bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the Invasion Profile and its Components Due to Drilling Fluid Mudcake Filtration, Using the Synchrotron Light X-Ray Fluorescence
Authors: Neto J. C. Q. , Ribeiro J. L. B. , Lopes R. T. , Anjos M. J. , Bianco L. C. B. , Coelho M. V. 
Published: December 2007

Abstract
During well drilling operations, the invasion of the porous media around the wellbore by a certain quantity of drilling fluid components is likely to happen to build a stable mudcake. For a horizontal open hole well, the mud cake is kept during drilling and completion operations giving stability to the borehole. Because the drilling fluid is heavier than the formation fluids, solid particles and fluid components are pushed into the formation establishing a filtration process. At some point, the mud cake must be removed and a clean up procedure is done. For production wells, the majority of the mud cake and invaded components are removed with the well production and the resulting skins are usually acceptable without any secondary treatment. However, for injection wells, such removal is always a problem and special treatments are needed. The success of such treatments is based on the knowledge of the invasion profile and their composition. Therefore, a better characterization of the invasion profile could improve substantially the clean up procedures and the treatment selection.
In this first result the aim of study is to address this problem an experimental procedure was developed to identify and characterize the profile of drilling fluid invasion. This technique used the X-Ray Fluorescence Beam line (XRF) from the Synchrotron Light at the Brazilian Synchrotron Light National Laboratory (LNLS) in Campinas, São Paulo State, Brazil figure 1. This methodology allowed the determination of the invasion profile in synthetic unconsolidated sandstones similar in composition to the reservoir rocks.
Along with the invasion profile, μ-SRXRF analysis was used to map and identify drilling fluid components that may have invaded the core. The identification of these components provided information to differentiate and identify carbonates and polymers in terms of concentration and penetration.
Dynamic Mud-Cake Removal Evaluation Under Annulus Hydrodynamic Conditions
Authors: Robles J. , Criado M. A. , Jensen E. , Morris W. 
Published: December 2007

Abstract
In the last decade drilling fluids have undergone a continuous evolution towards the challenges of new drilling technologies. This process forced cementing companies to improve the mud-cake cleaning systems efficiency in order to achieve successful cementing jobs.
A basic procedure to evaluate drilling fluids compatibility with spacers, preflushes and cement slurries is provided in API recommended practice 10 B. However, no quantitative methods to evaluate preflushes mud removal efficiency are proposed. On the other hand, several laboratory methods have been developed to analyze this issue, although most of them are based on experiments performed at unrealistic down-hole conditions.
This paper presents a new laboratory method to dynamically evaluate preflushes performance. The drilling fluid is circulated through a cell at a similar hydrodynamic flow regime expected in the well annulus. The mud cake is generated on four different filtering materials, applying differential pressure at the bottom hole circulating temperature.
The mud and filter-cake removal is evaluated by two different techniques, static gravimetric and dynamic impedance. This last technique provides a continuous indication of the cake thickness variation during the test. Therefore, the preflushes chemical, viscous and abrasive action can be evaluated while the test is conducted.
Three case studies, a low solids KCl, a PHPA and a plain water base drilling fluid, are reported were the performance of different preflushes systems are evaluated. The results of these studies were used to modify the preflushes pumping sequence and to adjust their volumes based on the information obtained from the impedance trends. The cleaning efficiency of viscous spacers used in-between chemical washes and the effect of mud filter cake leek off are discussed.
Sulfate Removal for Barium Sulfate Scale Mitigation -- Kinetic vs. Thermodynamic Controls in Mildly Oversaturated Conditions
Authors: Simpson C. M. , Graham G. M. , Collins I. R. , McElhiney J. , Davis R. 
Published: December 2007

Abstract
Conventionally, scale mitigation is achieved using chemical inhibitors either by squeeze treatment into the reservoir or continuous injection. However, with new fields encountering increasingly more challenging environments, or when the economic impact of chemical intervention by squeeze treatment is large (e.g. subsea fields with poor bullhead chemical placement), other methods of scale control such as the use of low sulphate sea water (LSSW), must be considered during the front end engineering and design (FEED) stage of a field development. Nevertheless, for conventional sulphate reduction packages (SRP's) that reduce the sulphate concentration in the injected sea water typically towards 40 – 50 ppm, there remains a residual scaling risk and the requirement for periodic squeeze treatments.
Previous work reported at the 2004 SPE Oilfield Scale symposium (SPE 87465) examined the level of sulphate reduction required to mitigate the requirement for even periodic squeeze treatments against barium sulphate scale. This showed that sulphate levels of 20 ppm were required in order to prevent scale formation under down hole production conditions, although it was also demonstrated that thermodynamically the system remained oversaturated with barium sulphate.
This paper expands considerably on this preliminary "field specific" case and examines the impact of LSSW on the scaling kinetics across a broad range of formation water compositions (barium ranging from 150 ppm to 650 ppm) and at temperatures between 80°C and 120°C. The paper therefore investigates the relationship between scaling kinetics and thermodynamics in relatively mild scaling environments and illustrates that whereas extremely low levels of sulphate would be required to completely prevent scale from a thermodynamic viewpoint, the kinetics of scale formation may prevent scale precipitation under down hole production conditions, with additional continuous injection inhibitor applied at wellheads to protect flow lines etc. In summary, this paper presents results from an extensive series of long term dynamic flow and pseudo static performance tests designed to determine the relative impact of thermodynamics and kinetics on the residual barium sulphate scaling risks associated with the injection of LSSW for pressure support.
Wireline Replacement in Pilot Wells by LWD Tools Including Formation Testers
Authors: Tigre C. , Rafainer G. 
Published: December 2007

Abstract
The use of an eight-inch diameter formation-tester-while-drilling tool for 12 ¼ in to 16-in. holes has provided the option to significantly if not totally replace wireline logging operations in pilot sections of planned horizontal wells in Brazil. When using LWD tools only, sections of a pilot interval do not need to be plugged and abandoned, as had been the practice. The option with a complete suite of LWD tools can greatly reduce operational risks and save time and money. Savings of up to six rig days and US$ 900.000,00 can be expected.
In the past, a 12 ¼ in pilot section was drilled before the horizontal section of a planned horizontal well was developed. The purposes of the pilot section were to confirm top and base of target reservoir and evaluate its production characteristics. While drilling pilot sections, the LWD tools were limited to gamma, resistivity and pressure while drilling. Thereafter, a more comprehensive wireline logging suite was run including, wireline-run formation testers. To avoid the need for a costly pipe-conveyed logging runs, these sections were also limited to inclinations less that 50 degrees. After the logging runs, the pilot sections were typically plugged and abandoned with a sidetrack section drilled off the top of the last cement plug.
The availability today of LWD formation tester allows for a new and less costly option. The 12 ¼ in. section of the planned well takes an S-shape profile, getting close to the target reservoir at inclination higher than called for in running wireline, dropping off to reach the base of the reservoir and continuing to its final TD destination. It is not necessary to plug and abandon all the pilot section, and the planned drilling, including logging, can be completed more quickly and efficiently.
Improving Water Saturation Prediction with 4D Seismic
Authors: Wu J. , Mukerji T. , Journel A. G. 
Published: December 2007

Abstract
Seismic data provides a unique source of information widely used for reservoir characterization. High resolution 3D seismic impedance field is critical for building a model of facies distribution. 4D seismic time-lapse can reflect the water saturation difference (time-lapse), hence could point towards potential facies (dis)continuities not originally apparent from the static data.
An interactive procedure is proposed to improve the prior facies model by spotting areas of large discrepancies between the recorded 4D seismic data and the corresponding forward simulated time-lapse data. Various indicators of discrepancy are proposed. The subsequent correction honors the prior geological scenario. It is fast because it does not call for any iterative optimization.
Resolving the Nightmare of Performance Reporting and Portfolio Management - A Web Based Approach
Authors: Nickle B. , Strickland R. , Purvis D. 
Published: December 2007

Abstract
Many papers have been written concerning the energy industry's need to become more efficient in its methodologies and operations. The shrinking qualified workforce and global economic factors are placing further pressures on the energy sector to streamline processes. This requirement extends itself to all phases of the energy industry, especially with multidisciplinary multi-organizational teams.1-5
For the past 5 years a major private equity player has successfully exploited the digital oil field to streamline its asset management processes. This company manages its 2.3 billion dollar oil and gas portfolio with a staff of 5 professionals by utilizing a web-based portfolio management tool. This same staff of 5 annually approves over $100 million in AFE's.
Since inception this web-based application has been successfully deployed to manage 36 different partnerships across the United States. This system has benefited by the proactive input of over 300 industry professionals throughout the application development and deployment cycles. The software currently consists of over 60 different analytical tools to analyze the performance of a portfolio.
This paper examines the use of web based technologies to build a portfolio management system. There are many pitfalls and challenges to overcome to ensure the success of an application designed to monitor performance and measure value. From specifications through rollout to E & P companies aspects of design and deployment are thoroughly explored.
Permeability Estimation Using a Hybrid Genetic Programming and Fuzzy/Neural Inference Approach
Authors: Xie D. , Wilkinson D. , Yu T. 
Published: December 2007

Abstract
We have developed a methodology that provides permeability estimates for all rock-types or lithologies, for a wide range of permeability. This is a hybrid Genetic Programming and Fuzzy/Neural Net inference system and which utilizes lithologic and permeability facies as indicators. This work was motivated by a need to have a volumetric estimate of permeability for reservoir modeling purposes. To this end, for our purposes, the inputs to this process are limited to properties that can be estimated from seismic data. The permeability transform is first estimated at the well locations using core permeability, elastic parameter logs and porosity. The output from the process can then be used, in conjunction with estimates of these properties from 3D seismic data, to provide an estimate of permeability on a volume basis. The inputs are then, the volume of shale (Vsh) or any other log type used to determine lithology, the sonic and density logs, the porosity log and core permeability measurments. The transform system is composed of three distinct modules. The first module serves to classify lithology and separates the reservoir interval into user-defined lithology types. The second module, based on Genetic Programming, is designed to predict permeability facies within lithology type. A permeability facies is defined as as a low, medium or high permeability set associated with each lithology type. A Fuzzy/Neural Net inference algorithm makes up the third module of the system, in which a TSK fuzzy logic relationship is formed, for each permeability facies and lithology.
The system has been applied in two oil fields, both offshore West Africa. In comparison with current estimation approaches, this system yields more consistent estimated permeability. The results from conducting cross-validation suggest this methodology is robust in estimating permeability in complex heterogeneous reservoirs. This system is designed to use elastic log properties inverted from seismic data, such as acoustic velocity and density as input so permeability volume can be obtained.
Nonpolymer Surfactant Enhances High-Strength Hydrofluoric Acid Treatments
Authors: Cawiezel K. E. , Devine C. S. 
Published: December 2007

Abstract
Traditionally, operators have been reluctant to use acids with HF concentrations greater than 3% to remove drilling mud and stimulate the near wellbore region due to fear of formation deconsolidation in the near wellbore region. With some formations, even 3% HF concentrations will cause deconsolidation.
During recent laboratory testing, it was discovered that the addition of the surfactant ("TH-1") to several conventional mud acid formulations and to several strengths of Retarded Acid System (RAS) formulations produced good stimulation in sandstone formations.
Results of testing indicate that the use of the surfactant produces acid formulations which exhibit improved penetration of live acid, increase post-test permeability of test samples by a significant amount, and minimize rock disaggregation at the core face.
The concentration of surfactant added is dependent on the unstimulated permeability of the rock, the rock mineralogy, and the temperature of the test. The concentration of surfactant tested to date ranges from 0.25 to 2%.
Acid containing the surfactant may plug off higher permeability zones and streaks in test samples, allowing the acid to react with lower permeability streaks and zones.
This technique is useful for self-diversion of acid treatments in sandstones and for causing a significant increase in permeability in sandstones which cannot be fracture stimulated. Hydrocarbons contacting the fluid during flowback will break the stiffened acid. The system is polymer-free so no polymer damage is present.
Optimization of Synthetic-Based and Oil-Based Mud Displacements with an Emulsion-Based Displacement Spacer System
Authors: Berry S. L. 
Published: December 2007

Proposal
Effective removal of drilling muds and related solids from cased wellbores prior to adding solids-free brine during the completion process is a critical point for well operations. Efficient displacement of the drilling fluid itself and any particles attached to the casing wall is essential to maintain completion brine and mud integrity, as well as to reduce filtration costs and rig time. A failed displacement can lead to completion complications (such as stuck packers) or potential formation damage due to loss of drilling mud solids to the formation. Modern drilling fluids have progressed to meet more challenging, drilling applications, as well as stricter health, safety, and environmental standards. Many of these advanced drilling fluid systems contain new emulsifier and additive packages, which have increased the difficulty in removing drilling mud from the cased wellbore with traditional displacement spacer surfactant systems.
This paper discusses a laboratory test used in the mud removal studies with an emulsion-based displacement spacer. It also details the efficiency of an emulsion-based displacement spacer in removing actual field compositions of synthetic (SB) and oil-based (OB) drilling muds. Mud parameters such as density, base-oil type and rheologies are detailed to characterize the type of mud and the difficulty in displacing the mud system from the wellbore casing. Also, the environmental advantages of this low-toxicity, non-polluting emulsion-based displacement system are outlined.
Field case histories detail the use of this emulsion-based spacer in the North Sea to displace a wide range of SB/OB drilling mud systems. This paper also outlines how this product optimized removal of SB/OB drilling mud systems, decreased rig operation time, and reduced the volume of mud solid slop due to efficient phase separation and emulsion breaking of the drilling mud systems.
A Novel Response Surface Methodology Based on "Amplitude Factor" Analysis for Modeling Nonlinear Responses Caused by Both Reservoir and Controllable Factors
Authors: Li B. , Friedmann F. 
Published: December 2007

Abstract
Response surfaces (RS) are proxies to reservoir simulators. They relate responses, such as oil rate to key reservoir (i.e., geological parameters) and/or controllable (i.e., wells parameters) factors in simple analytical forms. These proxies can then be used for uncertainty computation, instead of time consuming simulators.
Validity and Efficiency of RS construction techniques depend on the degree of non-linearity. Traditional design of experiments (DOE) coupled with regression methods generate polynomial-type RS. They work well for mildly non-linear problems. However, the reconstructed RS can become substantially inaccurate, if RS exhibits stiff non-linear features. Substituting interpolation methods for regression often improves a proxy's accuracy. However, they tend to smooth out non-linearity and are costly when the non-linearity is unevenly distributed in the parameters' space. Efficient experimental space partitioning coupled with interpolation can further improve proxies' accuracy1. However, space partitioning results in low computation efficiency.
We introduce a novel response surface methodology (RSM), which accurately and efficiently handles non-linear effects without space partitioning. The basic idea is to model non-linear responses by: Identifying a kernel sub-space of the initial parameters space which contains the factors causing highly nonlinear effects on RS;Extracting the highly non-linear effects from RS by ‘amplitude factor’ analysis;Treating all other effects by ‘phase factor’ analysis;Modeling all effects on the response with ‘thin plate’ spline interpolants.
We then test this method to generate RS of arbitrary shapes using a synthetic model and a real reservoir model. We generate RS for oil rate and water cut as functions of key parameters. We validate this method's accuracy for the reconstructed RS and the data collection efficiency. We also compare it with traditional RSM. We show that this novel methodology outperforms other standard RSM when nonlinear effects on RS are very strong in the parameter space.
Managing Drilling Performance: Technical Analysis, Well Challenges, and Field Engagement
Authors: Iyoho W. , Adeleye A. , Virginillo B , Hovland K 
Published: December 2007

Abstract
Within a climate of increasing oil and gas prices, drilling has been caught in a cycle of new, more expensive technology and increasing service and commodity prices. In order to maintain cost effective drilling excellence, Anadarko Canada Corporation's drilling department has developed a multifaceted approach with three major components; pre and postdrill analysis, collaboration and technology. While these three components are commonly part of any current drilling operation, the rigorous approach ACC has applied continues to generate uncommon results in both in-fill and more technically challenging, poorly delineated drilling fields in Western Canada.
Our approach and the results generated in two distinct areas of operation are outlined here.
Getting Full Value from Reserves Audits
Authors: Etherington J. R. 
Published: December 2007

Abstract
Most oil and gas companies retain consulting firms to conduct "independent audits" of a portion of their annual reserves disclosures. Processes are loosely based on financial audits, but there can be significant differences.
Reserves are estimated marketable quantities and values of oil and gas resulting from a defined development plan. The process that examines the standards, controls and procedures applied to prepare these estimates can take several forms: 1) a "reserves evaluation" is a full independent study using raw data, 2) a "reserves audit" employs sufficient tests of the client's evaluations to provide an opinion that results are free from material misrepresentations, 3) in a "reserves review", the auditor assesses the "plausibility" of results based principally on staff interviews, and 4) a "reserves process audit" critically examines the overall procedures and controls applied by the company.
Regulatory disclosures are usually confined to a subset of the total resource assessments used for internal project planning. For example, the Security and Exchange Commission (SEC) guidelines restrict disclosures to Proved reserves and this may be the only estimate provided by audit firms. It is recommended to specify a full reserves and resource audit using a combination of Society of Petroleum Engineers (SPE) and SEC guidelines. Results can then be used to validate a single assessment that supports both disclosures and internal planning.
Many authors contend that full evaluations by an external consulting firm should form the basis of all reserves disclosures. Critical analysis of alternative reserve assessment work flows challenges this approach. The preferred model places third party evaluations in the context of a total quality assurance and control process managed by an internal but independent, corporate Resource Management group.
The project team responsible for a property's development is best positioned to forecast production (reserves) and cash flow (value) scenarios. However, to protect against internal bias, a second, independent opinion may be sought. Given the major uncertainties involved, it is not unusual to obtain significantly different interpretations. Assessments can be improved by engaging the teams in a discussion of their assumptions and interpretations. This process model gets full value from reserves audits