bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detecting Leaks in Abandoned Gas Wells with Fibre-Optic Distributed Acoustic Sensing
Authors: Boone K. , Ridge A. , Crickmore R. , Onen D. 
Published: May 2016

Abstract
Before any well is completely abandoned, some jurisdictions have governmental regulations which must be met and carried out by all companies. The main objective of these regulations is to prevent the production of oil and/or gas in the well by isolating and covering all porous zones. Monitoring with fibre-optic distributed acoustic sensing (DAS) systems allows for leak detection within the well bore and mapping migration through the cement with full-wellbore coverage. DAS provides a cost-effective method to accurately determine the depth of a leak or multiple leaks and profile gas movement due to casing failure, failure in wellhead seals, etc. In vertical wells or wells with low deviation, the optical fibre can be easily deployed by attaching a weight bar to the end of a steel tube containing fibre and running it to depth as a temporary installation or left in place as a permanent monitoring capability. Alternatively, a fibre that is already permanently installed behind the casing and cemented in place can also be used. Acoustic events from the gas movement produce a very small strain in the fibre. The strain can be measured at surface and depth-matched using the speed of light in the fibre. After characterizing the flow in the well under open and shut-in conditions, a decision can be made on how to address the leak. This paper will describe DAS technology and how it is deployed as well as show the analysis and results from a casing leak detection trial.

Introduction
DAS technology utilizes fibre optic cable as a distributed microphone, with high spatial resolution over long distances. In DAS, a short pulse of light is launched into the fibre, as a probe. During the manufacture of the fibre, imperfections created during the cooling of the fibre, cause variations in the refractive index of the glass. These imperfections are very numerous and randomly distributed, and are referred to as scattering sites. When the light probe advances down the fibre, a small portion of its light becomes scattered by the scattering sites. About 0.1%, of the scattered light gets captured by the fibre and is guided back towards the launch direction, and this backscattered light is detected by a detector within the DAS system.
Figure 1 shows the relationship between the launched light probe (in blue) and its backscattered response. At time t0, a light probe is launched into the fibre and the figure shows the interaction of the light probe with the fiber, causing backscatter, denoted by red arrows, at some arbitrary time, tn. At some later time tn+1, the backscattered response (in red) has propagated back towards the launch direction, and the light probe (in blue) has continued to propagate towards the end of the fibre. As the light probe propagates down the fibre, a continuous stream of backscattered is light is generated throughout the fibre. The light probe and backscatter detection process is referred to as interrogation.
Blended Source/Nodal Ocean Bottom Seismic Acquisition
Authors: Walker Chris , Hays David 
Published: May 2016

Abstract
Ocean bottom seismic (OBS) data have been used for appraisal and development applications for a number of years in the North Sea, West Africa, Gulf of Mexico, and more recently offshore Brazil and SE Asia but the scale of the surveys, by dint of their focus on field specific imaging, has been limited compared to towed streamer surveys in both size and duration. One of the challenges set by the oil companies has been to reduce the unit costs of OBS data - "If only the square kilometer rates were lower we would shoot more data" is a common mantra.
The difficulty in doing this has been the inherent technical downtime experienced by all the contractors operating ocean bottom systems - the terminations, connectors, power distribution and data telemetry components within a traditional ocean bottom cable (OBC) system are inherently prone to failure due to the intrinsic nature of the cable deployment/recovery cycle where the cables are stressed and de-stressed every time they are laid onto/recovered from the seabed. It is akin to recovering the full streamer spread every line change for towed streamer operations.
The desire to improve operational performance was the driving force behind the development of the Z700 autonomous nodal system and its extreme reliability has allowed ever larger seafloor spreads to be operated which has multiple benefits.

Operations
Since its commercial introduction in 2009 more than 250,000 Z700 (Figure 1) node deployments have been made in water depths ranging from 20 to 1200m in the Red Sea, North Sea and Gulf of Mexico.
Ensuring Safety Of Residents In An Emergency Planning Zone While Maintaining Sensitive Public Relations With The Affected Residents - Best Practices Shared.
Authors: Daher Elie , Dowd Darrell , Pye Don , Wicker Bob 
Published: May 2016

Abstract
Establishing an Emergency Planning Zone (EPZ) map lays the foundation for a successful Emergency Response Plan. A safety company was tasked with the responsibility of ensuring the safety of residents living in a neighboring community where potentially hazardous drilling activity in a critical sour well with high H2S concentrations and potential high release rates was about to commence. The safety company was responsible for managing and monitoring the EPZ while constantly updating residents about progress on the drilling activity.
An EPZ of 5.8 kilometers and an awareness zone of 11.6 kilometers were identified; the area of management contained one town and two hamlets of roughly 2000 inhabitants. To effectively monitor and ensure the safety of residents within the EPZ, the safety company dispatched and managed close to 100 onsite personnel. This large team was responsible for manning roadblocks, monitoring the various zones within the EZP, and maintaining buses on standby to evacuate low mobility groups.
Another key element of this project was the successful handling of crucial public relations to defuse and manage potentially very tense situations. The sensitive nature of the issue required careful, consistent and regular communications as residents needed to be constantly updated on the impending drilling operations. To handle the daunting community relations issues effectively, the safety company deployed a number of ‘rovers’ to monitor and communicate with the public through house visits. A call centre was also set up for residents to reach out for more information.
The project was so effectively managed that it even superseded the expectations of the regulatory body responsible for overseeing the drilling project. This paper will discuss in-depth details, learnings, insights and the various factors that were responsible for making this Emergency Response Planning project such a complete success.
Geologically Guided Prestack Depth Imaging - a Case History From Greater Burgan, Kuwait
Authors: Hafez Karam Mohamed , Mukherjee Pradip Kumar , Anandan Mudavakkat , Al-Ghareeb Aisha , Zahran Wael Abdel Alim , Saleh Tamer , Cunnell Chris 
Published: May 2016

Abstract
Prestack depth migration (PSDM) can provide superior seismic volumes even in areas of low relief structures. A pilot PSDM study over the Greater Burgan oilfield in Kuwait demonstrated not only the uplift versus prestack time migration (PSTM), but also pointed to areas of further improvement in the velocity model building workflow. A full field (FF) study was subsequently performed, and incorporated the lessons learned from the pilot. The main area for enhancement was the integration of geological information into the velocity model. This included near-surface velocity characterization and incorporation of existing 3D log-based velocity models into the initial PSDM model, plus implicit geological constraints during the model updating workflow.
The results were a more geologically plausible velocity model with enhanced imaging versus both the legacy PSTM and pilot PSDM volumes, establishing the FF PSDM volume as the main seismic volume for interpretation, well planning and reservoir characterization for the Greater Burgan field.

Introduction
The Greater Burgan oilfield is located in southeast Kuwait and is the main production field for Kuwait Oil Company (KOC), covering an area of approximately 850 km2. The geology is well documented (Carman, 1996), and is expressed as a broad, low relief anticlinal dome draped over a basement horst structure. The primary producing reservoirs are the Cretaceous-era Wara and Burgan sands (Figure 1), which are observed as a seismically quiet section with low acoustic impedance on the well logs. Deeper targets also exist in the Jurassic limestone reservoirs (e.g., Marrat).
A 3D seismic survey was acquired in 1997–98 covering an area of 1372 km2 using parameters commonly used at that time. This covered the complete Greater Burgan oilfield. Offset and azimuth distribution was mostly restricted to the inline direction (low aspect ratio survey geometry), which, in turn, imposes limitations on the utilization of full-azimuth information in the data processing and imaging sequence.
In 2010–11, a small test area was selected for a 3D PSDM pilot study. The aim of the pilot was to provide improved imaging compared to recent PSTM and a better input to ongoing horizontal and multilateral well programs. Particular attention was placed on enhancing the section between the primary reservoirs, the intra-reservoir clastic sequences, and imaging the minor faults that control compartmentalization. Key challenges included the near-surface complexity, characterized by rapid vertical and lateral velocity heterogeneity down to the Rus horizon (the shallowest mapped horizon in the field, between 200 and 500 m in depth, and consisting of high-velocity anhydrites), noise and multiple contamination of the legacy seismic data set, and reliable depth control of low relief structures across the pilot area.
New Approach To Hydrocarbon Migration In The Polish Carpathians Based On Outcrops Analyses
Authors: Lesniak Grzegorz , Irena Matyasik , Jankowski Leszek 
Published: May 2016

Abstract
The research was carried out in different tectonic units of the Polish Carpathians. Three stages of migration were indentified with the use of fluidal inclusions in cements analyses and bitumen traces in the pore space. The main migration paths of hydrocarbons are usually mélange tectonic zones revealing signs of diversified mineralization. These out-of-sequence thrusts may demonstrate the connection with the Carpathian basement. Location of hydrocarbons reservoirs along mélange and tectonic active zones, which form the flower structures, suggests the possibility of migration of hydrocarbons from the very deep zones subsidented within the Central Carpathian Depression (CCD) graben. Hydrocarbons generated at great depths migrates along mélange and active tectonic zones. These flower structure, consisting of network of fractures, in which crucial role in hydrocarbons migration plays the most active tectonic zone (so called master fault) plays a main role in hydrocarbons accumulation e.g. CCD margin zone is an essential element for the process of charging these flower structures with hydrocarbons. Mineralogical, petrographical and geochemical (bitumen extracts, biomarkers) analyses were performed on sediments trapped in mélange zones. Completed studies have shown diversified mineralization processes and bitumen type along the main zone of the tectonic mélange. This is related to the depth of mélange zone rooting and fluid migration from the Carpathian basement rocks. Determination of hydrocarbons generation, its nature and the origin of crude oil trapped in mélange zones have a great impact on new directions in oil exploration in the CCD area.
Theory and Experimental Setup of the New Rise In Core Reservoir Wettability Measurement Technique
Authors: Ghedan Shawket G. , Canbaz Celal Hakan 
Published: May 2016

Abstract
Reservoir wettability has direct impact on the relative movement of reservoir fluids and oil displacement efficiency by EOR techniques. The industry standard wettability laboratory techniques of Amott, USBM and modified Amott/USBM are very time demanding due to its complex experimental setup and procedure.
This paper describes the theory and experimental setup and procedure of a new wettability laboratory technique. Rise In Core, RIC, technique is based on a modified version of the Washburn Equation. The modified equation could be solved for the wettability contact angle by only substituting the slope of a fitted straight line of the square line of the square of core sample mass change with time, resulting from either water imbibition into oil saturated core sample, and/or vice versa. A constant of the equation, that is characteristic of the rock type, needs to be determined prior, however, by conducting an imbibition experiment of a reference liquid into air saturated twin core sample. The reference liquid completely wets the core sample with zero contact-angle.
The new technique was applied to measure the wettability of Berea sandstone core samples. The wettability of natural outcrop cores was found to be weakly water wet. Experiments conducted on neighboring samples, produced similar wettability result, indicating good repeatability. The applicability of the RIC in other wettability regions was also tested, resulting in repeated strong wetness for standards that were artificially treated to be either strongly water wet, and oil wet. The technique was also compared to the existing industry technique and proved to provide equivalent and more consistent wettability measurements for more than ten twins of carbonate core samples.
RIC technique is theoretically sound, and requires simple experimental setup and procedure. Moreover, it determines wettability in terms of contact angles rather than wettability index. It is more consistent and applicable to all wettability regions.
Integrity and Efficiency in LNG Transfer Operations with Flexibles.
Authors: van Bokhorst Evert , Twerda Aris 
Published: May 2016

Abstract
The work presented contributes to the LNG supply chain by the development of a validated calculation model for corrugated flexible hoses or pipes developed for LNG Transfer. The model builds upon experience gained by TNO Technical Sciences (Fluid Dynamics) in a large number of flow tests carried out on hoses in a large range of diameters from 4 to 18-inch.
LNG transfer rates are in general relatively high as the time involved should be limited from economical point of view. In large scale offshore LNG transfer, flow rates up to 5000 m3/h are applied and in future flow rates up to 10.000 m3/h are foreseen. Typical values mentioned for offshore operations in tandem transfer range from 50 to 150 meters hose length and hose diameter up to 20-inch.
The pressure losses in LNG offshore transfer, but also in smaller scale applications, can be considerable. The pressure loss depends on flow rate, length of the hose, internal diameter and internal hose corrugation geometry. High pressure losses will impose additional requirements on LNG pumps and might result in cavitation at the downstream end of the hose as the average pressure drops below vapor pressure.
Furthermore the impact of local boiling phenomena due to heat-ingress and cavitation, possibly effected by vortex shedding along the internal corrugations, is not known.
Once the gaps in the data base are filled a validated prediction model is available, which can be used in guidelines and standards. So far the EN1474 (part 2: Design and testing of transfer hoses) does not specify a maximum allowable pressure loss and the prescription of the requirement for the test is limited: "Flow rate testing (ambient or cryogenic): demonstrate that the hose is capable of operating at its maximum flow rate and confirm the predicted head loss"
The final goal of the project is to obtain a validated prediction model for the calculation of pressure losses in LNG transfer with flexible multi-composite and metal hoses based on input of parameters as operating conditions and hose geometry. Also input for guidelines and standards in LNG transfer with flexibles such as EN1474 will be generated, which can be used in for qualification of LNG equipment.
The Present-day stress pattern in the Middle East and Northern Africa and their importance: The World Stress Map database contains the lowest wellbore information in these petroliferous areas
Authors: Rajabi Mojtaba , Tingay Mark , Heidbach Oliver 
Published: May 2016

Abstract
Knowledge of the present-day stress field is vital for a range of earth science disciplines, including hydrocarbon and geothermal energy production, mine safety and seismic hazard assessment. The scientific importance of understanding the present-day maximum horizontal stress orientation has been demonstrated by the findings of the World Stress Map (WSM) Project, which has spent over 25 years building an extensive freely-available repository of present-day stress information as a collaborative project between academia, industry and government. The WSM project has revealed that the plate scale present-day stress is controlled by the tectonic forces exerted at tectonic plate boundaries. However, numerous studies in sedimentary basins have shown that stresses in the oil-patch can be complex, and controlled by both major far-field forces (plate boundaries, body forces from mountain belts) and intra-basinal forces, such as detachment zones, salt, faults and basin geometry.
The World Stress Map project contains free and public information for over 80 basins around the world. However, the project contains almost no wellbore data for the Middle East and Northern Africa, despite this region hosting much of the world&apos;s global oil production and extensive industry activity. To date, the World Stress Map Project only contains limited datasets from petroleum wells in Egypt, Oman and Iran - but no data at all for Saudi Arabia, Iraq, Libya, Algeria, UAE, Kuwait or Qatar.
In this paper we first review different methods for determining and calculating the present-day stress pattern in the region, then we highlight the lessons learned from the World Stress Map project on the controls of present-day stress in the oil-patch. Finally, we focus in detail on the stress data that currently exists for the Middle East and Northern Africa.

Introduction
Knowledge of the crustal present-day stress pattern is important for a range of earth science disciplines including:Geodynamic applications (e.g. Richardson 1992; Zoback 1992);Neotectonic and intraplate deformation (e.g. Tingay et al. 2005; King et al. 2010);Geomechanical characterization of petroleum basins (Tingay et al. 2005);Earthquake hazards (Sandiford et al. 2004), and;Rock mechanics and engineering (e.g. Reinecker et al. 2006; Zang et al. 2012).
The Present-day stress has numerous applications in petroleum basins, particularly in borehole stability, reservoir drainage and flooding patterns, pore pressure prediction, fluid flow in naturally-fractured reservoirs, hydraulic fracture stimulation, seal breach by fault reactivation and any geomechanical modeling. Hence, present-day stress analysis, as a part of 'petroleum geomechanics&apos;, has received extensive attention in petroleum industry in recent years (Barton et al., 1995; Sibson, 1996; Jones and Hillis, 2003; Rajabi et al., 2010; Tingay et al., 2010a and b).
Design, Implementation And Results Of An Inter-Well Chemical Water Tracers Pilot Test To Improve Water Flood In Complex Reservoirs
Authors: Cuauro Antonio , Frans Frederic , Knowles Dale , Wigley Paula , de Mas Carolina , Jevanord Kjersti , Al-sadah Abdulla 
Published: May 2016

Abstract
The use of water tracers to better understand and improve water flood performance has long been part of the reservoir management toolbox. Its use is even more relevant when applied to complex and heterogeneous reservoirs. This paper describes the planning and implementation phases of a chemical tracer injection pilot in the Al Shaheen oil field, offshore Qatar.
In Al Shaheen injection water has historically been used as natural tracer to identify inter-well communication in the field by analysis of the salt and ionic content of produced water. However, this approach has become less effective over time. Identification of short-circuits is getting more complex with the increasing number of wells completed.
A tracer pilot including chemical water tracers was designed to identify inter-well communication and flow paths of injected water in a complex area of the field. The geology of this area is highly heterogeneous, with a stacked sequence of carbonate and clastic reservoirs. Numerous features were identified as the possible cause of these inter-well communication paths, including faults and fractures, thief zones, permeable shale and/or absence of shale.
The pilot includes two water injection wells completed in two different reservoirs and twenty six oil production wells. This paper reviews the selection of the candidate wells, the operational constraints as well as the detailed analysis and interpretation of the results. Based on this pilot, interwell connection has been proven in most of the area of interest. Tracers have been detected in six of the twenty six wells, with breakthrough times ranging from three to seventy days. Communication between the carbonate and clastic reservoirs was confirmed in two wells. For some of the early samples, anomalous results were obtained. This has been attributed to contamination during sampling at the platform, and was remediated by improving the quality control during sampling.
This water tracer pilot paves the way for further application across the field. Ultimately the tracer results will be used in combination with other surveillance techniques to identify by-passed oil and design fit-for-purpose solutions to target higher recovery.