between era hybrids, except Ca and Fe, and positive except Fe, Mn, and B. It is apparent that greater nutrient content in newer hybrids was driven mainly by associated nutrient uptake rates and greater dry matter (DM). Despite the greater nutrient content with the modern hybrids, removal with grain or stover harvest would still be small for S and micronutrients.