bluuebunny/crossref_metadata_2025 huggingface dataset:
Atlantis: a Grain of Truth Behind the Fiction?
Authors: Rapisarda Massimo
Published: October 2018

The legend of Atlantis was almost certainly invented by Plato to promote the political ideal of his masterwork The Republic, while praising the heroism of his own ancestors. This paper suggests that, in assembling the story, Plato might have reworked the myth of the foundation of Egypt, attributed to divine invaders bringing agriculture and unknown technologies to the country. The key issue explored is the curious coincidence between the period of the alleged foundation of Egypt (according to traditional Egyptian sources) and some remarkable events that characterized the end of the Ice Age. Indeed, besides the sudden increase in temperature and the consequent rise in sea level, the period was also marked by the birth of agriculture and the appearance of totally new technologies in diverse Middle Eastern locations. The memory of these events would have been handed down through the myth of the foundation of Egypt and, through this, to Greek culture, enabling Plato to exaggerate the antiquity of his noble ancestors while embellishing the characteristics of the invaders. Such occasional technological leaps may also have occurred elsewhere in the world, for instance on the deltas of the Indus or the Yangtze, driven by the same change in climate that affected the whole planet. Although today there is no archaeological evidence of such events besides in the Middle East, the article suggests that the possible discovery of obsidian in a submerged site would be a strong indication of a local technological leap. To this end it examines, amongst suspected Mediterranean sites, some flooded islands in the Strait of Sicily, which, lying on the route to Pantelleria, may retain traces of ancient obsidian exploitation.
Solving the AI Race: Addressing the potential pitfalls of competition towards Artificial General Intelligence
Authors: Schmidt Thomas
Published: October 2018

AGI could arise within the next decades, promising a decisive strategic advantage. This paper discusses risks, associated with the development of AGI: destabilizing effects on strategic balance, underestimating risks in the interest of victory in the race, egoistically exploiting the huge benefits by a tiny minority. Further: Developed AGI could be beyond human control. Human goals could not be implemented and an intelligence explosion to superintelligence could take place leading to a total loss of control and power. If competition for AGI is non-transparent, secret, uncontrolled and not regulated, it’s possible that risks could not be managed and would lead to catastrophic consequences. The danger corresponds to that of nuclear weapons. It is crucial that the key actors of a possible AI Race agree at an early stage on the prevention and transparent regulation of a possible AI Race - similar to measures to secure strategic stability, on arms control measures, disarmament, and prevention of the proliferation of nuclear weapons. The realization that an uncontrolled AI race can lead to the extinction of humanity - this time even independent of human will – requires analogous measures to contain, prevent, regulate and secure an AI race within the framework of AGI development.
The Riemann Spring
Authors: Sun Bohua
Published: October 2018

This paper attempts to propose a Riemann spring model via an analogy between the Riemann Zeta function of a complex number and the elastic spring in series.
Effect of 3-Month Lysine Supplementation on Growth and Muscle Function Parameters in Pre-pubertal Indian Girls
Authors: Verghese Sejil T. , Pauline Maria , Das Arun , Kurpad Anura V.
Published: October 2018

Lysine is the limiting amino acid in the predominantly cereal and legume based typical Indian diet and its supplementation has been shown to positively affect muscle strength in short term adult and animal models; but similar studies are lacking in children. This study looked at the effect of a 3-month lysine and iron intervention on muscle strength and growth parameters in prepubertal Indian girls. The study was a randomized controlled trial conducted in 40 normal Indian girls in the 9-10 yrs age group. The control group received only iron (6.25mg) supplementation, while the intervention group received both iron and lysine supplementation that increased the lysine intake to 50mg/kg/day. Muscle strength was estimated in both upper limbs with a hand dynamometer and muscle endurance was estimated in the non-dominant hand. Height and weight were recorded to assess growth. A significant difference was seen in the increase in the non-dominant hand grip strength between the groups (intervention: 1.4 vs control: 0.2 kg, p=0.042) at the end of the study. There was a trend of increased height gain (about 25%) and weight gain (about 50%) in the intervention group compared to control group. Lysine supplementation for 3 months increased non-dominant forearm muscle strength in Indian children.
A Review on Regulatory Aspects of Food Contact Materials (FCM’S)
Authors: Deepika Rani V. S. , Naveen Kumar R. , Vemula Sudershan Rao
Published: October 2018

Since the advent of commercial production of Food Contact Materials (FCM) and their extensive use in day to day life, many harmful effects on health were reported to be caused due to ingestion of food contaminated with constituents that migrated from FCM. Over the years, this aspect of food safety from FCM rose to be an important research interest and thus added scientific information on FCM. Based on the scientific evidence and new issues being raised (E.g. BPA replaced by other substances), these regulations are also being molded from time to time across the world. Therefore this review aims at providing an overview of regulations and amendments on FCM in various countries with emphasis on important aspects (e.g. traceability and safeguard measures of EU framework regulations, Food contact notification of USFDA, etc.) in FCM laws. Hereunder, for a better understanding of these regulations, various countries reviewed in this article are grouped into 3 categories, i.e. – countries having 1) specific regulations 2) Non- specific/ few regulations 3) No data available on FCM regulations. Though these regulations differed from one country to other, all were formulated with a primary objective, of ensuring consumer food safety. This review will not only help in ensuring food safety but also helps in, to strengthen regulatory framework and grow in trade, fulfilling the gaps with global FCM regulations.
Modern Methods of Creating Casting Model Kits
Authors: Kalinichenko M. L. , Dolgiy L. P. , Rovin S. L. , Kukareko V. A. , Kalinichenko U. A.
Published: October 2018

The article presents some information about creation of model kits and core equipment for the manufacture of molds and rods of cold-hardening sand-clay mixtures in the individual, serial and mass production of castings of ferrous and non-ferrous metals. There was analyzed their constituent materials and investigated a number of mechanical properties of the binding components for their attachment. Was shown the analysis of adhesive compositions of the world’s leading manufacturers, used for the manufacture of high-strength model sets by 3D milling methods.
Extraction from aqueous solutions ions of iron and lead by filter loading, created on the basis of steel melting slag
Authors: Panasyugin A. S. , Grigor’ev S. V. , Teran A. I. , Anufriev V. N. , Tsyganov A. R. , Masherova N. P.
Published: October 2018

The aim of the present paper is investigation of removal of Fe3+ and Pb2+ ions from aqueous media by material on the basis of steel melting slag. It has been established that the process of water purification from Fe3+ and Pb2+ ions by this material proceeds by a mixed mechanism both due to the formation of slightly soluble silicates and also due to the formation of hydroxides. When the filtration rate varies from 2 to 10 column volumes per hour, the percentage of sorption remains within 91,5–99,8%. The most optimal filtration rate is 6 column volumes per hour. Material on the basis of steel melting slag absorbs of Fe (III) up to 5 mg-eq/g and Pb (II) 0.64–1.27 mg-eq/g.
Comments: The Inevitable Price Cycle
Authors: Donnelly John
Published: October 2018

Editor's column

Russian President Vladimir Putin and Saudi Crown Prince Mohammed bin Salman met in mid-June on the sidelines of a World Cup game in Moscow to discuss oil prices and diplomacy ahead of the recent OPEC meeting. It was the latest effort to wrest control of oil prices that began with the historic Vienna production cuts in 2016 that rescued the oil market, and the most recent in a long line of attempts to control the oil price cycle.

The production cuts worked. The OPEC members and several largest producers, including Russia and Mexico, agreed in late 2016 to curb oil production by 1.8 million B/D to reduce the supply glut that had sent prices plummeting and caused massive layoffs throughout the industry. Compliance was not only good, but better than expected. Some countries cut supply even more than they agreed, and Venezuelan output dropped sharply because of that country’s economic crisis, which brought the market back in balance. The production cuts totaled almost 2.5 million B/D, according to the International Energy Agency (IEA).

The extent of the cuts has led some, including the IEA, to fear that the market could soon be in short supply, sending prices sharply higher, and continuing the cycle of sharp shocks to the market. To them, oil prices in the $60–70 bbl range would be ideal, encouraging new production to replace declining reserves without disrupting demand growth. The oil market has tightened quickly, which should lead to output increases from major producers this year and next.

Common phrases in the industry this year are “cautious optimism” about prices and “capital discipline.” But oil price cyclicality appears inevitable. The long-term nature of the business that requires years to develop new production, along with reliance on lagging indicators and the relative price inelasticity of consumption, underlies the difficulty of balancing supply and demand. Since 2014, rebalancing the oil market has meant cutting production and reducing inventories; for the rest of this year and 2019, it will mean increasing supply to prevent prices from rising too quickly.

One source of supply that may help is the Permian Basin, which has seen remarkable growth during the downturn, and could act as a swing producer and a major oil exporter. A new report from IHS Markit forecasts that Permian production will rise by almost 3 million B/D to 5.4 million B/D by 2023. Production from the Permian by itself would be greater than any OPEC country except Saudi Arabia and the additional output would be more than the production of Kuwait, the report said. Permian output was less than 1 million B/D in 2010. One thing that could derail this predicted increase is strains on infrastructure. Already, logistical bottlenecks in pipelines and trucking have occurred, causing some production to be deferred to next year.
The UK North Sea: How To Manage an Aging Basin
Authors: Whitfield Stephen
Published: October 2018

The words “UK North Sea” do not engender much more than cautious optimism these days when talking about oil and gas production, with dropping production and high decommissioning costs dominating the conversation.

The reality is more complicated. After 14 years straight of production declines, and particularly sharp production declines from 2010 to 2014, the UK continental shelf (UKCS) saw production increases from 2015 to 2017. While it is a mature basin in the midst of overall decline, the UKCS has shown potential. Production in recent years has been boosted by a number of large projects coming online such as BP’s Schiehallion and Chevron’s Rosebank. Future production numbers may see a boost from discoveries like BP’s Capercaillie and Achmelvich, and Hurricane Energy’s discoveries at Halifax and Lincoln in the West of Shetland area. Companies and government regulators also see opportunities.

Whether those opportunities will lead to anything beyond a temporary reprieve remains a question. Even if the decline resumes next year, as some have forecast, managing the assets still active in a way that avoids double digit losses will be a challenge for all the stakeholders in the area.

The Value of Infrastructure

In discussing decommissioning and abandonment’s place in the North Sea conversation, Oil and Gas UK economics and market intelligence manager Adam Davey said he has seen little evidence of a massive pickup in activity, with more stories coming about operators trying to extend field life and defer decommissioning.

However, the massive cost of decommissioning is still the most pressing issue facing companies operating in the region. The North Sea makes up the majority of global offshore decommissioning costs, and while the region is forecast to comprise a smaller share of the global total over the next 4 years, the overall costs of North Sea decommissioning should still rise from 2018 to 2021 (Fig. 1). Wood Mackenzie predicted that decommissioning spend will overtake capital expenditure by 2022.

In the UK, decommissioning costs are expected to remain consistent at $2.3 to $2.7 billion annually over the next 5 years, compared to $532 million to $1 billion on the Norwegian continental shelf and $864 million to $1 billion on the Dutch continental shelf. Oil and Gas UK said it is an indication that there is no need to rush decommissioning efforts.

While decommissioning activity on the UKCS is much greater than in the other sectors on the North Sea, the consultancy said this reflects the total amount of infrastructure in the basin, as well as the fact that an increasing number of mature assets are naturally reaching the end of their productive lives. Wood Mackenzie said it is not necessarily an indicator that the UKCS is entering a steep decline.
Integrated CO2-Foam Pilot in a Heterogeneous Carbonate Field
Authors: Carpenter Chris
Published: October 2018

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 190204, “An Integrated CO2 Foam EOR Pilot Program With Combined CCUS in an Onshore Texas Heterogeneous Carbonate Field,” by Z.P. Alcorn, SPE, and S.B. Frederiksen, University of Bergen; M. Sharma, University of Stavanger; A.U. Rognmo, SPE, University of Bergen; T.L. Føyen, SPE, University of Bergen and SINTEF; and M.A. Fernø, SPE, and A. Graue, SPE, University of Bergen, prepared for the 2018 SPE Improved Oil Recovery Conference, Tulsa, 14–18 April. The paper has not been peer reviewed.

A carbon-dioxide (CO2) -foam enhanced-oil-recovery (EOR) pilot research program has been initiated to advance the technology of CO2 foam for mobility control in a heterogeneous carbonate reservoir. Previous field tests with CO2 foam report varying results because of injectivity problems and the difficulty of attributing fluid displacement specifically to CO2 foam. A more-integrated multiscale methodology was required for project design to further understand the connection between laboratory- and field-scale displacement mechanisms.

East Seminole Field

The East Seminole Field in the Permian Basin of West Texas was discovered in the early 1940s with an estimated 38 million barrels of original oil in place (OOIP). The field was developed throughout the 1960s, producing 12% OOIP through pressure depletion. Water floods began in the early 1970s and continued into the 1980s with strategic infill drilling, reducing the well spacing from 40 to 20 acres.

Tertiary CO2 floods began in inverted 40-acre, five-spot patterns in 2013 in the eastern portion of the field. Miscible CO2 injection initially increased oil production and reservoir pressure. However, rapid CO2 breakthrough, high producing gas/oil ratio (GOR), and CO2 channeling was soon observed in peripheral production wells. CO2 performance suffers because of reservoir heterogeneity and unfavorable mobility ratios between injected CO2 and reservoir fluids, resulting in poor areal sweep efficiency, high producing GOR, and CO2 channeling.

As seen in other areas of the Permian Basin, tilted fluid contacts, presumably resulting from basin activity or a breach of seal, have created a deeper residual oil zone (ROZ). These zones are thought to have been naturally waterflooded through hydrodynamic dis-placement and have been shown to contain considerable immobile oil (20 to 40% OOIP) that can be mobilized by CO2 flood. Thus, the residual oil saturation in the ROZ is similar to waterflooded zones and establishes it as an economically attractive target for tertiary CO2 recovery efforts.
Artificial Intelligence and Robotics Support Marine Mining
Authors: Carpenter Chris
Published: October 2018

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29069, “How AI and Robotics Can Support Marine Mining,” by Peter Kampman, Leif Christensen, Martin Fritsche, Christopher Gaudig, Hendrik Hanff, and Marc Hildrebrandt, German Research Center for Artificial Intelligence (DFKI), and Frank Kirchner, DFKI and University of Bremen, prepared for the 2018 Offshore Technology Conference, Houston, 30 April–4 May. The paper has not been peer reviewed. Copyright 2018 Offshore Technology Conference. Reproduced by permission.

Marine mining initiatives open a new field of subsea operations. Offshore oil and gas sites are still located primarily in areas where divers can support maintenance and repair requirements, but future marine mining will take place in greater depths and with a complexity of machines that requires support from robotic systems equipped with a substantial amount of artificial intelligence (AI). Technologies are being developed that have the potential to support marine mining in all stages from prospection to decommissioning. These developments will likely have substantial influence in the oil and gas industry, itself searching for ways to maximize exploitation of assets.

Robotic Systems

Under Current Development Increasing Autonomous Underwater Vehicle (AUV) Intelligence. Commercial off-the-shelf AUVs rely mostly on acoustic and inertial sensors for their navigation. Speed measurements from a Doppler velocity log are combined with orientation values from gyroscopes and accelerometers to estimate current position. These updates are sometimes augmented by absolute-position fixes from an ultrashort baseline system. However, during such a mission, the inspection assets might not be located exactly at their expected positions. This might be because of incorrect positioning during installation, objects being dragged off location by fishermen, or sediments hiding a pipeline gradually from the view of standard sensors. Therefore, equipping modern AUVs with sensors and software that can search for, detect, track, and re acquire inspection targets is essential.

In addition, classical sensor suites consisting of cameras and sonars can be augmented with higher-resolution 3D sensing such as laser-line projectors (structured light). This enables an AUV’s onboard software to create a millimeter-precision 3D model of the asset, which can be compared with computer-aided-design models or previous-inspection-run data. By using a fully automated 3D-model cross-check, the AUV could detect asset deformations, defects, or marine growth, even while still submerged during the inspection run.

Seafloor AUV Support Infrastructure. Current AUVs have limited endurance, mostly because of limited battery capacity. Depending on the sensor suite, on-board data-storage space also can be a limiting factor. This causes AUV missions to run no longer than a few days at most, depending on AUV size and shape, propulsion, sensor efficiency, and environmental conditions in the deployment area.
Better Safety Performance Measures Can Lead to Change by Improving Conversations
Authors: Wilson Adam
Published: October 2018

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 190663, “Building Better Performance Measures for Better Conversations To Provoke Change,” by A.D. Gower-Jones, W.T. Peuscher, J. Groeneweg, SPE, S. King, and M. Taylor, Tripod Foundation, prepared for the 2018 SPE International Conference on Health, Safety, Security, Environment, and Social Responsibility, Abu Dhabi, 16–18 April. The paper has not been peer reviewed.

For the last 40 years, the oil and gas industry has measured safety performance using injury-frequency rates. Industry thinking is based on the premise that, if we do not have injuries, then we are safe and, if we have injuries, we are not safe. This paper examines the fallacy of that premise and the use of injury rates as a key performance indicator (KPI). It argues that, as a KPI, injury-frequency rate is no longer a valid measure.

The Current Situation

As a KPI, injury-frequency rate has served the industry well. It has driven ownership of safety performance as a line responsibility, allowed senior executives to hold managers accountable for performance, forced leaders to notice injuries, and driven many improvements.

A graph showing performance over a 2-year period would be discussed at management meetings, reasons argued, and actions given to business unit leaders. The data could create a discussion along the lines of “Overall performance is clearly going in the wrong direction. We all need to be concerned.” Pointing to one cause would be difficult, and many theories would be put forward on the basis of this data.

Why Measuring Injury Rates Is Misleading

Research into accident causation has revealed much in the last 30 years. Earlier work resulted in the Swiss Cheese Model (Fig. 1), the Generic Error Modeling System (GEMS) (Fig. 2), and the Tripod Model of Accident Causation (Fig.  3). Two software-based products have been produced from these models; Tripod Beta and Bow Tie analysis both are now mainstream.

Safety leaders no longer think that people are the only cause of accidents (i.e., stupid people doing stupid things). They understand that errors and violations are the product of systemic causes. Accidents happen because barriers fail. Barriers fail because of people’s action or inaction. People are generally trying to do a good job, but they are influenced by their environment. That working environment is created by the way the business is managed.

Accidents are complex events with multiple causes. Controls that fail can be a long distance from, and not related to, individuals who are injured. Normally, more than one control needs to fail before someone is injured. Often, those controls are put in place by different people at different times—an operator isolates equipment, a supervisor checks the isolation, and a technician works on the equipment.
Technology Update: New Instrumented Docking Gun System Maximizes Perforating Performance
Authors: Guedes Carlos Eduardo , Aboelnaga Sharif
Published: October 2018

Technology Update

Accidental detonation of a perforating gun at surface can have catastrophic consequences. To decrease risks, layers of procedural controls have been implemented to reduce the inadvertent application of power caused by human error, stray voltage, or the presence of radio frequency (RF) energy. Explosives handling procedures and controls, such as locking out the firing panel and acquisition system, are used to mitigate the human error risk.

Mitigating RF risks requires establishing RF-free exclusion zones, with all RF transmissions shut down. Exclusion zones are effective, but adhering to them relies on strict procedural controls. With increased industry and personal reliance on RF transmitters, such as cellular phones, RF silence is becoming more difficult to achieve. Although RF-immune initiators were introduced more than 20 years ago to allow wellsite operations to continue without RF silence imposed, their complex initiation technologies require high power levels, which improve the safety margin to stray volt-age but significantly reduce overall system reliability.

Perforating has always been a hands-on operation that relies on supervisor experience. Over the last decade, perforating reliability has continued to improve as service companies and operators have implemented detailed training programs, procedural checklists, and advanced hardware. However, these reliability improvements have begun to plateau, acting as an impetus to develop new perforating systems that would be more effective than procedural controls in addressing the main causes of perforating misruns: damaged or improper wiring, mechanical seal failures, and initiator malfunctions.

Plug-In Design With Built-In Safety

With a focus on resolving these issues, Schlumberger developed the Tempo instrumented docking perforating gun system—the industry’s first perforating system that fully integrates a plug-in gun with real-time advanced downhole measurements for monitoring and confirming operations to mitigate risk while increasing safety, reliability, and efficiency (Fig. 1). Created for all environments, the system uses modularized initiators combined with RF filtering mechanisms and an addressable switch to provide an enhanced level of safety to operations.

Proprietary docking components are the key element of the gun system’s plug-in design. They streamline assembly and eliminate the major cause of perforating misfires: technique-sensitive crimping and wiring. The initiator can be plugged into a perforating gun by using simple mechanical and electrical connections without requiring complicated assembly. The new system eliminates all complex field wiring connections and crimping, which simplifies the arming process that has a direct impact on both wellsite efficiency and reliability.
An Update of the Global Standard in Reserves/Resources Classification and Definitions
Authors: DiLuzio Dan
Published: October 2018

Since its publication in 2007, the SPE Petroleum Resources Management System (PRMS) has been broadly adopted by the petroleum industry as the international standard reference for reserves and resources classification and reporting. The SPE Oil and Gas Reserves Committee (OGRC) continues its commitment to periodically update the PRMS to accommodate changes in technology, commercial arrangements, and, as required, to address evolving industry needs. We are pleased to announce that the 2018 PRMS update has been approved by all sponsoring organizations and by the SPE Board of Directors in June.

How Did We Get There?

An OGRC Update Subcommittee was formed in 2014 to critically review the 2007 document based on industry feedback gathered during a series of workshops over the intervening 7 years. OGRC subgroups examined how the document should be improved and advanced to better support the full range of stakeholders using a standard project-based assessment process while maintaining the key principles. Numerous discussions were held between the sponsoring societies, OGRC members, and other industry experts to develop and refine the draft prior to public comment.

The document was posted for a 90-day public comment period beginning on 15 August 2017. At that time, over 250 personalized letters were distributed announcing the proposed update and requesting feedback from consulting and financial firms, government agencies, and E&P companies. The OGRC Update Subcommittee compiled and assimilated the public responses and made corrections, updates, and clarifications. This draft was submit-ted to the sponsoring societies and the other OGRC members for input and discussion leading to the final version.

The updated document was then approved by SPE and the six co-sponsoring organizations:

World Petroleum Council (WPC)

American Association of Petroleum Geologists (AAPG)

Society of Petroleum Evaluation Engineers (SPEE)

Society of Exploration Geophysicists (SEG)

Society of Petrophysicists and Well Log Analysts (SPWLA)

European Association of Engineers and Geoscientists (EAGE)

The PRMS also provides the commodity-specific specifications for petroleum under the United Nations Framework Classification for Resources (UNFC).

The updated PRMS is now posted at www.spe.org/industry/reserves.

Major Principles Retained

PRMS continues to utilize the same foundation principles contained in the PRMS 2007 document:

The system is “project-based”

Classification is based on a project’s chance of commerciality

Categorization is based on recoverable uncertainty

The base case uses evaluator’s forecast of future conditions

Provides more granularity for project management

Estimates based on deterministic and/or probabilistic methods

Applies to both conventional and unconventional resources

Reserves/resources are estimated in terms of the sales quantities and allowing for fuel consumed in operations (CiO) when reported separately

Net resources are allocated based on contractual entitlement
Lessons From 10 Years of Monitoring With Chemical Inflow Tracers
Authors: Carpenter Chris
Published: October 2018

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 187677, “Ten Years of Reservoir Monitoring With Chemical Inflow Tracers—What Have We Learned and Applied Over the Past Decade?” by A.D. Dyrli and E. Leung, SPE, Resman, prepared for the 2017 SPE Kuwait Oil and Gas Show and Conference, 15–18 October. The paper has not been peer reviewed.

Initial development of inflow tracers was designed to provide qualitative information about the location of water breakthrough in production wells. The proof of concept and application for water detection initiated the development of oil tracers for oil-inflow monitoring. The evolution of inflow-tracer-signal interpretation also has provided valuable insight to inflow characterization. A model-based approach to match the measured signals with proprietary models also has been developed.

Unique Chemical Tracers for Reservoir Surveillance

During the past decade, many unique chemical tracers have been designed. The aim of this development has been to obtain many unique signatures with properties as similar as possible. The strategy involved finding families of chemical molecules that had the potential to provide a large number of unique tracers with a small change in the chemical structure. Today, more than 160 unique signatures exist. More than 80 are within one family of oil markers. 

The chemical tracers and the polymer matrix need to be stable and inert at a wide range of well conditions. No applicable accelerated test methods exist for polymer materials, so long-term functionality must be tested in the laboratory with an environment as realistic as possible to estimate inflow-tracer longevities.

Another important feature of these tracers is the concept of the detection limit. To be able to mark production over decades with a limited amount of material placed in the well, the detection limit must be extremely low. The amount of material is limited because of space, cost, or environmental concern. In 2005, the detection limits were parts per billion, while the detection limit today is below parts per trillion and is expected to move toward parts per quadrillion.

Inflow-Tracer-System Design

Years of laboratory work and field experience have proved that designing systems from experience is crucial. The effect of nontarget fluids and treatment chemicals on different materials is tested over specific time periods according to time of exposure under actual conditions. The qualification tests include treatment chemicals, including solvents and strong acids or bases that may affect the tracer or polymer matrix in which the tracers are embedded. Temperature is one of the major parameters affecting release, and stability and functionality tests for the design will be performed at various temperatures. The use of permanent installed tracers to optimize oil production and reduce water production will reduce the need for water treatment and interventions, thereby reducing the overall environmental impact.
A Higher-Resolution Flow-Oriented Scheme With an Adaptive Correction Strategy for Distorted Meshes Coupled With a Robust MPFA-D Method for the Numerical Simulation of Two-Phase Flow in Heterogeneous and Anisotropic Petroleum Reservoirs
Authors: Souza M. R. , Contreras F. R. , Lyra P. R. , Carvalho D. K.
Published: October 2018

In this paper, we propose a full-cell-centered finite-volume approach to simulate two-phase flow in heterogeneous and anisotropic petroleum reservoirs. We adopt a segregated formulation where the pressure equation is discretized by a multipoint flux approximation with a diamond-type support (MPFA-D). To solve the saturation equation, we propose a higher-order modified flow-oriented scheme (M-FOS). In this scheme, adaptive weights tune the formulation multidimensionality according to the grid distortion. Also, we adopt a multidimensional limiting process (MLP) and an efficient entropy fix to produce convergent solutions. We evaluate the performance of our numerical schemes by solving some relevant benchmark problems.
Analysis of Well-Completion Performance and Production Optimization of a Gas Well Using Computational Fluid Dynamics
Authors: Molina Oscar M. , Tyagi Mayank
Published: October 2018

This paper investigates the effects of high production rates on well performance for a casedhole gas well using two types of completion schemes: frac pack and gravel pack. We model fluid dynamics in the near-wellbore region, where the most dramatic changes in pressure and velocity are expected to occur, using computational fluid dynamics (CFD). The fluid-flow model is dependent on the Navier-Stokes equations augmented with the Forchheimer equation to study inertial and turbulence effects in regions where the velocity increases and decreases sharply over a relatively small length scale. Real-gas properties are incorporated into the momentum-balance equation using the Soave-Redlich-Kwong (SRK) equation of state (EOS) (SRK-EOS). The near-wellbore model is pressure-driven under steady-state and isothermal conditions. Well-performance curves are generated depending on simulation results for both completion schemes. Furthermore, we introduce the concept of rate-dependent pseudoskin factor to assess inertial and turbulence kinetic energy (TKE) losses under various pressure differential. Analysis of the simulation results suggests that the rate-dependent pseudoskin changes from negative at low gas-production rates to positive at medium-to-high gas-production rates. This is primarily because of the inertial and turbulence effects being triggered at a certain flow rate, which we define as the optimal operating point. We demonstrate that the gas-deliverability curve plotted along with the pseudoskin-factor curve allows us to estimate the optimal operating condition as the point where the rate-dependent pseudoskin is zero. An analytical model to estimate the optimal production rate is proposed as an extension to typical multirate tests.
Low-IFT Foaming System for Enhanced Oil Recovery in Highly Heterogeneous/Fractured Oil-Wet Carbonate Reservoirs
Authors: Dong Pengfei , Puerto Maura , Jian Guoqing , Ma Kun , Mateen Khalid , Ren Guangwei , Bourdarot Gilles , Morel Danielle , Bourrel Maurice , Biswal Sibani Lisa , Hirasaki George
Published: October 2018

Oil recovery in heterogeneous carbonate reservoirs is typically inefficient because of the presence of high-permeability fracture networks and unfavorable capillary forces within the oil-wet matrix. Foam, as a mobility-control agent, has been proposed to mitigate the effect of reservoir heterogeneity by diverting injected fluids from the high-permeability fractured zones into the low-permeability unswept rock matrix, hence improving the sweep efficiency. This paper describes the use of a low-interfacial-tension (low-IFT) foaming formulation to improve oil recovery in highly heterogeneous/fractured oil-wet carbonate reservoirs. This formulation provides both mobility control and oil/water IFT reduction to overcome the unfavorable capillary forces preventing invading fluids from entering an oil-filled matrix. Thus, as expected, the combination of mobility control and low-IFT significantly improves oil recovery compared with either foam or surfactant flooding.

A three-component surfactant formulation was tailored using phase-behavior tests with seawater and crude oil from a targeted reservoir. The optimized formulation simultaneously can generate IFT of 10−2 mN/m and strong foam in porous media when oil is present. Foam flooding was investigated in a representative fractured core system, in which a well-defined fracture was created by splitting the core lengthwise and precisely controlling the fracture aperture by applying a specific confining pressure. The foam-flooding experiments reveal that, in an oil-wet fractured Edward Brown dolomite, our low-IFT foaming formulation recovers approximately 72% original oil in place (OOIP), whereas waterflooding recovers only less than 2% OOIP; moreover, the residual oil saturation in the matrix was lowered by more than 20% compared with a foaming formulation lacking a low-IFT property. Coreflood results also indicate that the low-IFT foam diverts primarily the aqueous surfactant solution into the matrix because of (1) mobility reduction caused by foam in the fracture, (2) significantly lower capillary entry pressure for surfactant solution compared with gas, and (3) increasing the water relative permeability in the matrix by decreasing the residual oil. The selective diversion effect of this low-IFT foaming system effectively recovers the trapped oil, which cannot be recovered with single surfactant or high-IFT foaming formulations applied to highly heterogeneous or fractured reservoirs.
Evaluation of Software-Based Early Leak-Warning System in Gulf of Mexico Subsea Flowlines
Authors: Thiberville C. J. , Wang Y.. , Waltrich P.. , Williams W. C. , Kam S. I.
Published: October 2018

Early detection of subsea pipeline leaks is a very serious and ongoing issue for the oil and gas industry with limited successful cases reported. For example, aerial surveillance of pipelines can be applied only for relatively shallow and concentrated areas, and an advanced technology such as fiber-optic cable can be considered at the significant expense of time and cost for installation and equipment. The objective of this study is to evaluate a software-based leak-detection technique through complex multiphase flow mechanics. More specifically, this study investigates (i) how leak-detection problems can be formulated from a fluid-mechanics viewpoint and (ii) how reliable such a technique can be under conditions resembling the deepwater Gulf of Mexico (GOM). In examining a wide range of scenarios, this study proves that software-based techniques have a potential for playing a key role in the future.

First, this study defines a base case selected from the literature review of deepwater GOM flowlines in terms of pressure and temperature conditions, fluid properties, reservoir properties, and flowline characteristics that allows a steady-state flow in pipeline to be determined with no leak present. Next, leaks with certain opening sizes (dleak) at different longitudinal locations (xD = x/L) are positioned, and new steady states in the presence of leaks are calculated. By comparing the two steady-state responses (with and without leak), finally, the changes in two leak-detection indicators [i.e., change in upstream pressure (ΔPin) and change in downstream total flow rate (Δqt out)] can be calculated in a wide range of input parameters. This study presents the results in the form of contour plots for pressure and flow responses.

The major finding of this study is that, theoretically, it is possible to estimate both size and longitudinal location of the leak with the two leak-detection indicators in the software-based leak-detection method. The results from various subsea flowline conditions [such as different gas/oil ratios (GORs) and fluid types, water depths, pressures at the receiving facilities, inclination angles, pipe diameters, water cuts, and so on] show that the reliability of this technique is improved when the sink term (i.e., amount of leaking fluid) is more dominant, which, in turn, means that leaks positioned farther upstream, with larger opening size, and occurring at higher pressure inside pipe are relatively easier to detect. In many of the scenarios considered, Δqt out as a leak-detection indicator shows more than a 10% change in the presence of a leak with dleak>1 in., allowing relatively easier activation of a leak-warning system, which demonstrates the robustness of this technique. Other scenarios in which the indicators are less than a few percent changes, however, may be challenging—in those cases, additional responses from other methods (hardware-based or transient simulation) will be helpful.
Improved Method of Moment To Determine Mobile-Phase Saturations Using a Single-Well Chemical-Tracer Test
Authors: Tian Wei , Wu Xingru , Shen Tong
Published: October 2018

The single-well chemical-tracer test (SWCTT) has been applied for decades with much success in estimating residual oil saturation in near-wellbore locations. The information obtained from an SWCTT is critical for designing a method for enhanced oil recovery (EOR). However, a key assumption in the conventional SWCTT is that only single-phase (water) is mobile. In reality, this is often not the case, and significant error can occur if the conventional SWCTT analysis method is used when multiple phases flow at the same time. The objective of this study is to improve the accuracy and precision of SWCTT interpretation in a multiphase-flow condition.

In this paper, we propose an innovative procedure of SWCTT and modify the method of moment (MOM), aiming at the two-mobile-phase condition. In the development of the algorithm, a ratio parameter is introduced to adjust the calculated swept-volume difference between the conservative tracer and the partitioning tracer. In addition, a mixture injection of oil and water is required, instead of the pure-water injection in an SWCTT.

The proposed approach is verified through numerical simulation on synthetic cases with known input parameters. The model being simulated consists of a radial-flow regime with a single vertical well in the center. The input oil saturation varies from 0.1 (immobile oil saturation) to 0.9. Our results show that the saturation estimated from the modified MOM matched the simulation input data, indicating that our approach is able to capture the saturations under two-mobile-phase condition. Moreover, the modified MOM can also be applied in single-mobile-phase condition and can improve the accuracy of conventional MOM.
Downhole-Gauge-Data Analysis of Openhole Gravel-Packing Treatments: Method and Examples
Authors: Kumar A.. , Beldongar M.. , Agee D.. , Gadiyar B. R. , Parlar M..
Published: October 2018

Two key benefits of downhole-gauge (DHG)-data analysis are identifying and minimizing the root causes of any failures that might occur during gravel packing and calibrating or verifying friction-pressure data for gravel-placement simulations. Although downhole pressure and temperature gauges are used often in openhole gravel packing, and expertise in analyzing the data certainly exists in companies that routinely use DHGs, to our knowledge, there is no publication that comprehensively discusses the method of analysis. DHG-data analysis, in general, requires more information than the gauge data themselves. This includes logs, wellbore schematic, pumping schedule, fluid properties, return-flow measurements, daily rig reports, and data relevant to displacements.

The objective of this paper is to provide guidelines for DHG-data analysis to completion engineers, who are not routinely involved and thus are not experts in such analysis, by detailing the factors that must be kept in mind, offering a method, and demonstrating this method with several examples.
Estimating Unpropped-Fracture Conductivity and Fracture Compliance From Diagnostic Fracture-Injection Tests
Authors: Wang HanYi , Sharma Mukul M.
Published: October 2018

A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures.

During the past 2 decades, the DFIT has evolved into a commonly used and reliable technique to obtain in-situ stresses, fluid-leakoff parameters, and formation permeability. The pressure-decline response across the entire duration of a DFIT reflects the process of fracture closure and reservoir-flow capacity. As such, it is possible to use these data to quantify changes in fracture conductivity as a function of stress. In this paper, we present a single, coherent mathematical framework to accomplish this. We show how each factor affects the pressure-decline response, and the effects of previously overlooked coupled mechanisms are examined and discussed. Synthetic and field-case studies are presented to illustrate the method. Most importantly, a new specialized plot (normalized system-stiffness plot) is proposed, which not only provides clear evidence of the existence of a residual fracture width as a fracture is closing during a DFIT, but also allows us to estimate fracture-compliance (or stiffness) evolution, and infer unpropped fracture conductivity using only DFIT pressure and time data alone. It is recommended that the normalized system-stiffness plot (NS plot) be used as a standard practice to complement the G-function or square-root-of-time plot and log-log plot because it provides very valuable information on fracture-closure behavior and the properties of fracture-surface roughness at a field-scale, information that cannot be obtained by any other means.