bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comments: Short-Term Pessimism for Gas
Authors: Donnelly John 
Published: February 2015

Editor's column
Chevron's decision last month to put its North American land-based natural gas drilling on hold highlights not only how tough things have become for drillers but also this year's divergence in oil and gas prices. Chevron cited poor demand and said it does not make sense to continue drilling and producing gas at depressed prices. Other operators and service companies also were pessimistic about the outlook for gas drilling for the rest of this year when announcing second quarter earnings.
Gas prices in the US are at about a fourth of their value compared with a year ago. Oil prices have rebounded to half of their highs from last year, but the gas market finds itself hampered by new competing supplies from unconventionals, pipeline constraints, and built-in barriers to trade that oil does not face.
In addition to poor demand caused by the recession, drillers are a victim of their own success. The growth of new unconventional gas-shale resources has created a significant oversupply that has helped beat down gas prices. Shale development has become prolific—at Barnett in Texas, Haynesville in Louisiana, and Marcellus in Pennsylvania, among others. Unconventional gas supplies seem to be gradually displacing conventional gas production in the US, a pattern that could be repeated in many parts of the world. Recently, energy companies in Europe have begun to turn more to unconventionals in light of maturing gas fields and concerns of dependence on Russian gas supplies.
Finding and development costs for unconventional production have fallen, and technology advancements have greatly improved unconventional development prospects. Unconventional gas production has been growing sharply since 1990, even as conventional offshore and onshore gas output has declined. In addition, last year's high gas prices led to stepped up drilling, efforts paying off this year in increased production.
Gas is not as tradable or as "moveable" as oil, which is part of the reason efforts to form a global gas cartel, similar to OPEC, have not gotten far. In the US, there is often a disconnect among new gas supplies, gas demand centers, and pipeline infrastructure or capacity. That makes gas prices regionalized, unlike oil, which limits trade that would naturally follow supply and demand signals.
The increasing efficiency in gas-shale development and the exciting new prospects have encouraged some operators to continue drilling this year, including Chesapeake Energy and Anadarko. Early results from the Marcellus-shale development—it is estimated to contain 3 billion to 6 billion cubic feet of recoverable gas—have led Anadarko to believe that it could be a star in its onshore portfolio.
The short-term outlook for gas prices is not good, despite what oil prices do. Gas-shale producers are likely to keep drilling. And new liquefied natural gas imports, not to mention new promising Canadian production such as Horn River, should only add pressure on gas.
Uncertainty and the Volumetric Equation
Authors: Murtha Jim , Ross Jim 
Published: February 2015

Guest editorial
Every few years, the topic of correct inputs for use in the volumetric equation re-emerges. Our first recollection is from the 1997 SPE Hydrocarbon Evaluation and Economics Symposium when a dozen or so attendees remained after a session to discuss a logical flaw in a technical paper. All of those present agreed that they had been doing volumetric estimates incorrectly, due to their choice of distributions, and vowed to correct the situation. More recently, in the spring and summer of 2007, SPE's Reserves and Economics Technical Interest Group had a lively discussion on the same topic that ended without resolution and with extensive misunderstanding, in part because of perceived repetition of arguments. Now with the recent release of new reserves definitions and disclosure rules from the US Securities and Exchange Commission and comparisons with the Petroleum Resources Management System developed by SPE and other organizations, we may see more companies using probabilistic methods to estimate hydrocarbons in place, resources, and reserves, so we believe that it would be useful to reiterate the conclusion of those present at that 1997 meeting in Dallas.
The crux of the issue is: What is the correct mathematical basis for establishing appropriate uncertainty distributions as inputs to a probabilistic analysis of the volumetric equation? More specifically: Should the input distribution for each reservoir parameter be based on eitherThe range of values seen in the well data for that parameter, or,The range of uncertainty in the reservoir average for that parameter?

A Simple Model
For illustrative purposes, consider using the volumetric equation in the form: oil initially in place (OIIP)=7758Ahφ(1−Sw)/Bo. The following discussion would also apply to other forms of the equation, such as using gross rock volume and net-to-gross ratio, for example.
The total area of the reservoir, A, is 1,920 acres and 24 wells have been drilled on the basis of 80 acre spacing. The net pay, h, varies between 11 and 165 ft in the wells drilled to-date (Table 1) and statistical analysis of the net pay in the 24 wells shows that the average (mean) net pay is 81.5 ft. For the full calculation of OIIP, we would also need to consider uncertainties in area, porosity, water saturation, and the oil formation volume factor, but we will focus on net pay here.
Perforating System Enhances Testing and Treatment of Fracture-Stimulated Wells
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 116226, "Next-Generation Perforating System Enhances the Testing and Treatment of Fracture-Stimulated Wells in Canada," by M.R.G. Bell, SPE, GEODynamics, and D.A. Cuthill, SPE, Weatherford, prepared for the 2008 SPE Annual Technical Conference and Exhibition, Denver, 21–24 September. The paper has not been peer reviewed.
Ineffective perforations adversely affect the completion of fracture-stimulated wells. If the interval is to be tested before fracturing, a clean connection to the formation is required to obtain meaningful data. Low perforating efficiency and variations in perforation cleanup associated with heterogeneous formations can result in uneven treatment distribution and suboptimal completion. A new charge technology has been deployed in Canada. Specific examples show how the system facilitates prefrac evaluation, fracture initiation, and limited-entry fracture stimulation.

Introduction
Shaped-charge perforators are used to create a flow path between formations of interest and the wellbore in cased and perforated completions. Alternative methods include mechanical penetrators or hydroabrasive-jetting tools. Although quick and simple to deploy, shaped charges still provide an imperfect solution.
As Fig. 1 shows, shaped charges are formed by compressing high-explosive powder within a metal case by use of a conical or parabolic metal liner. When the explosive is detonated, the symmetry of the charge causes the metal liner to collapse along its axis into a narrow focused jet of fast-moving metal particles. When the charge is positioned perpendicular to the wellbore casing, the jet penetrates the casing and the surrounding cement sheath and formation rock. In this displacement mechanism, where the steel, cement, and rock are pushed aside by the jet, the process continues until the speed of the jet falls below some critical velocity and cannot penetrate further. The effectiveness of this perforation tunnel is determined by its geometry and quality.

Tunnel Geometry and Quality.
The distance the tunnel extends into the formation, commonly referred to as the total penetration, is a function of the explosive weight of the shaped charge; the size, weight, and grade of the casing; the prevailing formation strength; and the effective stress acting on the formation at the time of perforating. Effective penetration is the fraction of the total penetration that contributes to inflow or outflow of fluid, and it depends on the amount of compacted debris left in the tunnel after the perforating event. Effective penetration may vary significantly from one perforation to another, and, currently, there is no means of measuring effective penetration in the borehole. The effective penetration determines the effective wellbore radius, an important term in the Darcy radial-inflow equation.
Revitalizing Old-Asset Oil Fields Into Intelligent Fields
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 126067, "Revitalization of Old Asset Oil Fields into I-Fields," by Mohammed N. AI-Khamis, SPE, Konstantin I. Zorbalas, SPE, Hassan M. AI-Matouq, and Saleh M. Almahamed, Saudi Aramco, prepared for the 2009 SPE Saudi Arabia Section Technical Symposium and Exhibition, Al-Khobar, Saudi Arabia, 9–11 May. The paper has not been peer reviewed.
Recent advances in oilfield technologies have led to the emerging development of intelligent fields. Integrating these technologies whether downhole or at the surface, coupled with communication networks and sophisticated simulation and monitoring applications, provided significant advancements in monitoring and control capabilities and in decision-making processes. An overall system upgrade in Saudi Arabia resulted in enhanced field surveillance, which led to higher levels of oil production.

Introduction
The Abu Hadriya, Fadhili, and Khursaniyah (AFK) complex consists of three fields that share a common surface infrastructure for fluid-processing facilities and pipelines. Production from the AFK fields started in the early 1960s, but the fields were shut-in from 1983 to 1990 because of the low demand for oil in the international markets. The early production from all of the producing reservoirs was supported by gravity injection because the facilities did not have power water-injection capability and all produced associated gas was flared because there was no gas-handling facility.
Saudi Aramco has embarked on the development of several fields, including the AFK fields, with an aim to transform the mature and remote fields into state-of-the-art intelligent fields equipped with proper handling facilities for oil, water, and gas. The new AFK project is a twofold plan. The first part called for drilling new wells, both oil producers and water injectors. The newly drilled water-injection wells are part of a planned peripheral water-injection program for pressure maintenance. The second part implements intelligent-field components that will enhance automation as well as the communication net-work between downhole equipment and surface facilities. Construction included a new processing facility to handle 500,000 BOPD of Arabian Light crude blend, a new gas plant to process 1 Bcf/D of sour gas from this and other nearby fields, a water-injection plant with a capacity of 1.1 million BWPD to support reservoir pressure, and a complete infrastructure of flowline networks to interconnect the three fields with the centralized processing facility.
En Route: The Endless Battle for a Positive Industry Image
Authors: Labastie Alain 
Published: February 2015

President's column
The oil and gas industry has long had a poor image among the general public, especially in western countries. Today, two events have captured the minds of many people, and we must recognize that they reinforce that poor image: last year’s Macondo disaster in the Gulf of Mexico, and the current controversy about environmental damage (drinking-water contamination) related to shale gas development. What should we do about these perceptions?
First, we have to make ourselves heard and explain the important achievements our industry has made and the significant benefits our industry has provided to mankind:
The oil and gas we are producing is more than fuel for our cars or our aircraft; they are really the fuel for the world economy. The incredible life-style improvement in most countries over the last century was made possible mostly by an abundant supply of energy, especially hydrocarbons.
Our industry creates jobs through the entire world. Today, the development of shale gas is creating jobs in North America; we could see new jobs in Europe in some near future if this activity develops. And these days, jobs are more than welcome in many countries, in the aftermath of financial crisis and surge of unemployment.
Developing domestic resources will help many countries to decrease their trade deficit, which is a significant contribution in this period of debt crisis.
In the past 10 years, mostly through the International Association of Oil & Gas Producers, the industry has developed a reliable and, most importantly, credible system for reporting its environmental performance. And the trends are good for both CO2 emissions (stable even if oil and gas production has increased) and hydrocarbon discharges (decreasing with obviously the exception of 2010 due to Macondo).
Hydraulic Fracturing Technology and Reporting Continue to Evolve
Authors: Schorn Patrick 
Published: February 2015

Management
Used commercially since the 1940s, hydraulic fracturing technology has consistently fulfilled its purpose of extending conductive pathways deep into the reservoir and maximizing production of hydrocarbons. Over the years, significant improvements in fracturing technology and technique have been made, and its application has become common. Since the advent of unconventional reservoir development, fracturing operations have increased several times over in terms of numbers of wells fractured, horsepower requirements, and volumes pumped. Today, for projects aimed at commercial exploitation of many unconventional resources, hydraulic fracturing has moved from a desirable option to necessity and, in many cases, the only way to economically produce these plays.
Nevertheless, lately the practice has been called into question. Fracturing has been blamed as the cause for a variety of events that concern the general public—from earthquakes to groundwater pollution—and the service industry has not done enough to address these fears. In part, the flames of public fears have been fanned by a lack of transparency surrounding the composition of frac fluids. Service companies have been reluctant to make this information public because they believe it is part of their competitive edge. Service companies and chemical suppliers spend significant amounts of capital and effort developing high-performance stimulation chemistry and they naturally seek a certain measure of protection for the resulting intellectual property. However, there are ways in which disclosure and transparency can be achieved while addressing industry concerns about intellectual property.
It should be noted that hydraulic fracturing continues to be the safest and most economical method available for developing unconventional hydrocarbons. And even in the midst of current controversy, the process and the technology must continue to improve and the industry benefit from further optimization.
Operators and service companies alike are striving to develop more effective hydraulic fracturing solutions. Their goal is to achieve economic production while using less water, proppant volumes, and horsepower and with fewer trucks in order to reduce emissions. The industry is also highly focused on developing fracturing chemistry with an improved environmental profile. The more successful the initiatives, the more sustainable and internationally transferable these unconventional development practices will become.
Some of the immediate topics being addressed by industry include improvements in well integrity assurance with respect to hydraulic fracturing, water volume requirements, flowback capture and treatment, and reporting and disclosure of the ingredients of the fluid mixtures pumped downhole.
Technology Focus: Completions Today (September 2011)
Authors: Horvat Damir 
Published: February 2015

Technology Focus
Reviewing the numerous papers for this feature showed that the primary theme throughout the last 12 months, globally, has been intelligent-completion methodologies. Fine tuning this information, it is further seen that the primary interest was reservoir surveillance, reservoir deliverability, and production optimization.
In line with the latest generation of objectives, the scope of real-time optimization may be focused on three major segments: well-performance-model update, well-performance monitoring, and reservoir monitoring. Latest-generation real-time-optimization systems can calculate a voidage-replacement ratio for a given completion/reservoir and its subsections on the basis of daily surface-allocated production and injection. The system alerts the user about any parameter that is outside defined bounds of a voidage-replacement ratio, providing optimization engineers with an indication of given areas of the completion/reservoir that are under- or overinjected.
Also, in recent years, the upstream petroleum industry has been honing its ability to drill and complete increasingly-longer higher-angle wells along complex well paths. In addition, live-well-deployment systems deploy and retrieve perforating guns without needing to kill the well. Whether using wireline, coiled tubing, or snubbing pipe, these advanced deployment systems perforate multiple, or longer, intervals in one run to reduce rig time and completion cost.
Application of intelligent-well-completion technology has continued to grow within the industry, even in the face of perceived risks associated with installation and longevity of the system. Operating companies may face challenges (e.g., the subsurface may be characterized by a double-plunging anticline structure with a thrust fault along the main axis and multiple flank normal faults dividing the three major reservoirs into five or six main producing areas). Furthermore, each major reservoir may be subdivided vertically into more subreservoirs. Pressure maintenance may be by use of peripheral water injection or produced-gas reinjection.
I am, therefore, pleased that many operating and service companies have started a significant research partnership. The research is aimed at finding and developing new completion methodologies and technologies for enhanced production, with the aim of addressing many of the challenges in the upstream petroleum industry.
Completions Today additional reading available at OnePetro: www.onepetro.org
SPE 141456 • “Best Practices for Multizone Stimulation Using Composite Bridge Plugs” by Douglas J. Lehr, SPE, Baker Hughes, et al.
SPE 138322 • “Frac Sleeves: Is Milling Them Out Worth the Trouble?” by G. Wozniak, EQT Resources
SPE 130219 • “Nonuniform Slotted-Liner Completion, a New Approach To Obtain Uniform Production Profile Along Horizontal Wells” by M. Mohammadsalehi, Iranian Central Oilfields Company, et al.
Offset Bow Centralizers Meet Underreamed Well Challenges
Authors: Boncutiu Marius , Berry Richard 
Published: February 2015

Technology Update
Underreamed wells are among the toughest challenges to using a centralizer, a device that keeps the casing or liner in the center of a wellbore. Underreaming, the technique of enlarging of a wellbore beyond its originally drilled size, is a drilling method widely used to increase the openhole size, which may be required for various reasons.
Some well planners believe it is safest to drill unknown shallow formations with a small diameter bit and enlarge the pilot hole if no gas is encountered. Underreaming may also be performed if a small additional amount of annular space is desired, for example, if a liner must be run to protect against surge pressures.
A fundamental problem with under-reamed wells is achieving effective casing centralization in the underreamed section. The job of the centralizer is to center the casing to improve run in hole (RIH), allow easier pipe rotation, and to enable the cement column to circulate freely around the tubular and produce a robust cement seal to ensure zonal isolation.
Mud displacement is vital to achieving a good cement bond. The more central the pipe, the more efficient the mud displacement will be. In deviated and horizontal wells, if the tubular is not centralized, it will lie along the low side of the borehole and make cement circulation and the achievement of a uniform cement sheath difficult.
Poor centralization can also impair the cement bond by causing channeling, which can lead to various live annulus problems. Like any fluid, cement will take the easiest route in the annulus, and this can result in an inadequate seal if the casing or liner is not centralized. In addition, if the annular clearance is restricted in some sections, backpressure may result that requires a much reduced flow rate during cementation to avoid fracturing the formation and thereby losing fluid.
Offset Bow Centralizer
The Uros offset bow centralizer developed by Centek is designed for use in underreamed or washed-out well sections. The device significantly reduces initial insertion forces and drag when running through previously set casing. Once through this compressed stage, the offset bow centralizer will revert to its designed outer diameter in the open hole and thus maximize standoff without additional drag. The device achieves a reduction in drag compared with other centralizers because of its patented bow design, in which the high points of the bows are offset alternately without reducing the strength of the unit or its capacity to centralize the casing in the open hole.
Intelligent Inflow Tracers Obtain Information With Less Risk, Cost
Authors: Williams Brock , Carvalho Vinicius 
Published: February 2015

Young Technology Showcase
Today’s field developments are increasingly characterized by complex wells in demanding and costly operating environments. Not only are individual wells challenging, but most are part of a complex reservoir network that must be managed over an extended period.
The high cost and risk of acquiring reservoir surveillance information using conventional technology, such as production logging tools, is forcing operators to manage these fields without knowledge of the inflow distribution across the reservoir interval. In addition, permanent reservoir surveillance solutions based on optical or electronic sensors require major modifications of the completion design and installation procedure. Consequently, a significant amount of complexity and risk are added to the project, making the use of such technologies prohibitive.
Intelligent chemically based inflow tracer systems are an emerging technology that consist of engineered polymers and chemical compounds combined into a product that resembles strips of plastic. The tracer system is designed to react to either oil or water. For example, when a water-sensitive tracer system is contacted by water, the tracer system releases its unique chemical identification (inflow tracer) at a prescribed release rate, irrespective of the flowing conditions. The water-sensitive tracer system is dormant when contacted by oil, gas, or air. The oil-sensitive tracer system behaves similarly as the tracer is released only when it comes in contact with oil.
Strips of the tracer system are readily integrated into almost any completion configuration including conventional sand screens, inflow control device (ICD) sand screens, multistage fracturing systems, pup joints, and intelligent completions. Additionally, the tracer system can be cemented behind casing and perforated through, providing contact between reservoir fluids and the intelligent tracer strips. In summary, the intelligent tracer strips can be deployed in almost any well type without affecting the installation process.
Samples of produced fluid are analyzed for the concentration of each intelligent tracer. Tracer concentration data, combined with model-based interpretation techniques, enables the operator to understand where oil is entering the well, where water influx is occurring, and relative oil contributions of monitored zones.