bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perforation Cleanup via Dynamic Underbalance: New Understandings
Authors: Grove B. , Harvey J. , Zhan L. 
Published: June 2011

Abstract
Dynamic Underbalance perforating is a completion technique which uses a perforating system engineered to create a rapid underbalance immediately upon formation perforation. This technique – properly applied – improves well deliverability by effectively cleaning the newly-created perforation tunnels, regardless of initial static pressure conditions (overbalanced, underbalanced, or balanced).
Over the past 3 years, we have conducted dozens of perforate-and-flow laboratory experiments, carefully controlling and measuring wellbore transients, and measuring post-shot productivities. Our results indicate that the cleanup mechanisms are more involved than conventionally understood. We observed that a dominant mechanism of dynamic perforation cleanup is the increase in effective perforation length. We also confirmed previous findings that DUB perforating increases tunnel diameter, while reducing the thickness of the "crushed zone" of impaired permeability, which surrounds each tunnel. Although these processes have been mentioned in general terms previously, conventional models typically simplify things by reducing perforation cleanup to the enhancement of crushed zone permeability. Though this simplification has offered a convenient means of interpreting lab data, it can yield misleading results when applied downhole.
While increasing crushed zone permeability does indeed improve the productivity of real wells, the additional processes of enlarging tunnel diameter and reducing crushed zone thickness improve productivity further. Increasing the effective tunnel length provides yet another means of productivity gain, and under most circumstances is the dominant beneficial effect. We present productivity predictions of various downhole scenarios to quantify these newly-recognized effects.
These findings suggest the performance differential (between DUB and non-DUB techniques) at downhole conditions can be far greater than previously recognized.
Translating Perforating Laboratory Results to the Downhole Environment
Authors: Grove B. , Harvey J. , Zhan L. , Atwood D. 
Published: June 2011

Abstract
Perforating laboratory experiments are being conducted more frequently in recent years. In some instances, the goal is to qualitatively compare multiple candidate perforating techniques. In others, the goal is to obtain quantitative insight into likely flow performance in the field. Although the laboratory will never perfectly replicate the downhole environment, it can yield useful results which – if properly interpreted – can enable informed prediction of downhole flow performance.
A traditional flow lab experiment (along the lines of API RP-19B Section 4) yields many key results, four of which are required inputs to downhole inflow simulators. These are perforation tunnel length and diameter, and crushed zone thickness and permeability. In the case of natural completions, these parameters (in addition to other system and wellbore parameters), dictate the skin and ultimate flow performance of the completion.
Crushed zone permeability is typically inferred from core flow efficiency (CFE) and an assumed crushed zone thickness. As traditionally applied, this technique can yield values which are not accurate, and more significantly can produce misleading predictions of downhole performance.
To address this, we have developed new methods for both measuring and interpreting CFE. The new measurement technique yields CFE values which are more meaningful and relevant. The new interpretation technique provides a consistent method of translating CFE to crushed zone permeability, and is capable of accounting for the effect of partially plugged tunnels. This work clarifies and improves the link between lab and field performance of perforators, with the ultimate goal of increasing the value of downhole inflow performance predictions.
While other work is ongoing to challenge the framework of the conventional skin models, the present paper accepts these models as a premise. This work simply presents a coherent methodology of interpreting laboratory data, with the intent of generating the required inputs for skin models as they currently are. Furthermore, it is recommended that this workflow be considered for inclusion in any revisions to Section 4 testing protocol.
Size-Exclusion Particle Capture During Mono-Dispersed Suspension Flow in Porous Media
Authors: O'Reilly D. I. , Bedrikovetsky P. , Lee K. , Zakaria N. 
Published: June 2011

Abstract
In this work, we develop a new analytical solution for the problem of deep bed filtration under size-exclusion dominated particle capture. An uspcaled stochastic micro model has been derived that models individual particle-pore interactions. The solution is based upon mono-dispersed suspension injection into a medium with a known pore throat distribution. Ultimately, the model can be used for matching with laboratory corefloods, simulation of permeability decline or expected tracer breakthrough.
Size-exclusion particle capture during suspension transport in porous media takes place during drilling fluid penetration into oil bearing formations, sand production and the injection of poorly treated water. Straining particle capture can dominate over the particle attraction in cases of produced water injection, injection of produced water from aquifers, fines production in fractured wells and gravel packed horizontal wells. Deep bed filtration contributes highly to the problem of formation damage.
Planning and design of the above-mentioned oil production processes is based on reliable mathematical modeling. If compared with previous population balance models for the general case of particle capture, the current work discusses a particular case of pure straining. We show that in the case of particle-grain and particle-particle repulsion, the particles cannot be strained in pores larger than the particle size. The particles can be captured in thin pores only. These considerations change the expression for capture rate in the basic population balance model. In order to validate the proposed model by comparison with laboratory tests, we found a travelling wave solution. The comparison with 2 sets of laboratory data showed good agreement, which validated the proposed model.
The new solution has broad application to the petroleum industry. The developed model can be applied for: (1) Particle sizing for drilling fluids, (2) Log interpretation of filtrate penetration into the formation, (3) Design of injected water treatment and (4) The design of gravel packs to minimise fines production and formation damage.
Controlled Wellbore Implosions Show that Not All Damage is Bad – A New Technique to Increase Production from Damaged Wells
Authors: Al Busaidy Adil , Zaouali Zouhir , Baumann Carlos Erik , Vegliante Enzo 
Published: June 2011

Abstract
Near wellbore damage is often blamed for many production problems, it can manifest itself in many ways and is caused by almost anything that disturbs the formation; even producing hydrocarbons can lead to near wellbore damage. Knowing where the damage is and how it was produced can help prevent new occurrences, but oftentimes prevention is not possible. Perforation damage is one kind of damage that cannot be prevented; because the objective of perforating is to damage the formation by creating a tunnel as large and as deep as possible.
A new technique of consisting of producing controlled implosions constitutes the most effective way of removing perforation and other types of near wellbore damage, and this technique lends itself to provide quantitative values of well damage removal. This paper discusses how this new technique was developed, from concept and modeling to its effectiveness in the field as demonstrated by a number of jobs on wells with different types of damage. The results are extremely encouraging; in some wells production has increased by as much as three to four times, this production increase is sustained and the rate at which well formation damage occurs is significantly lower.
This paper presents field experiments conducted on four wells in the Libyan Desert, including logging data based on state of the art measurements, and giving new insights into near wellbore damage. Strategies are recommended to combat the effects of common near wellbore damage mechanisms and to address their root causes. These findings opened a debate that challenges some aspects of industry accepted perforation techniques, and presents conclusive evidence that some well damage is in fact beneficial.
Laboratory Evaluation of Organic Water Shut-off Gelling System for Carbonate Formations
Authors: Al-Anazi M. S. , Al-Mutairi S. H. , Al-Khaldi M. H. , Al-Zahrani A. A. , Al-Yami I. S. , Gurmen M. N. 
Published: June 2011

Abstract
Water production can reduce or block oil and gas production rates. In addition, the lifting, handling, and disposal of produced water negatively impact the hydrocarbon production economics. Among several techniques for water control, crosslinked polymer systems are the most effective for certain water shut-off projects. The objective of this paper is to assess the effectiveness of crosslinked polymer system for water control applications in carbonate formations and present its optimal formulation.
This paper presents a detailed lab testing of a cross-linked polymer system. The system includes a gelling agent, primary and secondary crosslinkers and an acidic activator. The evaluation covered extreme concentrations of all components, temperatures up to 212°F, differential pressures up to 1,500 psi, actual field water salinity, wide range of permeability, and extended testing time up to three months. Core-flood experiments along with Computerized Tomography Scanning and Environmental Scanning Electron Microscopy were used to assess the sweep efficiency and the strength of the gel inside the core plugs. Losses of active ingredients from effluent samples were measured using Thermal Gravimetric Analyzer. Results of carbonate core plugs were compared with that of Berea sandstone. Strength of the gel at different cross-linker and polymer concentrations was monitored using sealed glass ampoules. Gelation times were measured using bottle tests and rotational viscometers.
Extreme vertices design was used to optimize the experimental work and mixture triangle was used to represent the final results. An optimal gelling system with controlled gelation time and maximum performance was attained for the targeted formation at 212°F. It was found that the gelation time was affected by the three main components of the gelling system. The acetic acid-based activator was found to have the highest effect on the gelation time. However, this activator was not effective when the gelling system was tested in carbonate core plugs. A major effort of this work was to develop alternative strategies for the ineffectiveness of acidic activator in carbonaceous formations.
Sand Control Completions for Ormen Lange Big-Bore, High-Rate Gas Development, Evaluation of Concept Selection, Qualification, Execution and Well Performance
Authors: van Kranenburg A. , Twycross J. , Combe C. , Hals K. 
Published: June 2011

Abstract
Ormen Lange is the second-largest gas field in Norway, currently providing 20% of the domestic gas consumption for the UK. As one of the world's largest subsea big-bore gas wells - with production rates up to 350 MMscf/d per well, a 120-km tieback to shore, subzero seabed temperatures and a design life of more than 30 years - these wells provide unique technical challenges. Due to the low reservoir rock strength, high velocities and the life expectancy of these wells, sand control was identified as a prerequisite from day one.
This paper clarifies the logic of the selected sand control method and describes the extensive testing required to qualify the sand control hardware and associated completion fluids for the expected operating conditions. The execution of thirteen successful sand control completion installations will be discussed, including both ends of the success spectrum, and well performance will be covered.
Throughout the four-year installation campaign to date, a number of new technologies were qualified and successfully integrated into the lower completions. These included cableless gauges to provide data closer from the reservoir inflow area, tagged proppant for individual subsea well fingerprinting if proppant is found at the gas plant, and water-tracer technology to aid in identifying the subsea source of potential formation water breakthrough.
This subject explains the extent of the effort to progress an ambitious field development based on big-bore gas wells only (to reduce well count) from the drawing board to flawless execution and world-class production. Relevance also relates to other major big-bore, high-rate gas subsea developments with sand control requirements that are currently being pursued in similar harsh environments (deep water, Arctic conditions, sub-zero seabed) that might have interest in the application of Ormen Lange's successfully implemented technology.
A New technique to Characterize Drilling Fluid Filter Cake
Authors: Elkatatny S. M. , Mahmoud M. A. , Nasr-El-Din H. A. 
Published: June 2011

Abstract
Filter cake characterization is very important in drilling and completion operations. The homogeneity of the filter cake affects the properties of filtration process such as the volume of filtrate, the thickness of filter cake, and the way to remove it. Different models were used to determine the thickness and permeability of the filter cake. These models assume that the filter cake is homogeneous.
The objective of this study is to measure the filter cake thickness and permeability of water-based drilling fluids by a new approach and compare the results with previous models. A HPHT filter press was used to perform the filtration process under static conditions (225°F and 300 psi). CT (computed tomography) scan was used to measure the thickness and porosity of the filter cake. SEM was used to provide the morphology of the filter cake. Leica microscope was used to determine particle size distribution.
The results obtained from the CT scan showed that the filter cake was heterogeneous and contained two layers with different properties. The average thickness of the external layer was 0.1 in., which was greater than the average thickness of the internal layer (0.06 in.). Both the porosity and permeability of the external layer were zero, while the porosity of the internal layer ranged from 10 to 20 vol. %. SEM results showed that the two layers contained large and small particles but there was a very poor sorting in the external layer, which led to zero porosity in this layer. Previous models underestimated the thickness of the filter cake by almost 50%. A new method was developed to predict the thickness and permeability of the two-layer filter cake. This method predicted the experimental data very well.
Computational Fluid Dynamics for Reservoir and Well Fluid Flow Performance Modelling
Authors: Byrne M. , Jimenez M. A. , Rojas E. , Castillo E. 
Published: June 2011

Abstract
Computational Fluid Dynamics (CFD) has been used to model fluid behaviour in reservoirs, near wellbores and wells. More recently the CFD has been applied to more diverse challenges such as sand transport, coupled mechanical modelling of failing wellbores and gas well clean-up. CFD has been applied to model the crushed zone around perforation tunnels and also to predict well performance base on laboratory testing. Where the reservoir is involved in these models they are fully coupled and flow is enabled deep in the reservoir and in to every point along the well.
Capturing the simultaneous flow of fluids in the reservoir and in the well is essential to predict performance in wells and reservoirs with complex geometry. Cross flow between reservoir layers and the flow of fluids through and along the well length are real phenomena which if ignored, can lead to poor prediction of well performance. CFD modelling relies on fundamental physical properties and enables changes in flow restriction such as formation damage or matrix stimulation to be captured. This paper presents some recent case histories where model results are verified by real well performance and where traditional analytical model results are compared to fully coupled CFD reservoir and well models. The impact of formation damage is observed to produce very different results, depending on the model applied.
Case histories illustrating the application of innovative, rigorous modelling of formation damage from different drilling and completion fluids and practices are presented. Further advances that enable sand failure and sand transport to be modelled are also illustrated. The case is made for use of CFD or similar modelling processes where complex reservoirs or complex wells are considered.
New Approach for Completion Applications With Higher Internal Phase Inverts Utilizing Innovative Surfactants
Authors: Luyster Mark , Patel Arvind , Ravitz Ray , Lim Kim S. 
Published: June 2011

Abstract
A new surfactant capable of providing stable emulsions to as low as a 20/80 oil/water ratio while still maintaining a continuous oil phase is now possible. The new surfactant works in a variety of brines allowing flexibility in formulations and applications. The high internal phase emulsion allows formulations of higher density with less total solids. These high internal phase emulsions are stable at high temperatures and provide manageable (adequate) low-end rheological properties suitable for drilling and completion applications. This system demonstrates relatively less syneresis than a conventional invert. Using a higher internal phase requires less oil and subsequently lowers costs both from initial base fluid cost and final disposal of the base fluid. This new surfactant can also be used to formulate systems for conventional alpha-beta gravel packing, whereby the rheology profile approaches Newtonian properties.
This paper will detail the chemistry behind the new surfactant, initial laboratory assessments and the potential applications for this new technology.
Specially Formulated Delayed-Breaker System for Extended-Reach Injectors in a Viscous Oil Waterflood Application
Authors: Kim L. S. , Ravitz R. , Patel A. , Martens H. , Luyster M. , Kuck M. 
Published: June 2011

Abstract
Two wells have been designed and completed using a combination of monitoring, isolation and injection control equipment to provide an understanding of injection behavior in extended-reach laterals and possible matrix bypass events (MBE) in the Nikaitchug field in Northern Alaska. These lower completion designs also provided a means to evenly distribute injection along the length of the lateral section as well as a means of mitigation and control of water if necessary.
In order to facilitate direct injection, a specifically formulated breaker system was developed to provide a delay to allow spotting in the openhole horizontal prior to running the liner and lower completion injection control assemblies. The ability to place the breaker system after drilling the horizontal mitigated risk associated with temporary flowback when inflow control devices were installed. Both post intervention and flow back were not desired.
The breaker system was formulated to provide a delay and allow the liner and injection control assembly to be installed before degradation of the residual filtercake caused uncontrollable losses thus allowing the completion phase to proceed as planned. The filtercake was deposited by a reversible invert reservoir drill-in fluid system used to drill the horizontal sections. The breaker system was unique in that it was blended as an invert emulsion and consisting of an oil continuous phase and an aqueous discontinuous phase that included a glycol acid precursor. An oil-based system was desired to reduce friction thus facilitating the installation of the lower completion hardware for these extended-reach wells.
This paper discusses the upfront assessment process, the reversible invert drill-in fluid system, the chemistry and subsequent optimization of the breaker system to achieve the drilling and completion objectives. In addition, the actual field results and lessons learned will be discussed.
Stimulation Solutions for the High-Pressure, High-Temperature Naturally Fractured Carbonate Reservoirs in Mexico
Authors: Flores Jose G. , de Antunano Munoz Yuri , Diaz Vazquez Alan , Cruz Espinoza Leonardo 
Published: June 2011

Abstract
One of the components in PEMEX's strategy to offset the natural decline of some of Mexico's giant fields consists in the implementation of technological advances and best practices for mature fields. About 70% of the hydrocarbon produced in Mexico originates in naturally fractured, depleted carbonate reservoirs, with active aquifers and secondary gas caps, which makes it difficult to maintain production levels and increase recovery factors. To optimize the reservoir-well-facilities systems, in 2006 PEMEX established, in cooperation with service companies, multidisciplinary productivity teams to generate portfolios of opportunities in all its production assets nationwide. The selection and optimization of stimulation and matrix-acidizing treatments were identified as critical enablers for production enhancement.
The stimulation designs have evolved in several directions, including the utilization of energized fluids, the introduction of emulsified acids, and the application of high-dissolution systems for high-temperature wells. Fluid placement techniques for selective stimulation have improved with the assistance of high-hydraulic-impact tools, inflatable packers, downhole real-time monitoring, and chemical-mechanical self-diverting fluids with degradable fibers to treat high-temperature formations. These improvements and evolutions have brought about solutions to historical problems and made it possible to optimize stimulation treatments in complex carbonate reservoirs with superior production results, including: 1) identifying natural-fracture patterns in low-productivity areas to increase the well-formation contact by acid fracturing; 2) treating and optimizing wells with severe gas breakthrough with strong diversion mechanisms to temporarily isolate the gas channels and stimulate the producing zones; 3) employing selective diversion fluids and non-reactive systems to break emulsions and water blockages in wells with high water cuts; and 4) applying state-of-the art fluids to maximize productivity from new discoveries.
The application of PEMEX's Well Productivity strategy is successfully contributing to maintaining Mexico's hydrocarbon production levels. For example, in PEMEX's South Region, it is estimated that 50,000 BOPD is the average incremental production per year obtained by solving a historical scale and organics deposition problem, and that 35,000 BOPD is the average incremental obtained from new wells by successfully removing and bypassing the drilling-induced damage. This paper discusses the production enhancement workflows, milestones, examples, results, lessons learned and strategies established to meet the production targets in various naturally fractured carbonate fields in Mexico.