bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Utilisation of High-Definition Borehole Images to Determine Fracture Properties and Their Relative Age for Fractured Basement Reservoirs
Authors: Li Bingjian , Singam Thanapala , Kieu Pham Thi , Nam Thang Tran 
Published: March 2015

Abstract
Fracture data from borehole images has been a critical portion of well data for the fractured granite basement reservoir characterization for long in Vietnam. However, acquiring good quality electrical borehole images can be often challenging due to extremely high formation resistivity and also abnormal wide range of resistivity spectrum within the basement. A new imaging tool was introduced in the local basement wells recently to provide high-definition full-coverage electrical borehole images. The enhanced borehole images allowed better interpretation confidence and accuracy for fracture properties for the basement reservoirs.
There are a few case studies presented in this paper to illustrate some key improvements and applications of this new image data. First of all, the image quality enhancement from the high-definition tool is shown in comparison with conventional image data acquired from the same basement formation. Secondly, a case example is presented to show that accurate fracture properties derived from the high-definition images can help to better predict permeable zones with validation from dynamic data in the same well. Thirdly, examples on how to interpret relative fracture ages for the various sets of fractures developed in the basement using the new images are also discussed. Such fracture information potentially allows better understanding of the fracture/fault development as well as assisting geoscientists to build proper fracture models in the basement.

Introduction
The basement reservoirs in southern offshore Vietnam are naturally fractured with very tight matrix. Multiple fracture sets, developed under different deformation stages, provide permeability and part of storage capacity along with some other pore types like vuggy porosity associated with fractures or matrix-alike pore developed in the fault damaged zones. Such reservoirs are highly heterogeneous in terms of porosity distribution and permeability anisotropy.
Acquiring good quality microelectrical images in high-resistivity formations like granite basement can often be a challenge. Random noise sometimes obscured fine details or resulted in pixilated or "speckled" images in high-resistivity formations. An example of FMI* images from a basement is shown in Figure 1 to illustrate a few typical quality issues in the hard formations. First of all, the image can often have a "grainy" looking (or "speckled") background due to the tight matrix and very high formation resistivity, for instance in the low zone in Figure 1. Secondly, high level noise particularly in the zones with huge range of resistivity variation can result in geological features poorly defined. This can be also observed in the middle zone in Figure 1, where the vugs and fractures are not well defined due to high noise level (white spots) in the zone.
Drilling and Completion Technique Selection Methodolgy for Coalbed Methane Wells
Authors: Caballero J. 
Published: March 2015

Abstract
Geographically, coal-bed methane exploration or development has occurred on every continent with the exception of Antarctica. Worldwide, many different completion techniques have been utilized to develop coal-bed methane reservoirs. These techniques range from vertical well multi seam completions to multiple lateral wellbores drilled into a single coal seam. Stimulation techniques include open-hole under-ream, cavity creation, and hydraulic fracturing. A number of factors influence the selection of completion techniques including proximity to established oil and gas infrastructure, depth, number and thickness of coal seams, permeability, gas content, composition, and saturation, porosity, etc. The purpose of this paper is to survey the various techniques that have been utilized, to provide the rationale for utilization of each technique, to comment on the commercial success of the various techniques, and to propose a general selection criteria approach that may be useful in the selection of a drilling and completion technique.

Introduction
While CBM well drilling and completion permutations may be practically endless, the following summary descriptions will be covered in this paper: Vertical well, open-hole and under-ream completion, single seamVertical well, cased and open-hole, perforate and under-ream completion, multi-seamVertical well, open-hole cavity completion, single seamVertical well, cased perforated, hydraulic fracture completion, multi seam
Plug and Perforate Ball and Baffle Multiple Zone Stimulation Technology (MZST)Vertical well, open-hole under-ream with intercepting single or multiple surface to in-seam open-hole horizontal well(s), single seamVertical well, open-hole under-ream with intercepting a surface to in-seam open-hole multi-lateral horizontal well
Other techniques not listed here can generally be considered to be a variation or combination of one or more of these techniques. Many authors have proposed methods for determining the optimum drilling and completion method [1, 2, 3]. These methods have consisted of flow diagrams, empirical studies, and reliance on a few critical reservoir parameters and form the basis for conceptual understanding of the problem. This paper will present an overview of the various CBM drilling and completion techniques; reservoir parameters that need to be considered in the selection of drilling and completion techniques; and a proposed methodology for selecting optimum drilling and completion techniques will be proposed.
The Development of a Workflow to Improve Predictive Capability of Low Salinity Response
Authors: Suijkerbuijk B.M.J.M. , Kuipers H.P.C.E. , Van Kruijsdijk C.P.J.W. , Berg S. , van Winden J.F. , Ligthelm D.J. , Mahani H. , Pingo Almada M. , van den Pol E. , Joekar Niasar V. , Romanuka J. , Vermolen E.C.M. , Al-Qarshubi I.S.M. 
Published: March 2015

Abstract
Low Salinity Waterflooding (LSF) is an emerging improved oil recovery (IOR) technology that has been shown to work in a number of cases, while sometimes - unexpectedly - no incremental oil production is observed. Industry has not yet reached consensus on the mechanism behind LSF, which precludes effective screening and prioritization of LSF candidate fields.
In this paper a workflow is introduced that improves the way fields are screened for their LSF potential. It employs closely interlinked experiments and modeling work from the molecular scale to the macroscopic Darcy scale, thereby closing gaps that previously impeded the predictability of the low salinity effect. The new workflow is based on the notion that wettability is a surface phenomenon. Elucidation of the low salinity mechanism should thus not be based on bulk measurements, but rather on the characterization of surface compositions and forces.
The main insights that follow from this work are:Application of successful LSF leads to a wettability modification towards more water-wet, which is consistently observed at the atomic scale and at the core scale;The surface alterations that occur during LSF correlate with macroscopic observations such as oil recovery from core plugs;The time scales involved in wettability modification towards a more water-wet state can easily be long enough to lead to false negatives in common SCAL experiments;
It is demonstrated that double layer expansion (DLE) is likely behind the low salinity mechanism, as processes involving cation exchange are expected to only occur long after breakthrough of the low salinity bank.
Even though the workflow has been developed for LSF in sandstones, it is also being employed for LSF in carbonates. The fundamental insight that surface properties dominate the response does not only impact how LSF research and related SCAL experiments are being conducted, but impacts all other EOR processes relying on interfacial phenomena, as well as oil field science in general.
Novel Applications of Formation Testing to Optimise Field Redevelopment Program and Gas Injection EOR Project in Matured Fields
Authors: Guo Q. , Xiao C. , Zhao Y. , Chen J. , Xian C. , Zhuang X. 
Published: March 2015

Abstract
Formation testing has been utilized widely worldwide as well as in China for field exploration and appraisal, helping reservoir characterization and evaluating hydrocarbon reserve. However, using formation testing technology at development stage in order to improve the reservoir ultimate recovery is not mentioned much in published literatures. In this paper, two case studies were summarized on how formation testing was used at the secondary and tertiary stage of development field in west China including the first domestic gas injection monitoring application.
HD Field is one of the oilfields of PetroChina which contributes significant oil production in Tarim basin. With strong aquifer support, one challenge in the adjustment of oilfield development plan is to identify how a potential zone has been water flooded. This case study demonstrates how data acquired from the formation testing helps reservoir engineering study, revises the field development plan and eventually identify the new wells locations with encouraging production result.
The second case study demonstrates the first ever application in China of gas injection monitoring in field YH. This field is rich of gas condensate and utilizes gas injection as the main approach to drive the field production and to maintain the reservoir pressure. Because of commingle gas production from multiple zones; it is challenging to understand the sweeping efficiency of injected gas from different formation. With the help of real time downhole fluid composition measurement and innovative new designed probes, formation testing is able to pin point zones that have been swept by injected gas. So the gas injection strategy was adjusted accordingly to improve the overall field recovery.
Optimizing Operational Performance of Riser Systems Through Improved Understanding of Riser Thermal Behaviour
Authors: Sarkar Suranjan , Moeleker Piet , Kotikanyadanam Mohan , Chin Grace , Schwing Alex , Henkes Ruud , Zabaras George 
Published: March 2015

Abstract
One of Shell's deepwater projects has decided to use the cost-saving Single Casing Combo Top-Tension Riser with nitrogen insulation for the Tension Leg Platform (TLP) dry-tree wells to reduce the overall riser cost and TLP payload. However, the thermal performance of such a riser is poorly understood and an accurate prediction model was not available. A conservative thermal-hydraulic design approach would result in redundant requirements for the flow assurance chemicals and unnecessary challenges for the TLP operations. Numerical and experimental work was carried out to better understand and predict the riser thermal performance during startup, normal operation, and shut-in conditions. This paper described the numerical and experimental results. The overall heat transfer coefficients (U-values) from the detailed numerical simulations and experiments were used to derive the effective thermal conductivity (keff) of the nitrogen in the annulus, which includes the effect of all three modes of heat transfer (i.e. conduction, radiation and convention). This effective conductivity for the nitrogen gas was used in a one-dimensional model for the riser. The results of that model give the operator confidence in the system design and operability. The main benefit for the project is less chemical storage weight and space required on the TLP. The experimental and numerical model, with some modifications as required, can be used to optimize performance of riser systems in other projects as well.

Introduction
Single casing combo top-tensioned riser (SCC-TTR) for deepwater oil and gas developments
The development of deepwater oil and gas reserves constantly faces the challenge to reduce costs and complexity of the operations involved. This requirement increases the attraction of dry tree floating production facilities such as Spars and Tension Leg Platforms where direct accessibility of the wells below the production platform is possible. Dry tree units will continue to be the favored development approach for deepwater and ultra deep water developments [1]. Top-tensioned Risers (TTRs) have been in service on floating production facilities with either TLPs or Spars as the host vessel. A TTR primarily consists of a production tubing and casing(s) and it may be of the single casing or dual casing type. The single casing combo TTR (SCC-TTR) consists of a single casing and internal production tubing. This arrangement has the smallest diameter and offers the lightest solution with lowest capital cost.
The Damage Appraisal on Elemental Sulfur Deposition in High Sulfur Content Gas Reservoirs
Authors: Yang Xuefeng , Hu Yong , Zhong Bing , Yang Hongzhi , Wang Songxia 
Published: March 2015

Abstract
Research on the elemental sulfur deposition belongs to one of the most important tasks in the development of high sulfur content gas reservoirs. In order to evaluate the formation damage from elemental sulfur deposition in the developing process of the sour gas reservoir accurately, experimental procedures are devised to establish measurement method for determining elemental sulfur deposition by purchasing corresponding experimental accessories. The quantitative research on the elemental sulfur deposition is carried out for the first time at home and abroad. Natural carbonate cores and over-saturated natural sour gas are adopted to observe sulfur precipitation and plugging in the sulfur precipitation damage experiments, which is conducted under the condition of pressure and temperature close to actual reservoir as much as possible. Results illustrate that the sulfur deposition in core has little effect on the porosity with pressure decreased, but great impacts on the permeability. The damage factor of permeability increases with rising initial pressure, and temperature has rarely influence on the sulfur deposition with the same initial pressure. Furthermore, the declining permeability of core results in increasing the damage to the permeability, which means sulfur deposition will cause more harm in low permeability formation. Therefore, it is essential to lay full emphasis on the sulfur deposition during the development of sour gas reservoirs. The reasonable and efficient development strategy can be achieved by alleviating the elemental sulfur deposition as far as possible.
With the expanding energy contradiction between the supply and demand in the world, the development of high sulfur content gas reservoirs has caught more and more attention in public. However, the dissolution and deposition of elemental sulfur will take place during the developing process of sour gas reservoirs, compared with sweet gas reservoirs. The elemental sulfur solubility in sour gas decreases with the descent of formation pressure, the elemental sulfur will precipitate once the sulfur content exceeds its solubility. The precipitated sulfur will block the formation pore and reduce its permeability, which leads to lower the capacity of gas well seriously and even brings great detriment to the normal production and management of gas well. So far elemental sulfur deposition researches are mainly concentrated on oil reservoirs, papers about sulfur deposition experiment in sour gas reservoirs has not been published yet. Consequently, experimental procedures are devised to establish measurement method for determining elemental sulfur deposition by purchasing corresponding experimental accessories. Experiment of elemental sulfur precipitation in core is carried out for the first time at home and abroad, which lays the foundation for the further research on the safe and reasonable development of high sulfur content gas reservoir.
Formation Testing: New Methods for Rapid Mobility and Pore Pressure Prediction
Authors: Zhou Yanmin , Zhao Lixin , Feng Yongren , Yu Qiang , Chin Wilson 
Published: March 2015

Abstract
Fast and direct measurements for pore pressure and mobility are crucial to accurate formation evaluation, economic analysis and drilling safety. Real-time predictions can be obtained from formation tester pressure transient analysis. However, in tight sand and heavy oil environments, this is hampered by conventional approaches which require steady-state pressure responses that may require hours of wait time. These imply prohibitive offshore costs and increase the risks of stuck and lost tools; the methods derive from decades-old formulas intended for high-mobility formations which equilibrate rapidly. New math models are introduced that, now assuming high levels of pressure diffusion, require just seconds to yield acceptable pore pressures, and vertical and horizontal permeabilities. These augment traditional methods, providing suites of pressure evaluation tools covering all permeabilities; moreover, they do not require hardware changes to existing tools aside from downhole firmware modifications. For dual-probe tools, we develop analogies to resistivity logging: pump pistons are oscillated sinusoidally, and pressure phase and amplitude changes monitored at observation probes are interpreted using Darcy's law. Second, parallels to sonic logging are considered: pistons are allowed to impact formations suddenly, and signal arrival times measured at observation probes are converted to mobility. Third, for dual and single-probe systems, rapid "drawdown alone" and "drawdown-buildup" approaches that do not use exponential, transcendental or complicated error functions, but instead, efficient rational polynomial expansions, are described. Detailed examples and validations demonstrate the power and versatility behind the new methods for real-time and job planning applications. Fast calculations support increased downhole data usage, thus enhancing real-time capabilities; they free up resources needed to support other MWD/LWD functions. We also provide a photographic survey of newly developed wireline and "while drilling" formation testers that make use of the fast interpretation models and introduce the reader to new reservoir description capabilities.

Introduction
Formation testers, originally developed for fluid collection, are now widely accepted reservoir description instruments, providing detailed borehole information related to permeability, mobility, anisotropy and pore pressure. These objectives are met using pressure transient analysis models which interpret unsteady flowline changes with specially developed math models. Different designs are available from service companies. A cross-section of tools serving different logging applications developed by the present organization and its oil service subsidiary is shown in Figures 1a and 1b.
Field Trial Results of a Drilling Advisory System
Authors: Chang Dar-Lon , Payette Gregory S. , Pais Darren , Wang Lei , Bailey Jeffrey R. , Mitchell Nicholas D. 
Published: March 2015

Abstract
Field tests of a real-time Drilling Advisory System (DAS) have demonstrated value in several drill well surveillance applications. This system receives drilling data and transmits recommended operating parameters to the driller using existing rig systems and Wellsite Information Transfer Specification (WITS) data records. Using this industry standard, DAS can be deployed to any suitable data acquisition system on the diverse rig equipment available in the industry. The DAS computer may also be connected to a company network to enable desktop viewing of the drilling recommendations in the office.
The method embodied in the software comprises both a learning mode and an application mode. In learning mode, systematic changes in parameters are recommended to explore the operating space, and calculation of an objective function determines results. Complex decisions to change operating parameters such as weight on bit, rotary speed, and flow rate can also be made with the assistance of DAS via early detection of drilling dysfunctions which change with depth and formation.
The operator's ROP (Rate of Penetration) management process is focused on MSE (Mechanical Specific Energy) surveillance, and the DAS process extends this methodology to a real-time operating system. DAS is designed to assist the driller by capturing and organizing real-time data without imposing on their judgment and control. It is intended to be a digital helper that enhances the driller's ability to interpret current drilling conditions and make effective decisions.
Remote access capabilities and customized output to the driller's display were demonstrated in field trials, and key lessons from field trials have been implemented. The field trials included multiple hole sections in onshore and offshore wells across a wide variety of drilling conditions. In one example provided in this paper, the use of DAS provided 35% higher ROP when DAS was used to avoid drilling dysfunctions.

Introduction
In a recent paper by Dupriest and Koederitz from the 2005 SPE/IADC Drilling Conference ("Maximizing Drill Rates with Real-Time Surveillance of Mechanical Specific Energy": SPE 92194), Figure 1 was presented to illustrate the three basic regions on a drilling response curve. The chart shows that although operating above the founder point may provide slight increase in ROP, the system is operating in dysfunction and the WOB should be reduced to eliminate the dysfunction.
An Experimental Investigation on Archie Parameters at Ambient and Overburden Condition of Iranian Clean Carbonate Reservoir Rock and Developing a new Formation Resistivity Model for Limestone and Dolomite Samples
Authors: Eshraghi Ehsan , Moghadasi Jamshid 
Published: March 2015

Abstract
Electrical resistivity measurement is widely used to estimate porosity and water saturation. Archie equation is not easy to apply to carbonate rocks because formation parameters (a, m, n) are functions of changes in the pore geometry, clay content, tortuosity of the pores, as well as formation pressure. The Archie equation is also valid only when the rock is strongly water wet and clay free, which is not the case in carbonate rocks, therefore cannot be generalized over the entire carbonate reservoir, so the straightforward application of that in carbonate rocks has severe limitations.
In this paper, we discuss a new method using saturation analysis data to derive the correct form of the Archie equation that can be applied to carbonate rocks. Correlations among resistivity, and porosity derived from 108 actual core data of 18 core samples (10 dolomite and 8 limestone samples) in 6 different overburden pressures. The generalized equations can then be applied to any carbonate formation with varied geometry and clay content. The results of this comparison showed that the new developed model gave the best accuracy with average absolute errors of 20.4% and 10.9% for dolomite and limestone samples respectively, while the other common models are ranked, according to their accuracy in the following order to be Humble, Archie, and Shell, with average absolute errors of 26.0%, 26.7%, and 32.6% respectively for dolomites samples and in order to be Archie, Humble, and Shell with average absolute errors of 12.2%, 22.3%, and 26.2% respectively for limestone samples.
The advantages of this model is improving the accuracy of formation resistivity calculations by exerting the overburden pressure effect and specially usage of each formula for each mineral type.