bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Stimulated Reservoir Volume Using the Concept of Shale Capacity and its Validation with Microseismic and Well Performance
Authors: Ouenes A.. , Bachir A.. , Boukhelf D.. 
Published: June 2014

Abstract
The concept of SRV was supposed to represent the reservoir volume affected by the fracing and the proppant placement but end up being used as the microseismic stimulated reservoir volume which is usually a much larger volume. Given this large difference, many authors resorted to creating new concepts of SRV adapted to the problems at hand mainly the estimation of reserves. Most of these new concepts rely on the use of microseismic which still has a lot of issues to resolve before being a standard input in shale reservoir simulation and reserve estimation.
To reduce our dependence on microseismic data which is only available in about 5% of the shale wells, a new workflow based on "hard" G&G data is introduced for the estimation of SRV and its varying rock properties in a reservoir simulator. This new workflow relies on the use of the concept of Shale Capacity which encompasses the four key shale drivers responsible for most of the factors affecting the shale well performance: TOC, Brittleness, Fracture Density and Porosity. The shale capacity is available over the entire 3D reservoir volume and is estimated from well and seismic data.
The SRV varying enhanced permeability is estimated through a linear relationship that links the well test measured (PTA or RTA) permeability with the shale capacity thus providing realistic values to the reservoir simulator. Using appropriate gridding techniques such as the Tartan grid for the SRV cells, nearwellbore effects could be accounted for along with no Darcy effects and gas desorption in the shale reservoir. With these key factors represented in the dynamic model around the well, a Marcellus gas and water rate was successfully matched without the need for any major history matching effort. The resulting gas saturation and pressure distribution indicate that the naturally fractured shale matrix cells do contribute to the reserves which are not limited to the nearwellbore SRV cells where the proppant was successfully placed.
Distribution of Well Performances in Shale Reservoirs and Their Predictions Using the Concept of Shale Capacity
Authors: Ouenes Ahmed 
Published: June 2014

Abstract
Various empirical observations have been made regarding the nature of the distribution of shale productivity and the potential existence of three dependent intervals that seem to separate the uneconomical wells from the average and good wells. The areas of good well productivity exhibit a log normal distribution and seem to be controlled mainly by the natural fracture system. These differences in performance seem to be related mostly to the shale capacity defined as the product of four key shale drivers: TOC, porosity, brittleness, and fracture density. When drilling a shale reservoir, it appears that the Relative Intercepted Shale Capacity (RISC) seems to have a strong correlation with the resulting relative well performance. Consequently, well productivity could be predicted in a relative sense with reasonable accuracy if the 3D shale capacity model is available to the operator. Having such a 3D model available, a shale operator can compute the RISC of his future wells and adjust their landing zone, azimuth and length accordingly to reduce drilling and fracing costs, to achieve the best return on investment and accelerate the time to payout.
Integrated Thermal Gas Production from Methane Hydrate Formation
Authors: Sasaki K.. , Sugai Y.. , Yamakawa T.. 
Published: June 2014

Abstract
An integrated thermal system, named "Gas to Wire System", for gas production from methane hydrate (MH) layers and generating electricity has been presented based on a balance of waste heat of power plant and dissociations heat of MH including heating the MH layer with hot water. Firstly, gas production by the depressurization method was discussed based on the heat balance between MH dissociation heat and latent heat generated by decreasing of MH equilibrium temperature. The ideal initial MH saturation, showing the maximum one to get 100% gas recover-factor, was obtained as around 16%, even if 6 MPa depressurization is applied for a MH layer. Thus, the depressurization method may be applied for MH layers with low MH saturation less than 20%. The gas production system by injecting hot water from the plant and MH layers using a pair of dual-horizontal wells were modeled and simulated numerically. In the MH reservoir, a dissociated region flowing hot water between dual-horizontal wells, namely hot water chamber, was generated to produce gas continuously. Numerical simulations on MH gas production by hot water injection into a MH layer at Eastern Nankai Trough have been carried out by STARSTM with a pair of dual-horizontal wells 500m in length drilled in the methane hydrate layer of 20 m in layer thickness. Furthermore, a gas production scheme, which uses flow direction changes with four pairs of dual-horizontal wells in radial arrangement in a MH layer with area of 1 km2 located at Eastern Nankai Trough, has been presented, and its production performance was evaluated by the numerical simulation as the cumulative gas production for 15 years is 1.3× 108 std-m3. Finally, total heat balance of the MH gas production system has been investigated, and the waste heat of power generating plant can provide enough heat to increasing MH layer temperature and MH dissociation.
A Review of the Fundamentals of Shale Gas Evaluations: The Dangers of Effective Porosity and Clay Excess Conductivity Corrections
Authors: Glorioso J. C. , Rattia A.. , Lolley R.. 
Published: June 2014

Abstract
This paper addresses the problems identified in current shale reservoir characterization practices. We also provide alternative approaches with relevant reflections on the determination of volumes in-place. It is hoped that this paper will stimulate further discussion on the subject and prompt industry to revise current practices.
It is widely recognized that the accurate estimation of rock properties in unconventional reservoirs such as shales is of paramount importance. These property estimates are used for original fluid in place determination, reconciling recoverable volumes of forecast production, well spacing, completion design and many other applications. By comparison with conventional reservoirs, fluids are present not only in the intergranular porous media but also within the fine texture of the rock matrix (Clays, Kerogen and Micro-Fractures) which usually are only recoverable with the aid of suitable stimulation and completion technologies. This paper questions current engineering practices related with the assumption of unrealistic cut-offs in the petrophysical analyses which in turn may result in dangerously misleading estimates of in place volumes and thus inadequate development decisions being made.
The adsorption capacity of clays has been documented in the literature together with observations on the correlations between the percentages of clay minerals in the rock and Langmuir volume (VL) determined in laboratory measurements of gas content from core samples by means of Langmuir isotherms. Therefore it should be no surprise that clays in shale gas reservoirs are known to adsorb hydrocarbon gases and may contribute to the production when properly stimulated. We therefore recommend that corrections for clay effects should not be arbitrarily applied in the petrophysical analysis of electric logs. The use of a total porosity-total water saturation model will help to avoid shortcomings in total gas in-place determination.
There are additional reasons for the avoidance of clay porosity corrections; these include the fact that we have no reliable method to establish clay conductivity at reservoir conditions and we have no tools capable of differentiating between free gas and adsorbed gas. Both of these problems are limiting factors in the correct selection of porosity and water saturation parameters.
Total porosity and water saturation methods give rise to total gas content estimates using the appropriate volumetric model. Adsorbed gas content estimates may be obtained by correlating geochemical data based on gas content from laboratory experiments (which will include both kerogen and clay contributions) and rock density measured on core and or logs. When total porosity and total water saturation models are properly used in shale gas reservoirs characterization, the amount of free gas will be obtained as the difference between total gas content and adsorbed gas content.
A Conceptual Shale Gas Field Development Plan for the Lower Jurassic Posidonia Shale in The Netherlands
Authors: Godderij Raymond , Harings Michiel , Scheffers Berend , Brolsma Maarten-Jan , Bouw Sander 
Published: June 2014

Abstract
In preparation for potential exploration success in the Lower Jurassic Posidonia shale gas play in The Netherlands, EBN decided to investigate the possibilities and conditions of a commercial shale gas development in the area concerned. To this end, a thorough inventory and cost analysis of all activities, that are needed to develop such a shale gas play, formed the basis for an assessment of the most relevant subsurface & surface as well as commercial conditions for success. Detailed evaluations of cores, logs and ditch cuttings, detailed fracture modeling, production forecasting, planning of wells, well designs, well pads and locations, evacuation routes and project scenarios (single or multiple drilling rigs) formed part of the study.
Apart from the technical and commercial parameters, environmental and legal concerns needed to be addressed. The impact of the industrial activities on the physical and social environment in a densely populated area was mapped. Mitigating/impact reducing opportunities were investigated to assure legal requirements could be met in order to obtain the necessary permits from local, provincial and national authorities and to comply with European rules and regulations.
Study results indicate that economical shale gas development would be feasible in The Netherlands under the applied working assumptions.
New Dynamic Rock Test System to Assist in Planning and Creating Multidirectional Fractures
Authors: Surjaatmadja Jim B. , Looper David W. , Coffman Kenneth R. , Meadows David L. 
Published: June 2014

Abstract
In the oil field, rock testing (beyond standard core analyses) is generally limited to three classes—flow tests to determine the production characteristics of the rock in question, chemical tests to determine reactivity of the rocks, and testing the mechanical qualities of the rock to determine the resistance of the rock to forceful intrusions, such as drilling, perforating, and stimulations. Tests to determine mechanical qualities are mostly limited to static or steady state conditions; for example, Young's moduli and Poisson's ratio measurements, compressive strengths, tensile strengths, or anything that offers easily understood and useful data.
This paper discusses the creation of a new test process in which time is used as an aspect of the rock mechanics science in the oil field. For example, a question such as "how much pressure is required to fracture the rock" is henceforth replaced by a question such as "how long does it take for the rock face to move from point ‘A’ to point ‘B’?" To do so, rock testing facilities must be reformulated to include accurate motion monitors and sound detection for live capturing of events within the rock at accurate time steps, such as microseisms, etc. The paper also discusses the use of this technology to plan and create different methods of fracture stimulating a formation; in particular, creating multidirectional fractures to maximize well production is discussed.
Experimental Investigation of Decalin and Metal Nanoparticles-Assisted Bitumen Upgrading During Catalytic Aquathermolysis
Authors: Hendraningrat Luky , Souraki Yaser , Torsœter Ole 
Published: June 2014

Abstract
Unconventional oil reservoirs such as heavy oil, extra heavy oil, oil shale and oil sand/bitumen are very interesting since these kinds of oil are currently proven to constitute a huge amount of total world oil reserves. However, it is difficult to handle these kinds of oil due to very high viscosity. Thermal application methods may have great possibilities for heavy oil and bitumen production. Prior to shipment to downstream markets, the bitumen needs to be upgraded to produce higher value of liquid hydrocarbon products. However, the issues in oil sands industry are environmental challenges such as green-house-gas (ghg) emission, huge amount of fuel and water consumption, liquid and solid wastes disposal. The objective of this study is to investigate an effective and efficient upgrading process by adding decalin as hydrogen donor, water and various type nanometal particles (40-500 nm) as catalysts into Athabasca bitumen.
Athabasca bitumen has been successfully upgraded by reducing its viscosity about 80% (measured at 60 °C) by applying catalytic aquathermolysis at 240 °C during 12 hours. As hydrogen donor, decalin is very interesting. Besides cheap, it could dramatically accelerate viscosity reduction with concentration of 5 wt.%. The degree of viscosity reduction will increase with increased decalin concentration. However degree of bitumen upgrading will decrease with presence of water. It seems that synergetic effects to the upgrading process did not work effectively. Hence water consumption during aquathermolysis process might be reduced to minimize the cost. Since earlier studies have shown that nanoparticles may reduce heavy oil viscosity, four types of nanometal particles have been studied and some of them accelerated viscosity reduction during catalytic aquathermolysis process at particular concentration. Improper nanometal particle type and concentration are reversed effect. Temperature and heating time have vital role in the upgrading process.
Seismic Frequency Versus Seismic Interval Velocity Based Pore Pressure Prediction Methodologies for a near Salt Field in Mississippi Canyon, Gulf of Mexico: Accuracy Analysis and Implications
Authors: Mannon T. , Salehi S. , Young R. 
Published: June 2014

Abstract
Oil and gas plays are continuing to move into increasingly hostile drilling environments, including near and/or sub-salt proximities. The ability to reduce the risk and uncertainly involved in drilling operations in unconventional geologic settings starts with improving the techniques for pore pressure modeling. Nearly all of the modern day pore pressure prediction methods utilize interval velocities from seismic surveys to detect abnormal pressure along a proposed wellbore trajectory. Seismic interval velocities have long been known as being sensitive to formation properties such as lithology and porosity which may give way to erroneous pore pressure values; additionally, salt intrusions have proven to be a significant hindrance when predicting pore pressure from seismic interval velocities. A relatively new approach, which predicts pore pressure by way of seismic frequencies, has addressed the pitfalls seen in seismic interval velocity applications. With the goal of offering a valid seismic-based alternative to pore pressure prediction, a study has been conducted in a near-salt field in deepwater Gulf of Mexico that will compare and analyze the accuracy of seismic frequency versus seismic interval velocity based methodologies for pore pressure prediction. For the first time in the literature, the outputs between the two seismic models will be quantitatively assessed for accuracy. Accuracy standards will be based on the agreement of the seismic outputs to pressure data obtained while drilling and petrophysically based pore pressure outputs for each well. The results will show significantly higher accuracy for the seismic frequency based approach in wells that were in near/sub-salt environments and higher overall accuracy for all of the wells in the study as a whole.
New Generation of Sour Service Drill Pipe Allows Addressing Highly Sour Field Challenges
Authors: Rodrigues Ricardo , Flores Vincent , Thomazic Aurelie , Thebault Florian 
Published: June 2014

Abstract
With the increasing demand of gas worldwide, some highly sour oil and gas reservoirs have been explored in Russia, Middle East, China and North America. The development of such fields, which contain a high percentage of sour gas, represents significant technical challenges regarding drill pipe integrity and operations safety. Sour service drill pipe have long been used with tool joints and tubes meeting separate criteria for sour service as defined by several industry standards. This solution is still acceptable today for most of the current fields. However, the new challenges associated with the particularly sour fields require new highly engineered drill string solutions in order to increase the safety margin related to Sulfide Stress Cracking (SSC) failure risks, especially in the welded zones.
Drill Pipe are commonly produced by assembling pipe and tool joins through friction welding. The weld, as a result of this process, presents, nevertheless, some challenges for preserving SSC resistance due to some metallurgical factors such as heterogeneous microstructure, different chemical compositions between the tool joint and the pipe body and high hardness values close to the welded line. Hence a new drill pipe configuration has been developed including modified chemical composition and modified manufacturing process. These modifications allow for the improvement of mechanical properties performance and SSC resistance in the welded zone.
Fracture Gradient from Leadoff Test: Pitfalls of Using LOT Data from Non-vertical Wells
Authors: Rai Udai Bhan , Ghodke Nikhil , Schutjens Peter , Shete Kaustubh 
Published: June 2014

Abstract
Leak off tests (LOTs) are a routine in the drilling industry, typically conducted after drilling a few feet below a new casing shoe. The leak off pressure (LOP) recorded during a LOT primarily establishes the upper mud weight (MW) limit for the next hole section. Additionally, it can help to determine the cement integrity and the minimum total principal stress, which is close to the minimum horizontal stress in normal or strike slip faulting regime. The maximum operating mud pressure is usually maintained slightly lower than the LOP to permit safe well-control operations.
Field-wide LOP data generally show some spread at a given depth. The lower bound trend of LOP data is often used as the base case for fracture pressure prediction and for planning of future wells. For the field under investigation, values of LOP obtained at the 9 5/8" casing shoe showed a scatter of 1200 psi (3 ppg mud weight equivalent). The average depth of the casing shoe is ∼7900 ft and the LOTs are spread over a depth interval of only 260 ft.
Taking the lower bound of a wide spread in LOT data for fracture gradient estimation may lead to an overly conservative well design, because the difference between the pore fluid pressure and the LOT-based fracture pressure is (too) small. This so-called "small drilling window" can constrain casing design and mud weight. For example, when exploring deeper HPHT prospects, an excessively low (so conservative) fracture pressure estimate may increase the number of casing strings needed to reach the target. This can significantly change the well and drilling economics, and put the exploration/drilling plan at risk.
The study investigated the scatter seen in the LOPs to understand the cause of scatter in terms of rock mechanics, well trajectory and in-situ stresses. The redistribution of stresses around the borehole is known to depend on the orientation of the borehole with respect to in-situ stresses. This affects the measured LOP. Using rock mechanics models and field data, the study confirmed that LOP measured in inclined wells may need an adjustment (numerical correction) prior to use for predicting fracture pressures for future wells with a different trajectory (inclination and/or azimuth). The study also provides an understanding of the cause of losses reported in some wells in the field.
Threat and Error Management: The Connection Between Process Safety and Practical Action at the Worksite
Authors: Thorogood JL , Crichton MT 
Published: June 2014

Abstract
High Reliability Organisations have five important characteristics: a preoccupation with failure, a reluctance to simplify, sensitivity to operations, resilience, and a respect for expertise. Experience from recent incidents suggests that these qualities may generally be lacking in organisations that manage drilling operations today. Research sponsored by OGP and others has suggested that creating a sense of ‘chronic unease’ in relation to barrier integrity and operation of safety-critical systems, combined with understanding of the psychological issues that create error-producing conditions, will strengthen defences against major accidents occurring. The question remains as to the best way to embed the necessary skills through teaching, coaching, and assessment and their integration into routine working practices.
Experience from aviation suggests that successful implementation of non-technical skills needs to be combined with a clearly defined operational framework. Such an operational framework, however, is not widely observed in the drilling community at present. A standardised approach that defines how drilling operations are to be executed, activities monitored, decisions made or changes managed in a time-constrained environment provides the context in which the necessary individual and organisational skills can be taught. Training needs to address the underlying psychological theory, in particular cognitive biases, of non-technical skills to counter threats and errors in the workplace.
The paper summarises the principles of high reliability organisations and their contribution to process safety in the context of drilling operations. Next, we describe Threat and Error Management, which evolved from aviation-based Crew Resource Management to produce the levels of safety that today we accept as normal. We introduce operational risk management in drilling as the analogous link with aviation. The paper concludes by illustrating how these concepts can be used in drilling operations to enhance routine risk management activities, and will describe the tools and techniques involved.
The advantage of this approach is that effective non-technical skills can be observed, coached and assessed on a routine basis in the workplace. Active use of these methods in every-day drilling operations promotes the essential characteristics of a high reliability organisation by instilling the sense of chronic unease and concern for barrier integrity, thereby reducing the chance of minor anomalies cascading into major accidental events.