bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Induced Hydraulically Fractured Wells in Shale Reservoirs Using ‘Branched’ Fractals
Authors: Al-Obaidy R. T. , Gringarten A. C. , Sovetkin V. 
Published: October 2014

Abstract
Reservoir simulation has gradually become one of the most advanced methods for historical performance analysis and production forecasting for most conventional reservoirs. Unconventional fractured reservoirs still present a formidable challenge to simulate. Simplified reservoir modeling techniques are widely used at present. The recent development of liquid rich gas shale fields presents a new spectrum of problems for numerical modeling in terms of adequate description of in-situ rock permeability, geometry of the induced hydraulic fractures and long-term retrograde behaviour of gas condensate.
Most commonly used simulation models of fractured wells rely on multiple transverse planes each representing a single stage hydraulic fracture to form a network of fractures perpendicular to the wellbore (Vincent, 2011). This approach has difficulties in describing pressure distribution along a single fracture and also within the corresponding drainage area. As a result, the magnitude of pressure depletion and condensate drop-out appear uniform across the fracture-reservoir systems. This can often lead to over-estimation of the rock permeability as well as the contacted reservoir volume.
The focus of this research was on the Kaybob rich gas / retrograde gas condensate region of the Duvernay Shale that is currently being developed in Alberta, West Canada. An actual active production well was used to set up simple ‘branched fractal’ simulation models which were aimed to represent alternative topologies of a "typical" induced hydraulic fracture. Fluid properties, well completion information and production data were used to build and history matched the model over the 2-year historical period.
The simulations demonstrated that fracture geometry had a substantial impact on predicted condensate rates for the same amount of gas production. Differences in reservoir pressure patterns around the fracture segment and the resulting variations in condensate bank build-up led to a wide range of the predicted condensate recoveries over a typical life time of a shale gas producer.
The knowledge gained from this research may provide valuable insight into the optimal fracturing design, including selection of fracture spacing and screening available technology to create the necessary fracture geometry in order to maximize condensate recovery from a rich gas condensate shale field.
Ammonia-Based ASP Processes for Gypsum-Containing Reservoirs
Authors: Sharma Himanshu , Weerasooriya Upali , Pope Gary A. , Mohanty Kishore K. 
Published: October 2014

Abstract
In alkali surfactant polymer (ASP) floods, alkali reduces surfactant adsorption and forms in situ surfactant with active oils, thus reducing synthetic surfactant requirement. Many reservoirs, especially carbonates, contain gypsum or anhydrite. In such cases, a conventional alkali like sodium carbonate cannot be used in ASP formulations because it precipitates as calcite. However, it was found that the calcium concentration in the presence of gypsum can be as high as 2000 ppm without causing any precipitation when ammonia is used as the alkali.Ultralow IFT surfactant formulations were obtained in the presence of up to 1200 ppm Ca2+. Propagation of high pH, good oil recovery and low surfactant retention were observed in an ASP coreflood performed in a carbonate core containing gypsum. The Phreeqc geochemical simulator was used for reactive transport modeling and was found to be an effective tool for designing these corefloods. A good match was observed between the measured concentration of the effluent ions from a coreflood experiment and the Phreeqc simulations.
Application of Fuzzy Set Theory and Expert Judgement in Reliability Analysis of the Arctic Oil and Gas Facilities
Authors: Naseri Masoud , Barabady Javad 
Published: October 2014

Abstract
Reliability analysis has various applications in oil and gas processing facilities such as identifying the bottlenecks of the system, quantitative risk assessments, improving system availability and throughput capacity, and optimising maintenance strategies. Reliability performance of a system can be described as a function of operation time and a series of operational conditions. For this purpose, a range of reliability data is required, based on which the reliability function can be modelled. One of the challenges in reliability analysis of Arctic oil and gas facilities is lack of adequate reliability data. The available historical reliability data gathered in normal climate regions may not be appropriate, as they do not include the effects of harsh Arctic operational conditions on system performance.
In this study, expert judgement process is used to modify the mean-time-between-failure (MTBF) of the equipment to include the adverse impacts of Arctic climatic conditions on system performance. Additionally, fuzzy set theory is used to cope with the uncertainties of experts' opinions in both the component- and system-level analyses. For this purpose, a methodology is presented to perform a fuzzy fault tree analysis (FTA) for system reliability assessments. This methodology is further illustrated by a case study. Based on the results of this study, operational conditions can have various adverse effects on the performance of different components. Additionally, expert judgement can be used as an effective method for system reliability analysis, particularly in the design phase where historical data is scarce.
Elastic Anisotropy of Unconventional Shale at Reservoir Conditions - New, Faster Laboratory Characterization Technique
Authors: Jin Guodong , Pérez Héctor González , Agrawal Gaurav , Ali Abdulwahab Zaki , Khodja Mohamed R. 
Published: October 2014

Abstract
Most unconventional shale formations are transversely isotropic with a vertical axis of symmetry. To fully characterize the elastic anisotropy of a transversely isotropic rock, five independent elastic constants are required. In the laboratory, this tranditionally translates to measuring the wave velocities on at least three separate adjacent core plugs with various orientations - one parallel, one perpendicular, and one at 45° to the bedding. However, it is difficult to drill multiple adjacent core plugs with good quality from a whole core of gas shale because of its weakness and brittleness.
This paper presents a simpler, alternative technical lab procedure of characterizing the elastic anisotropy of transversely isotropic rocks from one horizontal core plug only. The plug is cut parallel to the bedding of the whole core. In the test, it is jacketed in a core holder specifically designed to simultaneously measure six wave velocities at each pressure step: axial compressional, two axial shear, radial compressional and two radial shear. By adjusting the relative position of the sample bedding to the radial velocity transducers, variations of wave velocities with angles is determined; thereafter, the five elastic constants and three Thomsen parameters are calculated. For validation, one synthetic rock sample was constructed comprising thin layers of various materials. Three plugs were cut adjacently from the artificial rock in various orientations: one parallel, one perpendicular, and one at 45° to the bedding. The ultrasonic velocity measurements showed that elastic constants derived from the horizontal plug match very well with those from three plugs, confirming that only one horizontal core plug is necessary to analyze the elastic anisotropy of the transversely isotropic media.
The method's feasibility and applicability was demonstrated by performing the elastic anisotropy analysis at room temperature and various confining pressures on two real rock samples: one tight sand plug and one unconventional shale plug. Both plugs are cut horizontally and exhibit characteristics of layers/beddings or a horizontal zone filled with different minerals. For the tight sand plug, wave velocities measured along the axial direction are in good agreement with those from the radial direction. However, the similar phenomenon was not observed for the shale plug. We analyzed the discrepancy using the micro-CT imaging technique. The three-dimensional geometrical structure of the plug was obtained, and the difference was found to be caused by the non-parallelism of the zone to the symmetry axis of the plug.
Fracture Aperture Calculations From Wireline and Logging While Drilling Imaging Tools
Authors: Maeso Carlos , Ponziani Michel , Le Nir Isabelle , Kherroubi Josselin , Quesada Daniel , Dubourg Isabelle , Luthi Stefan , Slob Evert , Fisher Kelvin , Honeyman Les , Brown Randy , Zenned Olfa 
Published: October 2014

Abstract
The presence of fractures in reservoirs can have a large impact on short and long term production. Electrical imaging tools have a long history in the identification and quantification of fractures in boreholes drilled with water base muds. These tools are particularly sensitive to conductive fractures. The width (also known as aperture) of open fractures is calculated by a well-established equation, relating the fracture width to the excess current measured by the imaging tool (Luthi and Souhaité, 1990). Both mud resistivity and background resistivity of the formation need to be known or measured. The equation was derived from 3-D finite element modeling of the borehole imaging tools of the time.
Recent work has revisited the fracture aperture calculations. The work has verified the approach for electrical imaging from modern wireline tools and extended the principle to Logging While Drilling (LWD) tools. A twofold approach has been taken for the work. Firstly 3-D finite element modeling had been carried out. This includes detailed modeling of the tool sensors' geometry and the analysis of the electromagnetic responses when the sensors are passed in front of a range of fracture widths. The modeling is complemented by a series of physical experiments carried out at Delft University. Setups utilized either a wireline pad or an LWD sensor from the relevant imaging tools. The sensors were traversed across two blocks separated by a precisely measured gap. Measured excess current relates to the fracture apertures and verifies the theoretical modeling work. This combined work confirms the equation for the fracture aperture calculation. In addition the coefficients for both the modern wireline and LWD electrical imaging tools are determined.
Workflows for the quantification of conductive fractures identified on borehole images have been refined and implemented. Fractures are commonly not continuous across the borehole. The workflow includes a fast automatic extraction of both discontinuous and continuous fracture segments. Fractures are grouped into sets based on relevant criteria (such as orientation). Apertures are calculated using the relevant tool coefficients. The fracture density and porosity are then accurately computed along the well. This enables quantification and characterization of the fracture network, including a fast and easy recognition of intervals with specific aperture or porosity ranges. The workflow is demonstrated by examples.
Myanmar’s Taninthayi Nature Reserve Project (TNRP)
Authors: Htay Tharaphi , Htun Linn Thura 
Published: October 2014

Abstract
Tanintharyi Nature Reserve Project, also known as TNRP is the first collaborative project between Ministry of Environmental Conservation and Forestry, Union of Myanmar and our company PETRONAS together with Total E&P Myanmar since 2004. The TNRP encompasses an area of 1,700sq km and is located in the Taninthayi Region in Dawei District, southern Myanmar. TNRP is a long term project that contributes to Myanmar’s Forest Policy of establishing a 5 per cent protection area of the total country area.The objective of TNRP is not only to help develop protection and sustainable management of significant ecosystems and endangered wildlife system but also take into consideration of improvement of the livelihood of local communities.
The project has recorded several milestones: Nature reserve baseline data collection, Flora survey, Fauna survey and Bird survey. At TNRP, conservation of shifting cultivation had been controlled by development of the community Forestry program. It also developed detailed zoning for effective conservation of reserve; core zone, village use zone, integrated buffer zone and transportation corridor.
Environmental Education programme were conducted at schools, the communities and local authority. Seedling and tree planting program which featured a distribution of seedling and annual tree planting activities during monsoon season around TNR was established. Seedlings were distributed to villagers for free and planted at abandoned area of shifting cultivation.TNRP supports the community through agro-forestry by providing with seedlings and micro-finance programme.
As resulted, comparison of satellite scenes indicated that deforestation and degradation rates were decreasing for the two period 1990-2006 and 2006-2010; 0.008% to 0.001% for deforestation and 0.021% to 0.014% for degradation respectively.
Potential for Harnessing the Heat from a Mature High-Pressure-High-Temperature Oil Field in Italy
Authors: Alimonti Claudio , Falcone Gioia , Liu Xiaolei 
Published: October 2014

Abstract
Significant volumes of water are co-produced with oil and gas in mature hydrocarbon developments. Often, the produced fluids are at high temperatures, and cooling is therefore required. However, because of the large volumes involved, one might consider exploiting the co-produced water's geothermal potential in order to reduce both the field's OPEX and the fossil energy needed to continue extracting the hydrocarbons, and so extend the life of the field by delaying its economic cut-off point. Also, there is scope for eliminating the field abandonment costs for the oil and gas operator, who could hand over the field to a geothermal operator when hydrocarbon production became uneconomic; the geothermal operator would in turn save the initial cost of having to drill and complete wells and install surface facilities.
This paper consists of a preliminary assessment of the potential for geothermal exploitation of the co-produced water from wells in the Villafortuna–Trecate oil field in Italy, which has an aquifer that not only provides pressure support to the reservoir, but also represents an in-situ hydrothermal resource, without the need for external water recirculation.
The study compares three different implementation scenarios for the possible use of the co-produced hot water: direct use in district heating, electric power generation through an Organic Rankine Cycle (ORC) plant, and co-generation of heat and power.
The results suggest that, for the power generation option, a single well draining a cylindrical reservoir drainage area could recover approximately 25 GWh of electric power over a 10 year period with an installed capacity of 500 kW. With the co-generation option, which appeared to be the most appealing, a lower net electrical power of 143 kW per well could be obtained, but at the same time approximately 46 utilities could be served by a 660 kW district heating plant per well.
There remain potential permit and licensing issues associated to the concept of harnessing thermal energy from oil and gas developments, depending on the specific country and legal process. For example, it is often the case that the terms and conditions associated with a geothermal exploitation lease are quite different from a hydrocarbon lease.
A Thorough Investigation of Clean-up Efficiency of Hydraulic Fractured Wells Using Statistical Approaches
Authors: Jamiolahmady M. , Alajmi E. , Nasriani H. R , Ghahri P. , Pichestapong K. 
Published: October 2014

Abstract
Hydraulic fracturing is considered as one of the most effective stimulation techniques to improve recovery especially from unconventional low permeability reservoirs. However this promising stimulation technique sometimes does not respond as expected. Significant amount of work has been dedicated to this topic with ineffective fracturing fluid (FF) clean-up considered as one of the main reasons for this underperformance. However there are still great deals of uncertainties in this area primarily due to large number of parameters affecting FF invasion and its back flow.
This work presents results of 10 different sets of numerical simulations consisting of injection, soaking and production periods for 40960 runs. Each set consists of 4096 runs and investigates the simultaneous impact of 12 pertinent parameters (fracture permeability, matrix permeability (km), end points and exponents of Corey gas and FF relative permeability curves in both matrix and fracture and matrix capillary pressure (Pcm) (depending on interfacial tension (IFT), km and pore size index). Two-level full factorial experimental design and linear response surface statistical approaches were used to sample the variables domain, covering a wide practical range determined with the support of our 11 industrial sponsors, and generate output response.
Results indicate that improvement in FF mobility inside the fracture is the major factor affecting FF cleanup efficiency. In line with this finding, maintaining high Pcm, by retaining high IFT, results in cleaner fracture (lower gas production loss, GPL). That is, increasing IFT retains FF within the matrix and allows more gas to flow freely inside the fracture. This was confirmed by the corresponding saturation map of FF distribution. The effect of Pcm was more pronounced when drawdown was very low and/or soaking time was extended. At very low drawdown and when km was reduced, in a set within its variation range, the effect of the resultant increase of Pcm on GPL was more pronounced than that of the resultant decrease in FF mobility. Generally when injected FF volume increased, larger GPL was observed and reduction of GPL (cleanup) was also slower. As fracture length decreased, cleanup was faster and the effect of fracture pertinent parameters on GPL, compared to those of matrix, decreased.
This works findings allows better evaluation of benefits of this costly operation leading to an optimized design and more efficient ways to improve its performance. For instance, sometimes aiming for a longer fracture, due to its FF poor cleanup performance, is not practically attractive and use of IFT reducing agents to produce more FF during the back flow period, would not have the intended impact to bring back its performance to the desired ideal level.
Expedited Country Startup with a Large Scale Mobilization of CO2 And H2S Equipment and Services for a Major Oil and Gas Company in Latin America
Authors: Daher Elie , Shah Babar , MacDonald Steve , Almeida Daniel 
Published: October 2014

Abstract
The process of establishing a company and operating facilities within Brazil to support a large-scale operation, along with mobilizing 10 offshore packages of CO2 and H2S protection equipment and developing safety professionals, within a tight time frame of 90 days, is a significant challenge. Brazil regulations are unique and distinct, thus requiring much work in establishing a local company with an approved operating facility. The processing periods for attaining document approvals added to time restraint challenges.
The assembly, shipping and importation of the safety equipment had to be managed simultaneously. To ensure that equipment were in compliance with in-country local requirements, a thorough understanding of the rules and regulations was necessary to minimize delays during shipping and importation. Requirements for personnel dictated that a local content had to be in place. Thus, local human resource policies in recruiting, remuneration, development, and termination needed to be understood.
In order to tackle these challenges, a Brazil Task Force composed of multi-cultural senior executives was formed leveraging the support services and field personnel from all corners of the world. Initially, the Brazil Task Force conducted a country needs assessment to identify all the requirements, and to get ‘on the ground’ feel for the business environment. Subsequent to their return, they formulated a strategic implementation plan.
A considerable financial commitment was poured to establish a solid, reliable infrastructure within Brazil, and to procure the required specialized equipment and personnel. A local entity was promptly established in Rio de Janeiro to handle all the legal and financial requirements. The company engaged consultants from several specialized fields to leverage local knowledge and experience. They provided crucial advice on startup of operations specifically on the process of obtaining licenses and permits as well setting up contracts with required local suppliers.
The required safety equipment was assembled leveraging its outstanding manufacturer relations for the prompt delivery of the large volume of equipment for this project. The equipment were documented and packaged efficiently to allow for ease of transport and understanding at customs clearance.
This paper takes a detailed look at the various challenges faced, lessons learned and the key factors that contributed to this project's resounding success.
"LULA" Large Scale Oil Spill Response Exercise: a Unique Opportunity to Test a Full Set of Spilled Oil Monitoring and Modeling Techniques
Authors: Michel C. , Cazes L. , Eygun C. , Page-Jones L. , Huet JY. 
Published: October 2014

Abstract
TOTAL E&P Angola organized, from the 13th to the 15th of November 2013, a large scale oil spill response exercise, called "LULA". The oil spill strategy for the response to a 50 000 bopd blow-out scenario in deep offshore Angola was implemented. Offshore resources were actually deployed and tested, including subsea response with a newly developed subsea dispersant injection system mobilized from Norway and operated from a newly designed and built Light Well Intervention Vessel, and surface response (dispersion, containment and recovery). The implementation of an onshore response plan, encompassing shoreline protection and clean-up, waste management and oiled wildlife response, was simulated. This exercise provided a unique opportunity to mobilize simultaneously a wide array of oil slick monitoring techniques at sea. The assessment of their domains of application and effectiveness was made possible thanks to a special permission given by the Angolan authorities to release a limited amount of crude oil at sea surface.
Daily monitoring was implemented to assess the drift and behavior of the spilled oil and to guide resources during the response operations. Several technologies were tested. Drifting buoys were launched to reflect the oil slick position in near real-time by satellite transmission. Aerial surveillance was carried out by helicopter and by fixed-wings OSRL aircraft (mobilized from Ghana) to provide detailed information about the oil slick (position, shape and location of thickest slicks). These techniques were complemented by one of the latest innovation of the TOTAL Group: the observation balloon BOOST. This balloon, fixed to a supply vessel, provides an overview of the slick from 150 m altitude through a camera which feeds back visible and infrared geo-localized images, thus enabling positioning the response vessels on the thickest parts of the slick and initiating response at first daylight. RADAR imagery was also collected by satellite. A set of techniques enabling 5 days oil spill drift predictions is combined in another Company innovation: SPILLWATCH service, which includes 3D currents and winds forecasts, oil subsea/surface behavior and slick drift modeling, and daily recalibration using the RADAR images.
The results obtained during LULA demonstrated the consistency of the various techniques and confirmed the possibility to track a slick during day and night time.
Being able to follow spilled oil at sea is part of the Company's responsibilities. These tests onsite will considerably improve our good practices and should benefit to the whole Oil & Gas Industry.