bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Approach to Sand Management in Matured Field Operations
Authors: Ruslan M. , Lee P. Y. 
Published: May 2015

Abstract
The integrated approach to sand management is crucial to address the sanding risk in the producers and injectors in the North Sea mature field. The concepts incorporates the LEAN approach and developed with major focus on the rehabilitation of mature fields where each barrel of oil counts and uncertainty, both technical and economical, are becoming more challenging at industry level. High decline in productivity and increased operational challenges are common issues for mature fields.
The sand management is divided into 4 major live phases which are sand prediction, sand prevention, sand production and evaluation/feedback. Each stage is mapped and associated with field redevelopment plan, project management control level, the time cycle (short: operation efficiency, medium: production optimization and long: reservoir management), digital oilfield, roles and responsibilities, enabling technologies and fine-tuned workflows.
History case including the utilization of dynamic multiphase flow simulator to fully understand the water hammer sanding behavior and the remedial job enabling technologies will be discussed briefly to demonstrate the utilization of the integrated sand management approach.
The paper will also highlight the key challenges to ensure that the sand management is a continuous improvement effort that is suitable for high level planning and yet practical for day to day operation.
The sand management has been developed based on multidisciplinary approach, lessons learnt and best practices acquired in mature field rehabilitation projects with major consideration to maximize the recoverable reserves and optimize the matured asset added value creation.
Swellable Packer Fluids Designed for Zonal Isolation in Openhole Completions
Authors: Offenbacher Matt , Gadiyar Bala , Messler Dave , Krishnamoorthy Suba-Rao , Abasher Doha 
Published: May 2015

Abstract
A weighted, all-oil fluid system was developed to activate oil-swell packers and maintain compatibility with water-based filtercakes. This fluid system has enabled the successful installation of multiple openhole gravel pack completions to date.
Traditionally, base oils, such as diesel, serve as activating fluids. The low density of the base oil risks compromising well control and/or borehole stability. There are products available to viscosify the base oil and suspend weight material for some applications, but jobs most require special shearing equipment operating at temperatures above safe limits for base oil. Other products are required at significant concentrations that risk adverse reactions with the water-based filtercake and filtrate. Invert emulsion systems offer greater density and viscosity, but they are incompatible with the water-based filtercakes, risking formation damage.
This new fluid system utilizes a new viscosifying agent that easily mixes using rig equipment along with an acid-soluble, treated weight material to maintain a dispersion in oil. All of the products are micronized to reduce any risk of plugging downhole completion equipment. The all-oil system is spotted in the open hole, allowing the swell packers to expand. The system may either remain in the wellbore to flow back with production or circulate out of the wellbore prior to gravel packing. Flexibility in additive concentrations aids to effectively displacing the fluid in and out of the well.
This paper discusses the development process of this all-oil system in the laboratory and the challenges overcome to deliver a rig-practical solution. A review of field planning and execution is included for the initial wells employing the system.
Bursting the Skin Bubble – Decoupling Formation Damage from Skin in Complex Well Geometries
Authors: Byrne Michael , McPhee Colin , Lemanczyk Rick 
Published: May 2015

Abstract
The dimensionless parameter “skin” is commonly used to describe actual well performance with reference to an ideal case, and a number of analytical correlations have been derived over the years to account for the effect on well productivity caused by well geometry, completion design, formation damage and production rate. In a previous publication (Byrne and McPhee, 2012) we outlined the case for reducing the industry's reliance on analytical skin factors for well performance evaluation, particularly since the various “components” of skin, or “pseudo skins,” are often lumped together, and their interaction and interrelationship are often confused.
The concept of well design without recourse to a “total” or lumped skin parameter merits further description. For example, whilst hydraulic fractures may present an opportunity for significant enhancement in well performance, the fact remains that the fractured well itself, while an improvement on the unfractured case, may still not be producing at an optimum rate, especially if there is damage in the formation, at the fracture face or in the proppant pack. An overall total “negative skin,” which arises naturally when characterising the fractured well productivity with reference to an ideal vertical, unfractured well, can actually mask the true well potential. There is a tendency to believe that performance has been optimised but this is simply not the case.
If the geometry of the wellbore, including the completion and induced fractures, are relatively well understood and can be described then the well productivity can be modelled based on the system architecture without the need to compare it to some hypothetical simpler geometry. The quantity and location of formation damage can then be imposed on the model to determine the impact of damage in the fracture, at the fracture face and deeper within the formation.
This paper will illustrate how an indiscriminate use of skin factors can lead to sub-optimal well design and resulting performance prediction, and how this can be improved by representing the real system geometry as rigorously as possible. Decoupling formation damage from its association with other pseudo skins enables a proper description of the impact of damage and its contribution to well performance.
The Effect of pH on Silicate Scaling
Authors: Sazali R. A. , Sorbie K. S. , Boak L. S. 
Published: May 2015

Abstract
Silicate scaling during high pH Alkaline Surfactant Polymer (ASP) flooding is known to adversely affect oil production. The silicate scale occurs as a result of the dissolution of silicates under high pH conditions and where the fluids subsequently flow into a region of lower pH where they then precipitate. The precipitation of magnesium silicate strongly depends on solution pH and temperature and is affected by the kinetics of the silicate scaling reaction.
In this paper, the effect of pH on the stoichiometry and morphology of silicate scale is studied. A range of spectroscopic techniques, including Environmental Scanning Electron Microscope/ Energy Dispersive X-Ray Spectroscopy (ESEM/EDX), Fourier Transform Infrared (FTIR) and X-Ray Powder Diffraction (XRD) are applied in order to analyse the precipitated silicate scales in the laboratory. These spectroscopic techniques, when used along with reference sample spectra, yield a number of interpretive clues as to the nature of the silicate precipitates which are formed. The further analysis of the solution and precipitate by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and ESEM/EDX also gave complementary information which was consistent with the results obtained from the other spectral methods above.
The approach used in this work has enabled us to establish the composition and morphology of the silicate scales formed under different pH condition. There is relationship between the pH conditions and the compounds appearing in the precipitate. Results obtained can be used to help determine the most appropriate type of scale inhibitor for silicate scale mitigation in future.
Understanding Perforation Geometry Influence on Flow Performance Using CFD
Authors: Allison Simon , Löhken Jörn , Nelis Liam Mc , Djayapertapa Lesmana , Byrne Michael , Watson Ken , Clarke Alistair 
Published: May 2015

Abstract
Perforations are required to establish effective hydraulic communication between the wellbore and the surrounding formation. An often considered key attribute is to achieve maximum penetration, providing an effective flow path by extending through the near-wellbore damaged region, penetrating undamaged reservoir beyond.
The challenge is always to design the perforation system to maximise flow efficiency. In the majority of instances deeper penetration is a key design parameter, but penetration is affected not only by the shaped charge, but also critically by rock strength and stress effects. Therefore, perhaps of greater importance are perforations that are both clean and less damaged, providing a more effective connection to the reservoir, whilst maintaining maximum penetration.
Much has been done to enhance perforation efficiency through the development of dynamic underbalance systems and, where appropriate, the application of reactive charge technology. However, little has been done to explore possible benefits resulting from significant changes in perforation geometry, beyond conventional premium system design.
This paper provides a detailed insight into a comprehensive research and development study, following the conclusions obtained for a new convergent perforation system. The system is optimised through harnessed shock-wave energy, achieved by focusing charge groups at a fixed point within the reservoir.
A rigorous section IV test programme was conducted to evaluate the potential flow performance enhancement for such a perforation system. Lab results highlighted a &gt;15% increase in the tested productivity ratio, compared directly to standard system shots, executed under identical conditions.
API-19b Section IV test data validation was carried out using Computation Fluid Dynamics (CFD). A key objective was to match the lab flow performance data, replicating boundary conditions and perforation geometry within each model. CFD modelling enabled further detailed assessment of key relevant parameters influencing improved flow performance, i.e. crushed zone damage and improved channel geometry effects.
Furthermore, CFD was used effectively to model a series of short radial well models, using each matched perforation geometry, comparing the convergent perforation system against the standard HSD system. These models provided further evaluation of key performance influencing factors such as shot arrangement and phasing effects.
In conclusion, the study has shown, through various levels of verification, adopting a convergent perforation approach to gun system design, can enhance perforation flow efficiency through geometry improvement. CFD modelling also showing, within a radial wellbore arrangement, such a system is capable of improving flow performance by as much as 50%.
Graded Proppant Injection into Coal Seam Gas and Shale Gas Reservoirs for Well Stimulation
Authors: Keshavarz Alireza , Badalyan Alexander , Carageorgos Themis , Bedrikovetsky Pavel , Johnson Ray 
Published: May 2015

Abstract
Low productivity indices are observed in many moderate-to low-permeability coal bed methane (CBM) and shale gas (SG) reservoirs due to low aperture and poor connectivity of natural cleats.
A method is proposed for injection of graded proppant particles into a cleat system below the fracturing pressure to keep coal cleats and shale fractures open during water-gas production. Graded proppant injection in CBM and SG reservoirs can: stimulate a stress sensitive cleat system below the fracturing pressure; enhance fracturing treatment by invading cleats, lowering fluid leak-off, and maintaining aperture during production; and provide a periodic or remedial treatment to counter effective stress on the cleats improving production by maintaining cleat aperture.
Laboratory tests on bituminous coal core flooding with water under increasing pore pressure with graded proppant injection at the maximum pore pressure (minimum effective stress) have been carried out at different ionic strengths and high pH of the injected water. Proppant particles penetrate deeper into coal matrix at low ionic strength of injected water corresponding to electrostatic particle-particle and particle-coal repulsion. No particle agglomeration and formation of particle-formed cake at the entrance of coal cleats are observed at these conditions. Coal permeability increases by about 2.2 times as the result of a single-sized small particle injection. Followed injection of larger particles leads to a greater enhancement of coal core permeability. An overall increase of coal core permeability after graded proppant injection is about 2.7 times.
The proposed method can significantly increase very low productivity index in stress sensitive coals and shales without hydraulic fracturing. It can be also used as a non-damaging leak-off additive during hydraulic fracturing stimulation treatments and to aid long-term conductivity.
A Novel Method for Optimal Perforation Design
Authors: Pasztor Adam , Kosztin Bela 
Published: May 2015

Abstract
In case of hydrocarbon production optimization it is essential to know the relationship between the inflow rate and the performance of a perforated production well. It describes the flow rate at the bottom of the well in function of the applied drawdown pressure. The process is strongly influenced by the perforation parameters, formation characteristics and the properties of produced reservoir fluids. The correct calculation gives optimum perforation design and optimized fluid production.
In a cased and perforated well, the reservoir fluids flow through the perforation channels before entering into the well. Thus the parameters of the perforations like penetration depth, phase angle, length of perforated interval, entry hole diameter, average radius of perforation channels and the radius of the crushed zone, etc. have significant impact on the relationship between the flow rate and the well performance. The very first examinations on this phenomenon dates back to the mid 70's. Several equations have been developed to describe the pressure drop through the perforation. However, numerous assumptions have been applied in the derivations of these equations, which have resulted significant loss in accuracy. A new calculating method has been derived and presented in this paper by applying the most accepted methods, i.e. the equation of McLeod and the one of Tariq and Karakas.
The new complex method takes all of the perforation parameters and their effects into account to provide more accurate results. The effect of different perforation parameters on the productivity of oil and gas producing wells are also demonstrated.
As this method takes all the effects of perforation parameters into consideration, different perforation designs can easily be compared and optimized. The great advantage of this method is that it points out the difference between effects regarding the inflow performance of oil and gas wells.
Molecular Weight Effects in Polymeric Scale Inhibitor Precipitation Squeeze Treatments
Authors: Farooqui N. M. , Sorbie K. S. , Boak L. S. 
Published: May 2015

Abstract
The most common scale inhibitors (SI) in the oil industry are polymeric and phosphonate species which are widely used to prevent calcium carbonate and barium sulphate scale formation, and these SIs may be applied in the field in downhole “squeeze” treatments. This paper focuses on the underlying mechanisms associated with polymeric precipitation squeeze treatments, where the polymer is precipitated in situ to enhance its retention in the formation and thus extend squeeze lifetime. Three polymeric SIs of similar structure are studied in this work, PPCA, SPPCA and PFC (full names in paper). Inhibition efficiency (IE) results are presented and analysed in terms of the molecular weight distributions (MWD) of the these polymers. IE and MWD results are shown for each for these polymers “as supplied” (the stock solution) and also for the “precipitated” and “supernatant” fractions, as would occur in a precipitation squeeze treatment. For PPCA, this precipitate has been shown to be a calcium complex of the polymer with stoichiometry, PPCA-Can (n ≈ 30). It is shown that the precipitated forms of PPCA and SPPCA are more efficient at inhibiting barite than either the stock or the supernatant due to the fact that they preferentially contain the larger molecular weight species, which increased the IE. However, the corresponding inhibition efficiency results for the PFC copolymer are rather different to those for SPPCA and PPCA and this is described in the paper.
Further studies of the solubility of the PPCA-Can complex in successive samples of fresh brine suggest a “stripping model” for the dissolution/solubility of this complex, in which the lower molecular weight (MW) species are preferentially dissolved into supernatant brine until some equilibrium is reached. This, in turn, results in the original precipitate being enriched in higher MW species which are less soluble than the lower MW species. This model of dissolution is very different from a “solubility product” model as would describe a sparingly soluble mineral salt. This should now be taken into account in the modeling of polymeric SI precipitation squeeze processes, and it also has implications for the laboratory testing of polymeric SIs for application in precipitation squeeze treatments.
An Advanced Proppant Based Fracture Stimulation Treatment on an Extended Reach Well in the Southern North Sea Utilising a New Purpose Built Vessel: a Case Study
Authors: Souza L. , Oliveira E. , Angheloiu I. , Barry J. Du , Leigh H. , Austin S. , Shaoul J. , Spitzer W. 
Published: May 2015

Abstract
An extended-reach, S-shaped appraisal/development well drilled from a platform to prove up and drain a field extension in a Rotliegendes sandstone reservoir has been hydraulically fractured with a proppant-based stimulation treatment. The hydraulic fracture was a means to optimise the production rate and involved an injectivity test followed by a main treatment.
The hydraulic fracture was performed utilising a stimulation vessel constructed in 2013 that is equipped to perform large-scale acid and proppant hydraulic fracturing and acid matrix stimulation treatments. This treatment was the first massive proppant hydraulic fracturing operation performed by the vessel. Prior to this operation, the vessel had been used to perform numerous acid-based stimulation operations.
A total of 365.3 metric tonnes (730,536 lb) of resin-coated intermediate strength proppant was placed in the fracture, which is thought to be the largest single fracture treatment ever pumped in this particular national sector of the southern North Sea. A tip-screenout design was successfully used to achieve a high average proppant concentration of 23 kg per square metre (4.7 lb/ft2), which equates to an average propped width of 1.3 cm (0.51 in). The large width was needed to achieve sufficient fracture conductivity for the expected reservoir permeability and to minimize convergent flow pressure drop in the fracture, due to the short perforated interval that was used. A very short perforated interval was used to minimize the risk of near-wellbore problems, due to the well deviation of 40 degrees in the payzone. This approach was successful, as the treatment was pumped as per program with no vessel NPT and no HSE incidents.
Lessons learned included optimisation of perforating operations, methods to better optimise initiation of proppant flow to the blender, rationalising data sources, and effective use of equipment redundancy to ensure zero NPT.
New Alternatives in Conformance Control: Nanosilica and Liquid Polymer Aided Silicate Technology
Authors: Lakatos I. J. , Lakatos-Szabo J. , Szentes G. , Vago A. , Karaffa Zs. , Bodi T. 
Published: May 2015

Abstract
The main objective of the laboratory and field studies was to develop an efficient and flexible reservoir conformance control (RCC) technology through improvement of the standard silicate method with joint application of "liquid” polymer and nanoparticle (silica) suspension. Similarly, the important idea was to simplify the surface facilities and reduce cost of chemicals, treatment time, and human force. The laboratory studies focused on laser particle sizing, dissolution kinetics, colloid chemical, rheological, gelation kinetics and setting time, and flow properties of polymer and nanosilica containing silicate gel methods in porous media (sandstone). Based on the experimental findings, it was found that “liquid” polymers and “liquid” nanosilica readily and rapidly dissolve and mix in water, and the solutions are free of microgels and the mechanical entrapment was minimal even in low permeable sandstone cores. In addition, they decreased significantly the surface tension and interfacial tension.
It was proved that such “liquid” additives provide unprecedented flexibility to the technology and the enhanced methods may be attained with labor and expenditure effective way. The main effect of polymer was to stabilize the silicate gel against syneresis (spontaneous fracturing) and formed a secondary network in gel and that fact provided more thermal stability of gel. The nanosilica beneficially influenced the gelation kinetics of polymer containing silicate solutions. The main effect could be traced back to advanced nucleation of gel formation. Additional positive effect of nanoparticles is that its presence in the reaction mixture makes more flexible the pH control in both the bulk phase and in porous media. The extra beneficial properties of “liquid” polymers and nanomaterials in all oilfield chemical applications may significantly contribute to improvement of standard technologies; meanwhile the surface facilities can be simplified, or completely eliminated (e.g. the “liquid” polymer and nanosilica can be directly injected to basics sodium silicate solution at wellhead).
Earlier, the “liquid” polymer was successfully applied in water shutoff in Oman. Recently, a new field programs is running in Hungary using silicate/polymer solution with nanoparticle (silica) fillers. The paper details the “from laboratory to field” activities, and demonstrates the superiority of the novel concept. The successful field pilots, the join application “liquid” polymers, and nanosilica may open new vistas in reservoir conformance control.