bluuebunny/crossref_metadata_2025 huggingface dataset:
Proppant Placement Using Alternate-Slug Fracturing
Authors: Malhotra Sahil , Lehman Eric R. , Sharma Mukul M.
Published: June 2014

New fracturing techniques, such as hybrid fracturing (Sharma et al. 2004), reverse-hybrid fracturing (Liu et al. 2007), and channel (HiWAY) fracturing (Gillard et al. 2010), have been deployed over the past few years to effectively place proppant in fractures. The goal of these methods is to increase the conductivity in the proppant pack, providing highly conductive paths for hydrocarbons to flow from the reservoir to the wellbore. This paper presents an experimental study on proppant placement by use of a new method of fracturing, referred to as alternate-slug fracturing. The method involves an alternate injection of low-viscosity and high-viscosity fluids, with proppant carried by the low-viscosity fluid. Alternate-slug fracturing ensures a deeper placement of proppant through two primary mechanisms: (i) proppant transport in viscous fingers, formed by the low-viscosity fluid, and (ii) an increase in drag force in the polymer slug, leading to better entrainment and displacement of any proppant banks that may have formed. Both these effects lead to longer propped-fracture length and better vertical placement of proppant in the fracture. In addition, the method offers lower polymer costs, lower pumping horsepower, smaller fracture widths, better control of fluid leakoff, less risk of tip screenouts, and less gel damage compared with conventional gel fracture treatments.

Experiments are conducted in simulated fractures (slot cells) with fluids of different viscosity, with proppant being carried by the low-viscosity fluid. It is shown that viscous fingers of low-viscosity fluid and viscous sweeps by the high-viscosity fluid lead to a deeper placement of proppant. Experiments are also conducted to demonstrate slickwater fracturing, hybrid fracturing, and reverse-hybrid fracturing. Comparison shows that alternate-slug fracturing leads to the deepest and most-uniform placement of proppant inside the fracture. Experiments are also conducted to study the mixing of fluids over a wide range of viscosity ratios. Data are presented to show that the finger velocities and mixing-zone velocities increase with viscosity ratio up to viscosity ratios of approximately 350. However, at higher viscosity ratios, the velocities plateau, signifying no further effect of viscosity contrast on the growth of fingers and mixing zone. The data are an integral part of design calculations for alternate-slug-fracturing treatments.
Some Phenomena Pertinent to Velocity Logging
Authors: Wyllie M.R.J. , Gardner G.H.F. , Gregory A.R.
Published: June 2014

The main experimental facts relating to an understanding and interpretation of the Continuous Velocity Log are reviewed. Experience shows that the velocity through liquid-saturated rocks primarily depends on porosity, and that the "time-average" formula can be relied on to give the dependence within about 5 per cent. An exception occurs in the case of shallow unconsolidated sands. Data are given for the dilatational and shear velocities through dry rocks under a high confining stress. It is argued that a correction made for pressure increase or porosity reduction with depth in the interpretation of a velocity log is unwarranted because of the many uncertain parameters involved.

The application of Biot's theory is discussed, and illustrated with a numerical example. If tile dilatational and shear velocity in the dry material are known, then the change in velocity on saturating the material with any inert fluid is explicitly expressed in terms of the density and compressibility of the fluid. However, since the dry velocities of rocks in the ground are not known, and their correlation with porosity is small, the practical use of Biot's theory is very limited. As a didactic tool it achieves its greatest usefulness.

Introduction

The introduction of the Continuous Velocity Log (CVL) as a routine logging device is a significant technical feat, but even more remarkable has been its wide acceptance as a tool to solve problems in correlation and to determine the porosities of subsurface beds. Indeed in the latter regard it has been recently described as the best wireline tool now available for the evaluation of porosity. While this statement seems to ignore definite drawbacks in the use of CVL data to calculate porosities, world-wide experience in the interpretation of CVL data by the so-called "time-average" technique has shown it to be extraordinarily successful.

The primary intention in this paper is to review the major experimental facts which must be considered when interpreting CVL data. A secondary purpose is to show how some of these data can be explained by modification of the classic theory of wave motion in continuous matter. The third aim, but by no means the least important one, is to remark on some of the misconceptions which appear to have crept into current interpretation procedures and to emphasize where experimental and theoretical lacunae exist.
Engineering Cementing Solution for Hutubi Underground-Gas-Storage Project
Authors: Zhang X.. , Taoutaou S.. , Guo Y.. , An Y.. , Zhong S.. , Wang Y..
Published: June 2014

Underground gas storage (UGS) is an important segment in China's gas market. Because of the supply-and-demand misbalance of natural gas, the gas in underground storage is made available during the peak winter season. In the west of China, the Hutubi dry-gas field is to be used for UGS with a storage capacity of 4.5 × 109 m3. A total of 37 wells will be drilled with 30 natural-gas-injection/-withdrawal wells, five observation wells, and two water-injection wells. UGS relies on proper wellbore construction and the sealing function of the caprock. The selection of the type of cement is crucial to having a healthy well that will last to meet the gas-storage need of 30 years under high-intensity injection. The gas injection and withdrawal will induce different stresses on the cement sheath and may destroy the seal by either debonding (microannulus) or cracking; an effective cement system is required to prevent the leakage of the gas and flow through the caprock. A specialized cement technology was identified as a solution to UGS and was deployed successfully in the Hutubi field with good results. The cement selected had to meet the pressure and temperature challenges associated with UGS, and a methodology was established to qualify the new sealant. Case histories of three wells illustrate the steps taken in cementing UGS wells in the field.
Novel High-Efficiency Boron Crosslinkers for Low-Polymer-Loading Fracturing Fluids
Authors: Legemah Magnus , Guerin Michael , Sun Hong , Qu Qi
Published: June 2014

Boron-based crosslinkers are used commonly to increase viscosity and to improve fluid-loss control and proppant transportability of guar and its derivative fluids. Boron crosslinkers are usually preferred because of their ability to reheal after shearing and their favorable environmental properties. More-efficient crosslinkers capable of crosslinking fluids with reduced polymer loading have always been of great interest, to reduce both the formation and the proppant-pack damage from polymer residues and to reduce overall fluid cost, especially with the reduced availability and higher cost of guar.

Recently, we reported in paper SPE 140817 (Sun and Qu 2011( the synthesis of polyaminoboronates, bulky compounds containing multiple boron sites and capable of interacting with multiple polysaccharide strands to form more complex crosslinking networks at lower polymer loadings than conventional guar fluids. However, to improve the marketability and acceptance of the product, a lower-cost combination of raw materials is sought. In addition, a delaying mechanism to improve the control of the fluid-viscosity buildup can make the product fit into broader applications.

A readily available polyamine was used as the base scaffold, and boron was incorporated by means of intermediate borate formed in the condensation reaction between boric acid and ethylene glycol to replace volatile and highly flammable trimethylborate. New chemistry was developed to produce more-controlled crosslinking. The resulting compound exhibited desired adjustable delay characteristics.

This paper shows the effect of a series of new crosslinkers in terms of delay properties. The testing results of fluids with a 20%-lower polymer loading, crosslinked with the new crosslinker, are reported and compared with those of conventional fluids. Analysis and discussion of the chemistry, crosslinker performance, and economics are presented.
Formation Evaluation with the Wireline Tester - Merits and Shortcomings
Authors: Milburn J.D. , Howell J.C.
Published: June 2014

The wireline formation tester has proved to be a valuable tool for formation evaluation, but some tests still lead to misleading interpretations while others are inconclusive. Longer flow periods and more tests are generally required for evaluation of low-permeability sands. No particular advantages or disadvantages were found for tools with large, small and/or segregated chambers.

The methods of interpretation presently in use have proved to be quite accurate; however, care must be exercised to determine that the conditions required for use of these methods are satisfied and that the tool functions properly. Errors in the measurement or recording of recoveries have probably resulted in many misleading interpretations; simply stating all volumes in the same units would speed interpretation and be helpful in recognizing errors.

A single chart for interpretation of formation test recoveries from all sizes of chambers is presented. The surface pressure is helpful in the detection of a leaky seal, but it should not be used to correct for losses caused by leaks. Water resistivity data may be misleading when used to predict whether a zone would produce water and hydrocarbons or water alone.

The wireline formation tester is a dependable tool for obtaining pressure measurements; however, the estimation of formation permeability from pressure build-up has been found to be qualitative at best.

Introduction

The wireline formation tester was introduced to the industry in 1955 by the Schlumberger Well Surveying Corp. It proved so successful that thousands of tests have been run to date and most logging companies now offer this service. It is a valuable addition to the array of wireline tools currently being used for formation evaluation and is the only one, other than the side-wall sampler, that obtains physical evidence of formation contents.
Uncertainty-Based Approach for Predicting the Operating Window in UBO Well Design
Authors: Udegbunam J.E.. E. , Fjelde K.K.. K. , Arild Ø.. , Ford E.. , Lohne H.P.. P.
Published: June 2014

Underbalanced operations (UBO) are carried out to bypass drilling challenges that could be difficult to resolve by use of conventional drilling techniques. Steady-state multiphase-flow models are used to construct underbalanced-drilling operational windows. These advanced software models are deterministically formulated. It is known that some of the model input parameters, such as the multiphase-flow parameters, friction factors, and reservoir productivity, are subject to uncertainties. Failures to capture these variabilities may introduce some error in the model prediction, resulting in poor well planning and implementation.

The purpose of this work is to implement probabilistic modeling of underbalanced drilling by use of a simple steady-state two-phase model. Both predefined uncertain and fixed factors serve as inputs to a pre-existing deterministic model. By applying Monte Carlo simulations, the model predicts outputs that follow a statistical distribution. A sensitivity analysis is conducted to determine the input factor that is most responsible for the uncertainty in the predicted bottomhole pressure (BHP).

The results demonstrate that uncertainty modeling can improve underbalanced-drilling design and operations. A more realistic operational window is obtained, ensuring that underbalanced condition is maintained throughout the target section.

With a better understanding of uncertainties and the corresponding impacts, well planners can make better decisions regarding well design criteria and safe operational conditions, and avoid huge economic consequences.
Experimental and Modeling Study of Salt Precipitation During Injection of CO2 Contaminated With H2S Into Depleted Gas Fields in the Northeast of the Netherlands
Authors: Bolourinejad P.. , Herber R..
Published: June 2014

Depleted gas fields are among the most probable candidates for subsurface storage of carbon dioxide (CO2). With proven reservoir and qualified seal, these fields have retained gas over geological time scales. However, unlike methane, injection of CO2 changes the pH of the brine because of the formation of carbonic acid. Subsequent dissolution/precipitation of minerals changes the porosity/permeability of reservoir and caprock. Thus, for adequate, safe, and effective CO2 storage, the subsurface system needs to be fully understood. An important aspect for subsurface storage of CO2 is purity of this gas, which influences risk and cost of the process. To investigate the effects of CO2 plus impurities in a real case example, we have carried out medium-term (30-day) laboratory experiments (300 bar, 100°C) on reservoir and caprock core samples from gas fields in the northeast of the Netherlands. In addition, we attempted to determine the maximum allowable concentration of one of the possible impurities in the CO2 stream [hydrogen sulfide (H2S)] in these fields.

The injected gases—CO2, CO2+100 ppm H2S, and CO2+5,000 ppm H2S—were reacting with core samples and brine (81 g/L Na+, 173 g/L Cl−, 22 g/L Ca2+, 23 g/L Mg2+, 1.5 g/L K+, and 0.2 g/L SO42−). Before and after the experiments, the core samples were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) for mineralogical variations. The permeability of the samples was also measured. After the experiments, dissolution of feldspars, carbonates, and kaolinite was observed as expected. In addition, we observed fresh precipitation of kaolinite. However, two significant results were obtained when adding H2S to the CO2 stream. First, we observed precipitation of sulfate minerals (anhydrite and pyrite). This differs from results after pure CO2 injection, where dissolution of anhydrite was dominant in the samples. Second, severe salt precipitation took place in the presence of H2S. This is mainly caused by the nucleation of anhydrite and pyrite, which enabled halite precipitation, and to a lesser degree by the higher solubility of H2S in water and higher water content of the gas phase in the presence of H2S. This was confirmed by the use of CMG-GEM (CMG 2011) modeling software.

The precipitation of halite, anhydrite, and pyrite affects the permeability of the samples in different ways. After pure CO2 and CO2+100 ppm H2S injection, permeability of the reservoir samples increased by 10–30% and ≤3%, respectively. In caprock samples, permeability increased by a factor of 3–10 and 1.3, respectively. However, after addition of 5,000 ppm H2S, the permeability of all samples decreased significantly. In the case of CO2+100 ppm H2S, halite, anhydrite, and pyrite precipitation did balance mineral dissolution, causing minimal variation in the permeability of samples.
Standardising HSE Training Through Delphi
Authors: Tamburro Roberta , Forzan Andrea
Published: June 2014

Training is a vital instrument for developing proactive and responsible HSE behaviours. This is why Saipem decided to adopt a method for standardising HSE courses and to share this within the entire Saipem world through the Delphi Project and Portal.

Delphi addresses dispersion and unevenness in HSE training by providing a continuously updated and well-defined list of courses as well as the four guiding (for the trainers) documents per course: a) Specification containing course contents, duration and purpose; b) PowerPoint Presentation of a course (which may also include a video); c) Trainer Manual which stresses a thematic focus and interactivity through role plays; d) Entry Test and Final Test.

Delphi Portal is open to any Saipem employee seeking information on how to manage or attend a HSE course. Course participants can also download training materials and receive updates on activities planned. In short, a top-down approach is supplemented by the bottom-up attitude which drives the development of Delphi.

With course materials prepared beforehand, the Delphi Portal has helped to optimise quality, time and costs of the trainings provided. Contents, materials and knowledge bases, all of which were previously developed and applied locally, are now shared via the Delphi Portal and are an integral part of the company’s global HSE heritage.

Only by sharing knowledge is possible to improve HSE awareness and performance, and only by training employees in a way that will prevent accidents and pollution while at the same time boosting health is possible to ensure highest product quality and profitability.
A New Guideline Document for Temporary Refuge Testing
Authors: Stewart Cameron , Sheikh Shahmeen , Robinson Chris
Published: June 2014

A Temporary Refuge (TR) provides an important component of safety on an offshore platform and most offshore safety cases attribute high availability and survivability of the TR as a key component in establishing an acceptable risk profile for the installation. The UK Health and Safety Executive (HSE) defines the TR as: "a place where personnel can muster safely in an emergency, monitor and assess the developing situation, and either take control action or initiate evacuation".

The Energy Institute (EI) Process Safety Committee (PSC) recently identified that there was no standard testing procedure available to offshore operators which would allow a uniform approach to TR testing and validation. Different operators and test organisations have different testing methods and validation standards which they apply to determine whether a TR provides appropriate protection. The EI therefore commissioned MMI Engineering Ltd (MMI) to help a dedicated PSC Sub-group write a new guideline for the TR integrity testing.

In writing the guideline the group has liaised with a number of offshore operators and test organisations, and reviewed similar guidance documents which are currently used internationally and in related industries (e.g. building services). From this a testing procedure was developed which brings together the best current practices and is bespoke to TRs in an offshore environment; this forms the core of the new guidance
Unintended Consequences of a Promising Safety Management Leading Indicator
Authors: Veley Carl D.
Published: June 2014

Several companies operating in the North Sea and elsewhere have utilized a metric based on a corrective action classification system. Historically, that metric was developed by this author (Veley, 2002) and it initially appeared to be a valuable leading indicator for management purposes. It is a semi-quantitative indication of the strength of corrective actions, and that should be directly linked to the likelihood of problems recurring; the stronger the corrective action the less likely the accident is to repeat. However, after trial applications it became clear that when this metric was used to define performance goals it had unanticipated consequences that cumulatively and insidiously caused more damage than the accidents it was intended to prevent. This paper will discuss those unintended consequences and explain why, in common situations, permanent corrective actions can produce harm, while temporary actions produce improvements. Category Matching is an upgrade of that original metric and eliminates harmful unintended consequences of corrective action classifications used alone.
The Governance Of Acceptability
Authors: Muscio Giuseppe
Published: June 2014

The Tempa Rossa oil field is located in the heart of Basilicata, an agricultural region in the south of Italy, which inhabitants belong to a rural culture set in its ways. The project area lies in the middle of three protected areas (national and regional parks), with consequent challenges in terms of biodiversity conservation and environment protection.

To ensure acceptability of Tempa Rossa project, Total E&P Italia - as a responsible operator of an O&G project - considered that structuring the internal governance of all processes impacting the stakeholders and the territory is a key success factor. More specifically, Total E&P Italia considered necessary to implement an internal process for updating and sharing the activities in real time, in order to prevent and manage problems linked to the social and environmental impact on different stakeholders.

To achieve such objectives, Total E&P Italia set up two internal committees. The Acceptability Technical Group (ATG) ensures that Total E&P Italia guidelines and policies are applied in operational activities and identifies and anticipates potential environmental/social issues in such activities. This is the forum for the representatives of the different Total E&P Italia departments, to discuss and find concrete solutions to the identified problems in order to avoid/reduce "non technical risks" (i.e. suspension of operations, lawsuits, etc.). The mitigation measures plan set in place by the ATG is submitted to the second committee (ASC) for validation. The ASC (Acceptability Steering Committee) is the main internal body in charge of decision-making on environmental/social matters, where strategies are defined and decisions on actions/measures proposed by ATG are taken.
Pttep Health Risk Exposure Score, the HRA Improving Process
Authors: Dusadi-isariyavong Asadang , Thongpradit Amornrat
Published: June 2014

PTT Exploration and Production Public Company Limited (PTTEP), the E&P Company of Thailand has applied the principle of Health Risk Assessment (HRA) to all the operating assets since 2006 by using the Risk Assessment Matrix (RAM) as a tool for risk assessment. The RAM applies the 5 scaled health hazard rating and either 5 scaled occupational exposure limits (OEL), or 5 scaled Frequency of Occurrences (FO), in case hazards are not quantitatively measurable, to define the level of risk into 3 levels. The FO is graded according to how often the condition has been known within the E&P industry. When applied to health condition, the FO could be arbitrary and may not provide the accurate assessment.

In 2012 PTTEP has developed the Health Risk Exposure Score (HRES) system which can replace the FO and OEL in the RAM. The HRES comprises the number of exposed persons, the frequency and exposed duration, the industrial hygiene results, proper occupational health trainings, and the availability of PPE/existing control. Each item is weighed and calculated by three points scale. The result is averaged and distributed into 5 ranges to replace the FO and OEL in RAM.

The HRES is tested against the conventional HRA done within PTTEP in 2012. The result showed significant difference of risk assessment level between the two methods, while the HRES provides more objective assessment and requires less specialist’s opinion in HRA process. Thus the HRA process and finding can become standardized among the PTTEP operating assets.

The PTTEP HRA improving process via the application of HRES will be implemented in both domestic and international assets. The more user friendly software to support the process of HRA is being developed. Then the result of HRA and the feedback from HRA team will be collected for further study as continuous PTTEP HRA process improvement.
Smooth E&P Activities in a Remote Area Having Fragmented/hostile Communities Around - A Case Study Highlighting How an E&P Company Made it a Reality
Authors: Khan Murad Ali
Published: June 2014

Description of the Paper

This paper shares the experiences and results that eni Pakistan had by adopting a ‘Community Investment Management System (CIMS)’ in a developing country -Pakistan. CIMS philosophy is to make ‘Community Relations’ and ‘Community Investment’ management an integral part of the overall business fabric. This system was evolved taking into consideration full E&P activities life cycle in context of indigenous culture, traditions, customs and environment of local communities living around.

Applications

CIMS utilizes the logic of project life cycle, highlighting the importance of stakeholders and company’s risk assessment in ‘Context Analysis’ and adopts the ‘Logical Framework’ approach to plan, manage, monitor and evaluate the interventions.

eni Pakistan has done so by development of people & promoting the indigenous culture, establishing mutually benefitting relations with all stakeholders, fully respecting the territory and the society of which it is an integral part.

Results

Conclusion

Smooth running of E&P activities can be supported by adopting ‘CIMS’ process that can deliver same results anywhere in the world should applied with true spirit and commitment.

Preamble

Over the years E&P Companies around the world have experienced the fact that if local community (living around the areas where E&P activities are conducted) issues are not addressed timely and effectively it gives rise to vulnerable situations that are very challenging to handle and manage. This delayed or no addressing of local community issues aids in development of a culture of distrust among E&P Company and various local community stakeholders. This distrust aggravates the situation and aids in making it a monster to manage. These vulnerable situations sometimes push viable E&P projects into a deadlock scenario with local communities making them unviable. Even in this situation if the interface with local communities are managed by deploying heavy security on ground, the E&P projects remain vulnerable as local community starts behaving in a hostile way with the E&P Company.

Key to transforming this situation into an opportunity is to engage local community into a participatory role by proactive and timely addressing of their real needs and issues. eni Pakistan Ltd has been successful in making this transformation into reality by proactively handling local communities that are living around their Bhit/Bhadra Development Leased Area. This proactive handling of Local Communities have ensured smooth running / continuity of eni Pakistan E&P activities on-ground. Objective of this paper is to share details of how eni Pakistan utilized this opportunity in achieving this success.
Development and Field Trial of a New Exploration HPHT Reservoir Drill-in Fluid
Authors: Færgestad Irene M. , Watson Russell , Strachan Cameron , Johannesen Jorunn
Published: June 2014

The newly developed high-temperature high-pressure (HPHT) exploration oil-based reservoir drill-in fluid (RDF) was specifically designed with formation damage, pressure logging and geochemical analysis in mind. Requirements for a reservoir drill-in fluid that performs well under HPHT conditions, has good pressure log response and is geochemically distinguishable from reservoir fluids were the driving forces for the development of this system. The high-performance, low-damaging system combines several new products. Laboratory results have shown good rheology profiles, tight HPHT fluid loss control, high return permeability values and excellent long-term fluid stability. The system was developed to replace today's standard paraffin systems which occasionally struggle with irregular and too high viscosities with poor fluid stability over time. This occasionally leads to various drilling issues and barite sag problems during low shear or static conditions. Laboratory testing has documented the qualities of the new system, followed by a very successful field trial, where low impact on geochemical tests was obtained. This paper details the development of the fluid, the testing performed to qualify it for the field trial and the successful results from that field trial. Furthermore, the paper also details the high return permeability values and the mechanisms within the system that allow these goals to be achieved. The fluid has properties that make it an extremely strong candidate for reservoir drilling in general.
Some Effects of Size Distribution on Particle Bridging in Lost Circulation and Filtration Tests
Authors: Gatlin Carl , Nemir Charles E.
Published: June 2014

Introduction

A common cure of lost circulation is the introduction of granular bridging agents into the mud system. Many materials, such as ground nut shells, are used for this purpose. If the trouble causing void (fracture, fissure, vug, etc.) is not too large, the granular agent forms a "bridge" across or within the opening. Successively smaller particles in the mud stream then accumulate on and/or within this bridge until normal filtration is finally established. The efficiency of many bridging agents has been studied in the laboratory using various slot testers.

Many investigators have remarked that a granular bridging material should have the proper particle size distribution. With the exception of the broad range specified in the patent of Goins and Nash, there is apparently no definition as to what this distribution should be.

A bridge may be initiated when several particles of lost circulation material lodge against each other in a fracture or other void. Smaller particles then may bridge the openings between the larger, previously bridged particles. This process continues until the voids become quite small and the problem becomes one of filtration. It would seem logical that an optimum particle size distribution exists, i.e., one containing the proper quantity of properly sized material to fill the successively smaller voids of the bridge.

The filtration characteristics of drilling fluids may be subject to a similar analysis. It has been clearly demonstrated by many workers that the filtration behavior of various muds can be altered by particle size control. Slusser, et al, divided filtration into three periods and showed that particle sizes affecting a given period did not necessarily affect other portions of the filtration curve.

An analagous problem is the proper sizing of gravel, liner slots and screen sizes in various sand-exclusion problems. Here the situation is reversed in that a proper "void" size, rather than the size of the bridging agent, is sought.
An Explicit and Continuously Differentiable Flow Equation for Non-Newtonian Fluids in Pipes
Authors: Gjerstad Kristian , Ydstie B. Erik , Time Rune W. , Bjørkevoll Knut S.
Published: June 2014

A simple model approximates Herschel-Bulkley (HB) non-Newtonian fluids in laminar flow in pipes. It is continuously differentiable and explicit in the frictional pressure gradient. Such properties are needed for control, real-time optimization, and prediction in drilling operations. The accuracy of the new model is evaluated by comparing it with a numerical implementation of the implicit HB model and some representative approximations used in the literature. Very little loss in accuracy is experienced compared with the implicit solution.
Case Study—Equivalent-Circulating-Density Management Strategy Solves Lost-Circulation Issues on Complex Salt Diapirs/Paleocene Reservoir
Authors: Murray David , Sanders Mark W. , Houston Kirsty , Hogg Hamish , Wylie Graeme
Published: June 2014

Drilling horizontal infill wells in the Pierce field in the UK Central North Sea (UKCNS) is challenging because of the narrow drilling window caused by depletion in a highly fractured reservoir, which is complicated further by water injection and the proximity of other production wells. Wellbore strengthening was attempted in the reservoir section of Pierce B5 (B5), although, when a pre-existing fracture weakened further by depletion was encountered, losses occurred. During the next 10 days more than 5,000 bbl of nonaqueous fluid (NAF) was lost downhole. During the recovery from the losses event, 15 individual treatments with lost-circulation materials (LCMs) were made. More than 50 t of LCM was used without success; however, the well was stabilized enough to secure the drilled footage and to complete the well.

Two additional horizontal wells in the same field were successfully drilled with a low-equivalent-circulating-density (ECD) management strategy combined with the development of a low-ECD drilling-fluid system and the use of a high-fluid-loss, high-strength (HFHS) pill. The dual problems of barite sag and poor hole cleaning, which can be problematic when reducing ECD through a reduction in fluid rheology, were successfully managed. This low-ECD technique can be applied in other subsea depleted wells in which a narrow drilling window exists.

This paper describes how a detailed analysis of the losses event on Pierce B5 provided an improved understanding of the loss mechanism that resulted in a revised ECD-management strategy. An engineered low-ECD NAF with an HFHS pill, combined with learnings on ECD awareness in the planning and execution phases, mitigated the drilling risks on subsequent wells. This has implications when encountering very large fractures that are difficult to overcome, not only on future Central North Sea wells, but also globally for wells drilled in similar geological settings.
Maturing Collaboration in Intelligent Energy: Challenging the Conventional Wisdom of Collaboration Environments
Authors: Kuhn Michael
Published: June 2014

Maturing Collaboration in Intelligent Energy: Challenging the conventional wisdom of Collaboration Environments This paper explains why the conventional wisdom of collaboration environments is out of date with the current landscape of technology enablers and should be aligned with the shifting landscape of how people collaborate.

To date, the collaboration has focused on enabling team collaboration. The focus going forward should be to enable the Digital Engineer and move away from designing collaboration environments around structured team processes, as this actually limits the value of the collaboration environment. After years of significant investment in collaboration technology, process improvements and change management, many organizations have not captured the transformational value that was promised with such programs. Common themes have emerged from industry case studies to better understand the root causes associated.

A Collaboration Maturity Model was introduced in a previous paper (Gilman, Kuhn 2012) to outline the current state of collaboration and potential future areas of innovation. The underlying enablers of collaboration will be discussed such as technology; environment, process and organization that have shifted to suggest the traditional team based collaboration environments do not fit the expectations of today’s Digital Engineer. Many of the traditional collaboration environment designs were focused specifically on enabling teams to work together when information could not be easily shared and communication across distance was not seamless.

Today there is a clear opportunity to re-think collaboration environments to better meet the work practices of next generation workers.
Development and Implementation of an Effective Operator Interface System in the UAE
Authors: Legg Corbett , Kirkman Matthew , Al Gaith Saud , Ali Kamal , Tysseland Trond , Dalloul Naseem
Published: June 2014

ADMA-OPCO have maintained a consistent Operator Interface System (OIS) in the control rooms over recent decades. The need to move to a modern interface compliant with current industry best practice for three major new field projects was recognized in 2009 in the new projects specifications. This addresses both safety and efficiency while recognizing the increased level of instrumentation on the newer facilities and the expected diversity in our future workforce.

Developing a new OIS approach required working with vendors to ensure the ability to technically deliver the new design regardless of vendor. There was also a review of current practices by other international operators. The new design addresses past OIS deficiencies in the graphics imposed by limitations of older systems used to monitor, control, and respond to events in the process. Those deficiencies were in colour, content, layout, and difficulty in the maintenance of operational settings. Much time was spent in control rooms eliciting input from current operators, both experienced as well as recent hires.

The new specification utilizes pattern recognition techniques to easily verify a stable process state from massive amounts of data and addresses the appropriate use of colour and patterns to quickly direct attention to areas of concern. This OIS emphasizes a logical and consistent schematic layout based on process and operational divisions. The operator adjusts target values and alert limits allowing monitoring and maintaining the process in an optimal state before supervisory set alarm limits are reached.

Prior to implementation in the new fields, the OIS was implemented as a pilot in parallel with the existing system on a portion of the Das Island processing facility. This was to capture lessons and input from operators using the new system before finalising the new fields design with an alternate vendor. In parallel, a campaign was undertaken to eliminate nuisance alarms and to adjust instrument ranges and supervisory alarm limits to more appropriate levels.

The evolution of the operating design philosophy and the process for design, engagement, and implementation from those activities through the initial pilot system start up are discussed. The system described below is now formalized as an ADMA standard procedure, and will be implemented by the Main Automation Contractor on ADMA New Fields.
Building Neural-Network-Based Models Using Nodal and Time-Series Analysis for Short-Term Production Forecasting
Authors: Rebeschini J.. , Querales M.. , Carvajal G. A. , Villamizar M.. , Md Adnan F.. , Rodriguez J.. , Knabe S.. , Rivas F.. , Saputelli L.. , Al-Jasmi A.. , Nasr H.. , Goel H. K.
Published: June 2014

Implementing asset-wide intelligent digital oilfield (iDOF) solutions, aiming to optimize oil and gas production system in an "intelligent" manner, requires integrating concepts from different disciplines, such as artificial intelligence. Neural network- (NN-) based models are a form of artificial intelligence, which is a branch of computer science that generates mathematical models that can be "trained" to determine relationships between inputs and outputs, recognize patterns, and perform reliable short-term predictions. NN models using real-time data are proven tools for short-term well production forecasting with acceptable accuracy.

An oilfield is a hostile environment for even the most robust instrumentation. As a result, technical outages or anomalies can result in lost or poor quality data. Experience shows that many samples in a real-time database are frozen, missing, corrupted, or incorrect. This fact represents the biggest challenge to creating a reliable NN model. However, the models can be trained to correct or estimate missing real-time data. This paper presents a case study where nodal analysis was used to populate missing data used to train NN model, thus improving the reliability of the model. Because nodal analysis is not suitable for prediction, time-series analysis was used to assess the impact of historical events, and operational conditions were used to forecast trends. The NN trained with nodal analysis can cover a wide variability spectrum and, when trained with a time-lapse series, can predict short-term (30-day) production scenarios by changing highly correlated parameters, such as tubing head pressure (THP) or frequency (Freq).

This paper describes training NNs using nodal analysis and time-series analysis to predict short-term water cut (WC or BS&W) and liquid flow rate. This technique was applied in over 20 wells with electronic submersible pumps (ESPs) and gas lifts (GLs). The NNs made robust estimates of production rate and an acceptable prediction trend for 30 days, even when confronted with flow meter instrumentation failure, lost signals, and out-of-calibration instruments. Hence, the NN served as a "virtual meter," providing instantaneous and accurate estimation of production data.
South Oman Progressing Cavity Pumps Continuous Control Pressure Setup
Authors: Al Mahrooqi Salim , Velazco Conny , Vargas Luis , Sanchez Carlos
Published: June 2014

In fields with large number of wells, any improvement in the monitoring and production optimization processes can have a significant impact in the overall field performance.

With this vision, in April 2012, a new tool for optimizing PCP wells was introduced in PetroleumDevelopments Oman (PDO) as a trial. This new setup was based on enabling Pressure Control Setup (PCS) control that would allow the PCP speed to be adjusted based on well/reservoir potential assessedby a measurement from a downhole pressure gauge. The downhole pressure value is used as target value for this PCS controller.

This paper describes the main benefits about implement a PCS loop after implementation in two pilotPCP wells based on intake pressure. This setup enhances well operation by timely maximizing production and/or accelerating production optimization, protecting the pump against running dry and protecting the reservoir should a lower pressure limit be reached, e.g.a limit that can onset sand production or water coning.

An additional benefit of using this tool is the reduction of the required manpower which also reduces the HSE exposure due to less mobilization and traveling time, for the well optimization.
Real-Time Optimization of a maturing North Sea Gas Asset with Production Constraints
Authors: Van Der Linden Ruud , Busking Tom
Published: June 2014

As gas and oil fields mature their operation becomes increasingly more complex, due to complex process dynamics, like slugging, gas coning, water breakthrough, salt or hydrate deposition. Moreover these phenomena also lead to production constraints in the upstream facilities. This complexity asks for operator support in how to optimally operate such an asset.

In this paper we explore how, based on physical models of reservoirs, wells and top side separation and compression equipment, real-time optimization may be used in optimal operation of a maturing asset showing complex dynamic behavior and top side compressor constraints. In a joint industry project of Wintershall, GDF, EBN, Siemens and TNO the applicability of Real-Time Optimization is explored.

Real-time optimization will be demonstrated on a maturing North Sea off-shore gas production asset consisting of eight wells and two separator and compression trains.

The current results show how the optimization problem has been defined and implemented in a real-time architecture. First results are shown realizing the gas production set point and minimizing compressor power, while the production of individual wells suffer from degrading performance and (unplanned) shut-ins.

The optimizer computes how the production must be dynamically distributed over the wells and how the compressor trains must be operated.

Dynamic optimization strategies have been exploited successfully in downstream operations. A similar development is happening in upstream industry, while having to cope with the higher uncertainties typically present in upstream processes. As the paper shows Dynamic Optimization may lead to large benefits in Real-Time Operation of upstream production facilities.
Smart Mobile Worker- Bringing our Facilities closer!
Authors: Van Dijk Jaap E.
Published: June 2014

Today, production of oil and gas is faced by many challenges as the major sources become depleted. This leads into the exploitation of remote and inhospitable fields of deep water reservoirs, frigid arctic climates and for PDO hot dusty deserts. To maintain the highest possible production at these harsh operating environments, whilst meeting the challenges of personnel safety, lower operating costs and preserve environmental protection, forefront technologies are required to explore new ways of reducing the need of people to be in hazardous areas, and improve their productivity, safety and efficiency while onsite.

Smart Mobile Worker (SMW) provides the capability of "Remote-expert" mode between site staff and technical experts where experts anywhere in the world can be easily and immediately confronted with problems. Further, SMW introduces a new step change by delivering real time information to workers anywhere on site enabling them to make more informed timely decisions by bringing the right data resources and knowledge anywhere onsite.

The SMW concept is an essential shift towards realization of smarter sites by increasing field workers efficiency & productivity, and improving HSSE to achieve Goal Zero. Primary focus will be on Smart Sites because remote work is fundamental driver here.

This Manuscript describes a first pilot in the field where the focus was on SMW 1 Audio & Video functionality. It explains the use of this new technology in an operational environment where by with a minimum investment of time and money has delivered 50% improved production on one specific well. Also a significant improvement in efficientcy and reduction of HSE exposure was recorded. To underline SMW benefits we can show a trial video or live demo depending on some technical boundaries at the conference location.
Achieving Digital Oilfield Competency
Authors: Pickering J. G. , Sengupta S..
Published: June 2014

Many oil and gas operators now see Digital Oilfield as a mature technology and yet there is still a broad spectrum of knowledge across the industry about what it is and how to derive a good return on investment. Much has been said about developing the "People", "Process" and "Technology" sectors in parallel but even the most enthusiastic Digital Oilfield adopters would admit that it is the "People" sector that gives them the greatest challenge. The big problem is how you engage the entire workforce, from senior managers to field technicians, in a technology with which only a few are really "hands on". Many companies have chosen to ignore this problem and yet the entire workforce must be engaged, as the senior managers will be the financial decision makers and the field technicians will be the enablers of real-time data.

This paper describes a novel approach to training and the achievement of real Digital Oilfield competency. It reviews typical delegate responses to more traditional classroom learning versus innovative styles based on learning through enjoyment, including participation in business games and role playing.

The authors have experience of different training styles but have found that creating a less formal atmosphere with a high level of personal engagement and active participation delivers the best results. They are now proposing an "a la carte" approach to training, through a range of course modules that may be tailored to the requirements of the delegates. So, in effect, the delegates choose up front what they want to learn. The course must deliver a foundational knowledge of Digital Oilfield but may have a technical, commercial or even a cultural focus to satisfy the requirements of the delegates, who must be matched carefully to ensure that they have the same training expectations.