bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decreasing Water Invasion into Atoka Shale Using Non-modified Silica Nanoparticles
Authors: Cai Jihua , Chenevert Martin E. , Sharma Mukul M. , Friedheim Jim 
Published: October 2011

Abstract
Fluid penetration from water-based muds into shale formations results in swelling and subsequent wellbore instability. Particles in conventional drilling fluids are too large to seal the nano-sized pore throats of shales and to build an effective mud cake on shale surface and reduce fluid invasion. This paper presents laboratory data showing the positive impact of adding commercially available, inexpensive, non-modified silica nanoparticles (particle sizes vary from 5 nm to 22 nm) to water-based drilling muds and their effect on water invasion into shale.
Six brands of commercial and non-modified nanoparticles (NP) were tested and screened by running a three-step pressure penetration test (brine - base mud - NP mud). Two types of common water-based muds (a bentonite mud and a low solids mud, or LSM) in contact with Atoka shale were studied with and without the addition of 10 wt% nanoparticles. We found that a large reduction in shale permeability was observed when using the muds to which the non-modified NPs had been added. For the bentonite muds, the permeability of Atoka shale decreased from 57.7% to 99.3% and for the low solid muds, the permeability of Atoka shale decreased from 45.67% to 87.63%. Higher plastic viscosity (PV), lower yield point (YP) and fluid loss (FL) of the NP muds compared with base muds were also observed by the addition of NPs. We also found that nanoparticles with size varying from 7 nm to 15 nm are more effective plugging agents than larger nanoparticles for the Atoka shale.
This study shows for the first time that it is possible to formulate water based muds using inexpensive non-modified and commercially available silica nanoparticles and that these muds significantly reduce the invasion of water into the shale. The addition of silica nanoparticles to water based muds may offer a powerful and economical solution when dealing with wellbore stability problems in troublesome shale formations.
Capacitance Resistive Model Application to Optimize Waterflood in a West Texas Field
Authors: Nguyen Anh P. , Lasdon Leon S. , Lake Larry W. , Edgar Thomas F. 
Published: October 2011

Abstract
This paper describes the application of capacitance resistive modeling (CRM) to 99 wells in a waterflooded field in the Permian Basin of West Texas. CRM is a quantitative technique based on material balance that requires only injection, production rates and well coordinates to identify and quantify interwell connectivity in a waterflood. The study uses CRM results to optimize oil production by reallocating water injection and then assesses the resulting improvement by analyzing field data after water injection has been rescheduled. This first field implementation of CRM theory shows that the oil production rate has increased 45 bbl/day and the cumulative incremental oil production in the first year is 5, 372 bbls, equivalent to $402, 900 at $75/bbl.
This work serves as a demonstration of how to apply and analyze CRM results. Before optimizing injection, interwell connectivities were established by fitting CRM over an appropriate fitting window selected using field events. The forecasting ability of the model was examined by fitting part of the historical data and then using the fitted model to forecast the remainder of the historical data. CRM interwell connectivities were used to optimize future production for the next five years by changing water injection rates. The optimized injection rates were applied for one year and the resulting production rates were analyzed.
The oil production rates increase after injection rates were rescheduled according to the CRM optimization. This first field test of CRM technology has demonstrated that CRM has the advantages of short computation time and of using readily available field data, and disadvantages of sensitivity to reservoir events and data errors. The connectivities are consistent with field geological knowledge. CRM can be used to improve oil production with little additional cost.
The case study shows that CRM is a simple yet powerful tool for engineers in planning and monitoring waterflood. The work increases confidence in the technique by demonstrating improvements made by using CRM in a practical context, and identifying shortcomings of the technique. CRM should be applied with knowledge of the field geology and history to understand the results and use them to enhance waterflood performance.
Nonlinear Formulation Based on EoS-free Method for Compositional Flow Simulation
Authors: Zaydullin R. , Voskov D. V. , Tchelepi H. A. 
Published: October 2011

Abstract
Compositional simulation is necessary for the modeling of complex EOR processes. For accurate simulation of compositional processes, we need to couple solution of nonlinear conservation laws for multicomponent multiphase flow and transport, with a system of equations describing the phase behavior of the mixture at q thermodynamic equilibrium. The complexity of the problem requires extensive computations and consumes significant CPU time. We present an efficient and robust framework for the computation of the thermodynamic phase behavior associated with multi-component multiphase flow in porous media. The method is based on adaptive interpolation of supporting tie-lines in compositional space. For the parameterization of full solution of a complex compositional problem we need only a limited number of supporting tie-lines in compositional space. We use a special approach for the adaptive construction of these tie-lines, depending on predefined precision. The parameterized tie-lines are triangulated using Delaunay tessellation, and natural-neighbor interpolation technique is used inside the supporting simplex. The computation of phase behavior for the composition simulation then becomes an iteration-free procedure and does not require any EoS computations. Based on this method, we developed a new nonlinear formulation for fully-implicit compositional simulation for both immiscible and miscible displacement. The treatment of nonlinearities, associated with complex thermodynamic behavior of the fluid, is based on the new set of unknowns - tie-line parameters, which allows for efficient representation of the subcritical region. For the supercritical region we use the standard compositional set of variables that based on the overall composition. A new criterion is proposed for the identification of changes between sub- and super-critical regions, and the robust variable substitution is applied during the simulation process. The efficiency and accuracy of the method is demonstrated for several multi-dimensional compositional problems of practical interest. For the tested problems, the proposed method significantly reduces the computational cost of the thermodynamic calculation compared with the standard EoS-based approach. Moreover, the method shows substantially better nonlinear convergence in the case of near-miscible gas injection simulation.
Inflow Performance Identification and Zonal Rate Allocation from Commingled Production Tests in Intelligent Wells—Offshore West Africa
Authors: Saputelli Luigi , Oluwole Omole , Lissanon Janvier , Gonzalez Fabio , Chacon Alejandro , Sun Kai 
Published: October 2011

Abstract
The main objective of a production well test is to assist in the identification of reservoir and well parameters needed for regulatory accounting, well surveillance, and asset management purposes. Interpreted information is used to drive decisions on production enhancement, operations optimization, and field-development plans. However, uncertain results may occur when wells are produced from multiple reservoirs. Currently, the industry approach is to allocate well and reservoir parameters based on known petrophysical data, offset well information, and zonal well tests. When possible, testing by difference is commonly performed to control one or more zones; however, this process may result in significant production losses with poor concluding results, especially when zonal interference is vital to a well's operating point (e.g., intelligent wells in a waterflood field).
A methodology was developed to consistently identify reservoir and well-performance parameters from wells produced under commingle conditions from multiple reservoir zones by leveraging available real-time data. This methodology was successfully applied in a field located in offshore West Africa, a waterflooded field with nine intelligent wells. The methodology integrates surface well-test rates, pressures, and downhole triple-gauge data. Collected data is validated via a rigorous history calibration process of an integrated production model consisting of an analytical reservoir, well, downhole and surface chokes, and pipeline models. The calculated parameters (e.g., zonal rates, productivity index, reservoir pressure, gasoil ratio, and water cut) are the result of an error minimization between calculated variables and measured field data.
This paper presents applications of this methodology for two production tests of a single dry-tree well with individually controlled reservoir zones. Benefits of the above application include a 90% reduction of the time required to perform a similar analysis, reduced uncertainty in rate allocation and reservoir parameters, and better understanding of the likely production from every reservoir zone. Because well and reservoir parameters are allocated to individual layers, the resulting rate allocation satisfies all sensor data and physical models, and therefore the uncertainty of the allocation is reduced. In addition, the application provides the basis for rate allocation to multiple zones in real time when well tests are not available.
Barite Sag Occurrence and Resolution during Angolan Completion Operations
Authors: McNerlin B. , Oakey N. 
Published: October 2011

Abstract
Barite sag or solids sag is a phenomenon where by a fluid sheared at low flowrate does not have the viscous properties necessary to keep the solids within it in suspension. The solids can subsequently fall out of suspension, which can lead to an undesireable build-up of solids in the wellbore or density contrasts within the fluid. During drilling activities solids sag can be avoided by increasing flow rates, rotating the drill pipe, and viscosifying the drilling mud. However, during completions operations, none of these mitigating practices may be possible due to limitations of the setting tools or installed equipment deployed into the well. For open hole completions where sand screens are deployed in highly conditioned muds, solids sag has the potential to be a serious issue, and needs to be avoided. Since 2009, there have been at least four incidents of solids sag occurring during completions operations in the Greater Plutonio development in deepwater Angola, at relatively low fluid densities. Each event manifested itself in a different way, and caused different problems during and after installation of the completion equipment.
This paper presents case studies of the solids sag events that occurred during completions operations, and how they either affected installation operations or well productivity. It then describes the work done to eliminate the solids sag, including fluids testing performed to identify it, changes to operational practices, short term modifications to mud rheology, and long term mud solutions.
Preemptive Scale Management: Treating with Scale Inhibitor While Frac Packing a Well
Authors: Marquez M. , Schafer L. , Norman W. D. 
Published: October 2011

Abstract
Fracpacks have become the completion of choice for deepwater wells due to concerns over loss of productivity associated with fines and sand production, limited rig availability and high intervention / sidetracking costs. Many deepwater reservoirs also require seawater injection in order to maintain reservoir pressure and increase the ultimate recovery of hydrocarbon reserves. This practice can significantly increase the potential for scaling, particularly the deposition of barium sulphate (BaSO4) scale in reservoirs with high barium concentrations. Mechanical removal of sulphate scale at the reservoir level and / or from a damaged fracpack is not feasible. Chemical dissolution is not always practical, particularly in cases of high scale buildup. In these circumstances, little can be done to restore loss production except for pulling the completion or sidetracking the well. In either case, the consequences of sulphate scale build-up can be detrimental to the economics of the project, especially for high rate producer wells. For these reasons, preemptive scale management, most often in the form of scale squeezes, is a standard operating practice in high value wells susceptible to scaling. Deployment of a scale inhibitor concurrently with well completion operations is very attractive in that it delays the onset of scaling while providing a means for scale inhibition monitoring from the start of production. This not only provides adequate protection in case of early water breakthrough, but it also provides warning to plan and schedule routine well interventions, efficient utilization of resources (rig availability, workover crews, etc.), and better reservoir management.
The addition of a phosphonate scale inhibitor into the pre-frac acid and overflush brine stages preceeding the frac operation was previously discussed in SPE 127768. As an extension of the previous work, a liquid pentaphosphonate scale inhibitor has been successfully incorporated into a seawater-based, borate-crosslinked frac fluid for fracpack operations in deepwater environments. Many challenges, including complex shear and temperature profiles, as well as potential incompatibilities arising from the interaction between the SI, crosslining agent / buffer package, and seawater were overcome by adjustments made to the crosslinking package, polymer loading, and fluid pH. The rigorous laboratory testing that led to the development of optimized fluid formulations, the assessment of scale inhibitor efficacy and formation damage potential is described herein.
Incorporating Geomechanics into the Decline-Curve Analysis of Naturally Fractured Reservoirs
Authors: Jabbari Hadi , Zeng Zhengwen , Ostadhassan Mehdi 
Published: October 2011

Abstract
This paper presents a new production decline model for naturally fractured reservoirs (NFRs), which takes the geomechanical behavior of the formation into account. Since the pressure transient data can be costly and may not be available for most wells, decline curve analysis that uses readily available well production data would be beneficial. Decline-curve analysis methods, in a variety of forms, have been used in the industry to analyze production data and forecast reserves for many years. However, the impact of geomechanics is not considered in the existing models.
As reservoir pressure decreases due to production, fracture aperture can be influenced by both the matrix elasticity and fracture compressibility. This will result in permeability change in the fracture system. To include the impact of the geomechanical properties, a model is derived to understand how pressure change can affect the fracture permeability and behavior of NFRs. It is important to find out this relation since the fractures would close, or at least diminish, after a long period of producing time.
The original model of dual-porosity developed by Warren and Root is extended to include the effect of geomechanical properties on the behavior of the reservoir. From this, a new approach for the decline curve analysis of fractured formations is developed that relates the production decline trend not only to the Warren and Root's key parameters (ω, λ), but also to the elasticity parameter (ε) which reflects the mechanical behavior of both the rock skeleton and the fractures.
The concept of stress-dependent skin around the wells producing from NFRs is discussed and formulated in this work. The behavior of such NFRs at different flow periods are described, from which we found that the effective-stress change can affect the decline-curves from stress-sensitive fractured formations.
Lightweight Cementing Design Improves Zonal Isolation on Challenging High Temperature Offshore Thailand Wells
Authors: Brandl A. , Acorda E. R. , Doherty D. R. , Rajaneekornkrilas V. 
Published: October 2011

Abstract
A cementing system was developed with advanced performances for wellbore zonal isolation in the Gulf of Thailand. Wells in the area are located in shallow water and characterized as deep and hot, with low fracture gradients, with deviated wellbore trajectories. Fast-paced drilling activities and working within the offshore logistical parameters further challenge cementing operations and slurry designs. The paper will discuss laboratory test results and a case history focusing on the significant benefits of a lightweight cement system developed to achieve zonal isolation of wellbores under the given extreme conditions. A sidetrack of a well in the Gulf of Thailand was cemented with the novel cementing system. Cement bond log evaluations confirmed significantly better results in comparison to the cement system used to cement the initial section. These findings were also attributed to the improved slurry performances of the novel cementing system.
An Improved Model for Wireline Formation Tester Pumpout Time Estimation
Authors: Ali Khan Waqar , Wattenbarger Robert A. , Shah Syed Shabbir , Akram Agha Hassan 
Published: October 2011

Abstract
Wireline formation testers are now in their third generation of development. These tools are used to measure formation pressure andpermeability, and to take fluid samples from the reservoir. Technological developments over the years have resulted in a modular tool that can obtain a clean formation fluid sample with minimal contamination. Sampling time varies from a few minutes to many hours depending upon different parameters i.e. depth of invasion, flow rate, formation permeability, anisotropy, porosity and the viscosity of the involved fluids including mud filtrate and formation fluids.
Total pumpout time required to obtain a clean sample is always of interest to both the operator and service company owing to economics, well stability and other factors. An approach is required that is flexible and that requires few parameters to estimate the pumpout time and the time for first formation fluid slug.
In this study a new polynomial model is developed to better estimate the time to first slug.
The new model was tested for different pumpouts from different wells and history matching was performed to test the accuracy of the model. A number of pumpouts were considered and all of those showed close matches. Software was developed to quickly calculate the total pumpout time at real time. Also in this study the previous model was tested and with the limited available data the new model showed much improved results over the previous model.
Downhole Isolation Packers for Drilling Operations: Field Experiences
Authors: Ferrara P. , Molaschi C. , Oppelt J. , Buda R. , Amicosante M. , Grimmer H. 
Published: October 2011

Abstract
In recent years, with the availability of high-performance automated drilling systems, the drilling challenge has moved to even further critical operations involving deepwater and ultra-deepwater environments, HPHT applications, anomalous pressure regimes and reduced margins between pore and fracture gradients. Even though prevention comes first, achieved through best practices and master operating attitude, the availability of tools and procedures to cope with critical events is very important. Nowadays, whenever necessary, a best oil industry practice is represented by Managed Pressure Drilling Systems. These systems consist in a set of surface tools and equipment that enhance drilling capacity and grant a safe drilling process. In case of emergency, the reaction is usually fully devoted to these systems and the blowout preventer (BOP).
For many years, the possibility of introducing both static and dynamic safety barriers directly into the well has been considered to limit the intensity of kick events and achieve a consistent increase of safety. This paper describes two field experiences (in the US and Italy) achieved with downhole isolation packer subs that can be integrated in the drillstring to operate in an open hole as well as above the last casing shoe. Risk-assessment advantages obtained with this technology are also analyzed and reported.
As dynamic barriers, downhole isolation packers complement conventional BOP systems and work in combination with them, to: stop a kick close to the bit, improve well integrity and optimize well control procedures. In case of a kick, while closing the surface BOP is according to standard practices, a downhole isolation packer, as part of the drillstring, can be activated by means of a downlink. The well annulus will be shut in, trapping the kick below the tool, thus enabling it to condition the mud above it and to bullhead the kick back into the formation.
A New Way to Waste Recording, Waste Tracking, and Waste Reporting to Improve Waste Management
Authors: Rusjanto J. , Hartoyo O. , Qory F. , Aripin A. , Saroso R. , Rohman K. 
Published: October 2011

Abstract
Waste management shall be done comprehensively, starts from waste generator to final disposal. Waste management should base on Reduce, Reuse, Recycle, Recovery, and Disposal (4R+1D) principles. A good waste data management will enable us to promote waste management improvement based on these principles. Waste management data consist of waste recording, waste tracking, and waste reporting.
In Total E&P Indonesie, every waste that generate by every entity in each production sites and drilling rigs will be recorded in waste register/Log book. Waste from every site will be transferred to final disposal (senipah) via transit area (handil). Every waste that transfers will be recorded and attached with Waste Transfer Note (WTN) form. Both of this recording system is a paper based systems and has several disadvantages. First, when compiling the waste data from waste register and waste transfer note, there is discrepancy of waste quantity between both of record systems. Second, it needs a lot of man hour to compile the waste data from both recording systems and human error is most likely happen here because of manually recapitulation of waste data which will directly affect the waste data that submitted to authority. Third, it is very hard to track the waste position when transferred, whether it has already arrived in transit area or final disposal because the control paper (Green parts of waste transfer note (WTN) form) often does not come back to waste generator.
Total E&P Indonesie developed an application which aim to replace the waste register and waste transfer note and also solving the entire problem that caused by previous systems. This application is an integrated system of waste register, waste tracking, and waste reporting.
This application called WISEMan. It has a lot of benefit. First benefit is waste recording, tracking, and reporting will need a short time which can minimize man hours. Second benefit is waste engineer in Total E&P Indonesie can focus on Improving Waste Management that refer to Reduce, Reuse, Recycle, Recovery, and Disposal (4R+1D) Principles, and third benefit is improving awareness of waste segregation to all personnel in TEPI premises because the WISEMan system makes the employee compulsory to segregate the waste that generate by each entity.