bluuebunny/crossref_metadata_2025_split huggingface dataset:
Service the Limit—Operational Excellence in Well Intervention
Authors: Anyanti Sylvester C. , Hopmans Paul A. 
Published: December 2007

Abstract
Well Intervention cost makes up a major part of the total operating expenditure in Shell EP Asia. The belief that well service operations are constrained to original well design and little could be done in the area of service optimization has made not a few to miss the opportunity of delivering operational excellence.
Service the Limit (STL) is an offspring of the Drilling the Limit* (DTL) methodology, widely applied by Shell Well Delivery teams. Until recently, this structured approach to value creation and realization existed only in drilling operations. STL is about replicating the DTL practices while servicing completed wells.
The DTL methodology and its application to drilling have previously been described in great detail; the intent of this paper is to highlight the experience of applying this methodology to well intervention planning and execution.
STL was introduced to Shell EP Asia (Malaysia and Brunei) in late 2003, with initial focus on training of champions and optimizing the execution phase of well service operations. This led to over 10% cost reduction. The quick-win encouraged a replication of the methodology in other parts of the region, with added focus on front-end activity loading, alignment to Shell EP Global Well Delivery Process and its integration with other hydrocarbon maturation processes.
It is recognized that irrespective of the versatility of a process, the primary activities, carried out by real people is what makes most of the difference in performance. STL is a systemic tool designed to support the people; it is an improvement to the isolated or once-in-a-while well intervention program optimization reviews. Uptake of this methodology will help the EP organizations to better face challenges ahead, especially in deepwater environments.
This paper will cover implementation of STL methodology, associated activities, results and future sustenance plan.
Optimization Process Extends Application of PDC Bits to Reduce Cost in Major Russian Fields
Authors: Jidkov Alexander , Zalogin Boris , Pritchard Wyatt , Dmitruk Sergei , Byvald Edward , Gaifullin Farid 
Published: December 2007

Abstract
In the harsh drilling environments of Siberia where logistics are difficult and expensive, a process of design optimization has led to successful application of PDC bits in the intermediate hole section of development wells, reducing costs and resulting in a record footage performance of 13944 meters – and counting – by a single 11-5/8" PDC bit.
To control costs in the remote Ust-Vakh area of the Samotlor Field of Siberia, bits and equipment must perform at an optimum level. Typically drilled using roller cone bits and turbine motors, the application requires sufficiently rugged equipment to efficiently drill sand/shale formations without costly and time-consuming trips for repair or replacement.
This paper describes the practical evolution from use of roller cone bits and turbine motors in the intermediate hole section of these wells, to use of fixed cutter PDC bits and positive displacement motors (PDMs). The resulting performance improvements are documented, including a world footage record of 13944 meters. To facilitate rapid deployment of application-specific bit technology despite the remote location, an in-house bit specialist was located at the field operations base, collaborating with the drilling department in implementing the optimization process. Focusing on the intermediate hole section from approximately 430m to 1100m depth, areas of potential improvement were identified, and solutions proposed.
Based on success in similar applications, fixed cutter bits were recommended that incorporated steel body designs with advanced hydraulics, while analysis of various bit/BHA combinations identified the most efficient configurations for this application.
Ultimately, large diameter roller cone bits with an expected life of one or two runs were replaced by steel body PDC bits that have been re-run as many as a 20 times or more, with average days per drilling in intermediate section reduced from five to just four days.
The paper summarizes savings realized, and describes additional design changes now under investigation.
Evaluation of Acid Treatment Results for Water Injection Wells in Saudi Arabia
Authors: Al-Harbi M. S. , Al-Dhafeeri A. M. , Al-Rufaie Y. A. , Mohammed S. K. 
Published: December 2007

Abstract
Several acid treatments were conducted in the Ghawar filed to increase the well injectivity and to support the reservoir pressure in this area. Vertical and horizontal wells with an open hole completion in a carbonate reservoir were selected to be a candidate for post acid treatments evaluation study. These wells were stimulated using hydrochloric and emulsified acid with foamed viscoelastic-based water. Viscoelastic-based water system was used to enhance the diversion mechanism and the lifting process for the spent acid following the treatment.
In this paper new correlations for acid treatment design were obtained from an extensive study of several case histories that can be used for optimizing future acid treatments design in the Ghawar field. This study was mainly utilized the results from the post acid treatment jobs in terms of HCl acid, emulsified acid and viscoelastic volume correlated with the well's injectivity.
Based on the study results, there is a strong relationship between the emulsified acid volumes with the injectivity index for the selected wells.
Effective Well and Reservoir Management Reverses Production Decline in a Major Brownfield in South Oman
Authors: Choudhuri Biswajit , Al-Qarshubi Ibrahim , Sadek Ehab , Bharti Sanjay , Mahrooqi Salim 
Published: December 2007

Abstract
A large brown-field in South Oman showed decline in production despite moderate level of in-fill drilling over the last few years. The field has four major reservoirs distributed across three stratigraphic horizons and contains moderate to highly viscous oil (60 to 400 cp). The reservoirs comprise unconsolidated fluvial, fluvial deltaic and glacial sandstones of Palaeozoic age. The geologically complex field due to large number of faults and fractures has been on production for more than 25 years and has been developed using vertical and horizontal wells during different phases of development. Water-flooding is in operation in two of the major reservoirs for more than 5 years. Well and Reservoir Management in this field poses a formidable challenge due to:
Significant well-stock (more than 450 wells) of different types (vertical, horizontal, multi-lateral) Problem associated with data acquisition as all the wells are completed with pumps (beam pump, progressive cavity pump and electrical submersible pump) and most of them are completed with some sand-control device Water-flood management under very adverse mobility conditions in presence of faults and fractures often resulting in premature breakthrough of injected water Logistical problems associated with large distance between the Well and Reservoir Management team at corporate office and the operational team at field location.
The case study presented in this paper describes how a sustained well and reservoir management strategy implemented across the entire value chain starting from the planning to operation stage in this field could not only arrest but literally reverse the field production decline trend using the existing well stock. The paper clearly illustrates that success of reservoir management rests not only on the application of right technology but more on close integration among various disciplines in a cohesive work environment.
Can the Existing F&G Detection System Provide Safe Guard Against All Possible Gas Releases? (Case Study)
Authors: Shabaka Ashraf E. 
Published: December 2007

Abstract
The Fire and Gas detection systems in many of the existing facilities were designed in a conventional method without software modeled design and therefore their performance are questionable. This is due to the fact that at the time when designed, the dispersion and fire were not yet widely implemented.
Since the major accidents are unlikely to occur and it is therefore uncommon to revisit and verify the adequacy of the design of these systems.
This paper discusses the importance of revisiting the design of the existing fire and gas detection systems and its rule in saving our facilities from major losses.
Clustering and Corridoring Project
Authors: Elabed Amjad , Remisio Luis , Katchi Khaliquzzaman , Rahim Ihtisham Ur 
Published: December 2007

Abstract
By late 90's, Abu Dhabi Company for Onshore Oil Operations (ADCO) started facing increasing surface congestion and related potential operating hazards caused by haphazard laying of new surface assets/facilities in ADCO concession areas due to the implementation of aggressive field development plans. ADCO Management realized very early the need to reduce congestion and reduce the risk to the equipment and personnel while coping with the increased number of surface equipment as business needs expanded. As a result, the Clustering and Corridoring (C&C) Project was launched in 2003 and was divided into three studies phases. Phase I and II studies defined the optimum configuration of the facilities to control congestion and reduce the surface facilities footprint. The studies outcome was the development of four main design concepts:
Exclusion Zones, Well Pairing, Corridors Design, and Radial Corridors Layout.
Phase III studies resulted in the re-defining of Production Pad concept in order to meet the long term field development requirements. To date a total of 81 flowlines have been laid in the corridors in all ADCOs' major fields and a total of 24 wells were clustered since May 2005 in line with the Clustering and Corridoring Project guidelines.
Applications of Acoustic Liquid Level Measurements in Gas Wells
Authors: McCoy J. N. , Rowlan O. L. , Becker D. , Podio A. L. 
Published: December 2007

Abstract
Optimum production of gas wells requires static and flowing pressure surveys to detect excessive liquid loading. Wireline pressure surveys have been customary in spite of their cost and potential safety risks. Developments in digital acoustic fluid level technology have resulted in being able to undertake, not only static bottom hole pressure calculations from fluid level measurements, but also to extend this technology to flowing pressure surveys in gas wells. The new procedure involves monitoring fluid level and pressure in the tubing during a short-term test sequence. The procedure is inexpensive and non-intrusive. Tests clearly show the redistribution of flowing gas and liquid and allow the construction of the corresponding tubing pressure traverse and the determination of the flowing gas/liquid ratio, liquid fallback volume and flowing BHP. Examples of tests performed in operating gas wells that are flowing above or below critical flow rates are discussed in detail.
Integrated Interpretation of Production Data and Reservoir Fracturing Treatment Data Aimed to Improve Performance of Well Stimulation Operations by the Example of Vasyuganskaya Formation
Authors: Beryuschev S. , Bebee R. , Shaoul J. , Davidson B. , Vasiljeva V. 
Published: December 2007

Abstract
Hydraulic fracturing (HF) became one of the main techniques for production enhancement in the Pokamasovskoye oilfield.
While analysing production data (Qliq, water cut, BHP) and fracturing data (net pressure), similar trends became apparent, relating to the proportion of oil and water production after fracture treatments. In particular, after analysing several wells we were able to find similar explanations for production profiles before and after treatments.
Correctly determining initial conditions was the basis for developing this integrated approach. In particular, the following parameters: formation pressure (including measurements from observation wells); long term pre-fracture production data; permeability calculated with petrophysical relationship "core-SP"; identifying lithology types from openhole & cased hole logging data for sandstone, shaly-sandstone, shale, tight rock; rock-mechanics properties measured on cores (E, v); fluid rheology (k', n', viscosity); water source (pH, Fe, Cl); and "StimLab" proppant specifications (including proppant damage factor for reservoir conditions).
P-Wave Azimuthal AVO in a Carbonate Reservoir: An Integrated Seismic Anisotropy Study
Authors: Johns M. K. , Wang D. Y. , Lu C. P. , Sun S. Z. , Xu S. , Zhou Da 
Published: December 2007

Abstract
Seismic anisotropy is sensitive to intensity and orientation of fractures aligned by tectonic or local stress field. Azimuthal anisotropy of amplitude versus offset (AzAVO) is one common measure of seismic anisotropy for fracture detection. For this study, we calculated P-wave AzAVO attributes for a lower Cretaceous limestone reservoir in east Texas. Our study tests AzAVO inversion for the relatively low-fold, fair data quality typical of some land surveys. We developed a workflow to integrate the AzAVO inversion with rock physics, forward seismic modeling, seismic-scale fault interpretation, image logs, and core.
Our AzAVO inversion method was based on Rüger's equation, which describes the observed reflectivity (R) as a function of normal incidence amplitude (A0), AVO slope (B0), anisotropy magnitude (B1), anisotropy orientation (ϕ0), and noise (ni):
R ( θ i   ,     ϕ i ) ∼ A 0 + [ B 0 + B 1 cos 2 ( ϕ i − ϕ 0 ) ] sin 2 θ i + n i
Inversion of Rüger's equation yielded four attribute volumes (corresponding to A0, B0, B1, and ϕ0). Additionally, we proposed a additional data quality parameter which describes the relative amount of the total reflection energy predicted by the model. Pre-inversion processing carefully preserved signal via random noise attenuation, super-binning, bandwidth balancing, and phase alignment.
In general, AzAVO inversion displayed geologically interpretable, high anisotropy anomalies. Noise, however, limited our confidence for quantitative fracture prediction. On the flanks of the anticline, data quality was high (greater than 50% fit). Here the magnitude of the anisotropy (B1) volume showed strong lineations parallel to NE-SW trending faults. Over the crest of the anticline, the inversion quality was degraded by an overburden effect, coincident with poor data quality fit (less than 50%). AzAVO orientation maps were noisy and in some places obscured by an acquisition footprint. Locally, however, AzAVO orientations were parallel to ENE fracture orientations from core, maximum horizontal stress from image logs, and fast-velocity direction from a dipole sonic log.
Application of Model-Based Uncertainty Analysis
Authors: Lee Li-Bong W. , Krum Glenn L. , Yao Tingting , Wattenbarger Robert C. , Landis Lester H. 
Published: December 2007

Abstract
Model-Based Uncertainty Analysis (MBUA) is a method to evaluate reservoir performance using multiple 3D models. Experimental Design techniques are used to determine which 3D models are built (unique geologic models which are then simulated) based on the number of identified uncertain factors. This method determines main factor effects and factor interaction effects and results in a multivariable response surface for each desired outcome (i.e., EUR, STOOIP) that can be used for Monte Carlo simulations. The entire MBUA process results in tornado plots, exceedence curves and a method to build representative models.
A key strength of the MBUA process is the ability to quantify the uncertainty of dynamic responses such as water rate, production at early times and plateau length. These responses provide project teams a greater understanding of how their subsurface uncertainties impact field performance and can help guide additional technical work, development planning decisions and representative model building.
We have applied either a full or partial MBUA process to several fields for the purpose of identifying key technical uncertainties and improving the development plan across likely outcomes. Once an initial base case model has been constructed, the Reservoir Evaluation Time Reduction (RETR) work process is used to rapidly and efficiently build subsequent geologic and flow simulation models (totaling 16-54 models). Production data have been incorporated through either history-matching the initial base case or examining Monte Carlo simulation results for potential trends.
The uncertainty analysis provides a streamlined process to examine potential uncertainty factors and allows a project to make informed decisions regarding future technical work or potential mitigation plans.
Petrophysical Evaluation of the Igneous Gas-Bearing Reservoir Fractured—A Case Study at Xujiaweizi Area Outside Daqing Oilfield, China
Authors: Huang Wei , Zhang Yujin , Hu Yingjie , Liu Chuanping , Yin Changhai , Bian Yingshi , Zhang Fugong , Kong LIngfu , Li Tiejun 
Published: December 2007

Abstract
The igneous formation fractured; located at the YC1 and YC3 stratigraphic intervals at Xujiaweizi area outside Daqing oil field, China, had preliminarily shown a huge potential gas resource. That formation is the major gas exploration & development target in future, and a main provider for the gas reserve estimate and gas production. The igneous's low porosity made the resisitivity readings consistently high and detailed information about the formation productivity was difficult to obtain. As the results, the parameters, which used to estimate the gas reserves, were not completely determined by using of the conventional petrophysical methods on the openhole logging data. In order to provide the accurately gas reverse estimate and reservoir characterization in this area, the detailed petrophysical evaluation must be carried out based on the wireline log, core, gas chromatograph, well testing and producing data. This paper presents the case study on the petrophysical evaluation of the igneous gas-bearing reservoir fractured based on the data from 15 wells in which 3 wells were cored and 11 intervals in 4 wells were tested. The major contents are as follows, geological and logging features of the igneous formation, lithology identification of the igneous formation, determination and study of the petrophysical parameter (reservoir height models), identification of gas reservoir and determination of net pay and reserve parameter.
New Design Models and Materials Provide Engineered Solutions to Lost Circulation
Authors: Whitfill Donald L. , Jamison Dale E. , Wang Max , Thaemlitz Carl 
Published: December 2007

Abstract
The prevention and remediation of lost circulation during well construction employs engineered solutions that require a menu of services and tools to support the planning and application stages. Specialty software is used during the planning stage leading to the application of unique products and systems during the delivery stage. A feasibility study by technology specialists may include a wide range of tools during the planning stage to support data acquisition, modeling and design of the application stage. Planning services include hydraulics and fracture characterization modeling to assess expected Equivalent Circulating Densities (ECD) and their effect on potential lost circulation intervals. The fracture characterization modeling for borehole stress treatments uses a module that calculates both the expected fracture width and the particle size distribution required to plug the induced fracture and prevent propagation. The effect of these additions on the rheology of a non-aqueous drilling fluid can then be determined by the use of a new predictive rheology model. Application services may include real-time data acquisition to support delivery of specialized lost circulation materials and systems in either a preventive (pretreatment and/or borehole stress treatments to strengthen the wellbore) or corrective mode (mitigating lost circulation and, where possible, providing additional wellbore strength).
Well-Collision Risk in Congested Environments
Authors: Poedjono B. , Akinniranye G. , Conran G. , Spidle K. , San Antonio T. 
Published: December 2007

Abstract
Well-collision avoidance has gained greater importance as fields become more crowded and well paths increasingly complex. The safety and financial implications of shutting in production wells on platforms or repairing damaged wells have established a need for the industry to evaluate the potential for collision with a producing well.
This paper will cover three main topics related to minimizing the risk of well collisions:
Evaluating the risk Managing the risk Demonstrating the results of the new risk-minimization process
The paper will detail the processes of gathering appropriate data such as completion type, offset surveys, well pressures, casing depths, reservoir fluids and mud densities. Each well and field poses different challenges; not all data is available and wells can vary from simple vertical land wells to crowded offshore and fishbone multilateral designs.
The well position uncertainties are determined by using survey error models from the Industry Steering Committee on Wellbore Survey Accuracy. This method was chosen because it is an industry-recognized standard of defining the magnitude of survey uncertainty.
Recommendations for minimizing risk are based on the status and conditions of the adjacent wells and the nature and severity of the risks associated with a collision. These recommendations are formulated to minimize the risk while ensuring that production is disturbed as little as possible.
Production Tubing String Design for Optimum Gas Recovery
Authors: Poe B. D. 
Published: December 2007

Abstract
This paper presents the results of an investigation of the design of production tubing string setting depths in gas wells to optimize gas recovery in wells that produce free liquids in conjunction with the gas. Particularly important in this work has been the evaluation of the conditions for which the well outflow velocity is less than that which would be required to continuously transport and unload liquids from the well. Sub-critical velocities are often encountered in low productivity gas wells that produce liquids, whether the wellbore liquids are produced directly from the formation and/or condensed from the gas in the wellbore. The produced liquids considered in the analysis can be water and/or liquid hydrocarbons.
This paper presents an optimization technique for determining the most efficient production tubing string setting depth design that will keep the wellbore continuously unloaded of produced liquids, yet result in the maximum gas recovery possible under those conditions. The optimization can be performed for a single completion operation during the productive life of the well, or for a series of periodic well interventions during the productive life of the well for which the tubing string setting depths are selected.
The wellbore liquid-loading mechanism in a sub-critical velocity production system has been considered in the analysis using a mechanistic wellbore outflow model. A commingled reservoir inflow performance model was utilized in the analysis to evaluate the fluid inflow of multilayer gas reservoirs that may produce liquids in conjunction with the gas.