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Onaisi A.,Total S.A. | Fiore J.,Total S.A. | Rodriguez-Herrera A.,Schlumberger | Koutsabeloulis N.,Schlumberger | Selva F.,Total E and P Angola
49th US Rock Mechanics / Geomechanics Symposium 2015 | Year: 2015

Subsurface pressure and temperature variations can alter rock properties both near and relatively far from the disturbance, causing detectable changes in seismic travel times. In modelling such phenomena, we employ large-scale geomechanical simulations to translate reservoir depletion values into rock deformations accounting for overburden heterogeneity and heavy faulting patterns derived from seismic interpretation. Subsequent velocity perturbations are then obtained using strain-dependent stiffness perturbations from nonlinear elasticity theory. By applying this methodology to a channelized turbidite reservoir located in offshore West Africa, we show that appropriate calibrations can generate geomechanically-derived overburden time-shift predictions that reproduce signatures from an actual 4D seismic monitor survey, providing valuable insights into reservoir pressures, rock compressibility and fault stiffness. The results also demonstrate the importance of integrating non-homogeneous overburden descriptions in successfully explaining many 4D seismic signatures. Copyright 2015 ARMA, American Rock Mechanics Association.

Toinet S.,Total E and P Angola | Maultzsch S.,Total S.A. | Souvannavong V.,Veritas Software | Colnard O.,Veritas Software
First Break | Year: 2011

We have run a 4D pre-stack inversion on seismic data acquired over a giant field located in deep water offshore Angola. The objective was to obtain dynamic information from 4D seismic data. The 4D inversion workflow started with a prestack 3D inversion of the baseline seismic survey. Using the relative P-wave velocity variations computed by warping, the initial impedance model of the baseline was updated in order to build the initial impedance model for the monitor survey. The update was done through a 4D mask which defines where impedance variations are allowed between the baseline and monitor impedance volumes. Due to the poor impedance discrimination between shales and water-bearing sands, where 4D effects may occur because of salinity differences between injected and aquifer water, reservoir model information was introduced in the mask in order to locate water-bearing sands. Ranges of relative impedance variations computed by the inversion were limited by 4D constraints derived from reservoir simulations before first oil and at the time of the monitor survey. 4D inversion brought sharper images compared to other 4D attributes. The high quality of the 4D inversion results evidenced by quantitative quality controls has opened the way to quantitative applications in reservoir management. © EAGE.

Masse P.,Total E and P Angola | Laurent O.,Total S.A.
Comptes Rendus - Geoscience | Year: 2016

This paper provides a review of the Geological exploration of the Angola Coast (from Sumbe to Namibe) from pioneer's first geological descriptions and mining inventory to the most recent publications supported by the oil industry. We focus our attention on the following periods: 1875-1890 (Paul Choffat's work, mainly), 1910-1949 (first maps at country scale), 1949-1974 (detailed mapping of the Kwanza-Namibe coastal series), 1975-2000, with the editing of the last version of the Angola geological map at 1:1 million scale and the progressive completion of previous works. Since 2000, there is a renewal in geological fieldwork publications on the area mainly due to the work of university teams. This review paper thus stands at the frontier between geology, natural resources and the history of geology. It shows how geological knowledge has progressed in time, fueled by economic and scientific reasons. © 2015 Académie des sciences.

Deplante C.,Total e and P Angola | Jeanjean F.,Total e and P Angola | Sebastiao V.,Total e and P Angola | Sageder S.,Total S.A.
76th EAGE Conference and Exhibition 2014, Workshops | Year: 2014

On a turbiditic deep offshore field covered by a recent yet conventional 4D baseline, a non-conventional route has been decided for the first monitor, to obtain seismic information related to dynamic heterogeneities but also better characterize reservoirs. The strategy decided for the first monitor (Ml), one year after first oil, was to shoot broadband and process twice:-One 4D-dedicated processing mapped to conventional (with a Fast Track and a Full Processing phase) in order to match the baseline characteristics and obtain quality 4D signal to help understanding the early dynamic behaviour of the field.-One 3D broadband processing aiming to improve the existing seismic for reservoir characterization purposes. The superior resolution of the 4D signal over conventional data helps pushing the interpretation below the 3D resolution limits and has helped identifying sedimentary features which have confirmed the interpretation model but are also difficult to map accurately. Using the 3D broadband processing results, small scale geological details previously guessed from conventional data and locally underlined by 4D signal (but only at places impacted by changes in saturation and pressure), can now be seen more clearly: a more comparable resolution is achieved for 3D and 4D.

Michel C.,Total E and P Angola | Cazes L.,Total E and P Angola | Eygun C.,Total E and P Angola | Page-Jones L.,OTRA | Huet J.Y.,OTRA
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2014

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: SPILL WATCH 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. Copyright © 2014, Society of Petroleum Engineers.

Letki L.P.,WesternGeco | Menari A.,WesternGeco | Zamboni E.,Total E and P Angola | Tchikanha S.,Total E and P Angola
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

A narrow azimuth survey and an overlapping Coil survey were acquired and processed for TOTAL offshore Angola. After fast track processing, a direct comparison showed that at a specific location a subsalt steeply dipping event was better defined on narrow azimuth image than on the Coil image. This case study illustrates how illumination analysis can be used to make critical survey design, acquisition and processing decisions. The initial flower plot analysis helps determine the survey design requirements to illuminate target horizons, and will fully justify the need for a full azimuth design. Then, an acquisition illumination analysis complements the previous analysis by creating offset and azimuth illumination maps for chosen design. This identifies illumination and shadow zones on the target horizon. This can be directly related to the seismic data and used to design an appropriate processing solution. Finally, during the processing phase, the specific azimuth contributions identified from illumination analysis need to be separated into azimuthal images. These are intelligently stacked to create the final image, using an intelligent stacking method, designed to retain azimuth specific contribution. To use the full benefit of Coil Acquisition, this two-steps processing strategy derived from the illumination analysis, is essential. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

Buia M.,ENI S.p.A | Khaled N.,Total E and P Angola | Tchikanha S.,Total E and P Angola | Zamboni E.,Total E and P Angola
Oilfield Review | Year: 2013

The Coil Shooting technique, in which a single vessel acquires full azimuth 3D seismic data by sailing in circles, delivers more-accurate and reliable subsurface images than conventional 3D methods in areas of complex geology. Recently, a multivessel implementation of the technique has been developed to address subsalt imaging challenges in deepwater areas. Copyright © 2013 Schlumberger.

Martins E.,Total E and P Angola | Manuel M.,Total E and P Angola | Merzi T.,Total E and P | Canovas S.,Euro Engineering | Guillou A.,Euro Engineering
Society of Petroleum Engineers - SPE International Conference and Exhibition on Health, Safety, Security, Environment, and Social Responsibility | Year: 2016

The aim of this paper is to present the Affiliate's environmental monitoring strategy and summarize results of indicators to follow up cumulative impacts on deep water environment, between 1998 and 2015, which proved to be rather low or negligible, and acceptable on the long term. Since February 1998, when the first environmental baseline study (EBS) was performed (in Block 17: Girassol) to describe the initial state of the environment, the Affiliate has been conducting regular offshore monitoring campaigns with the aim of characterizing the water column, and marine sediments around existing installations and developing fields. These surveys are not limited to Block 17, but also extend to other Affiliate offshore blocks in Angola. In March 2015, the Affiliate's most demanding Global Environmental Baseline & Monitoring Survey (GEMS) was completed, which covered six different offshore blocks, with a work scope ranging between EBS and EMoS (environmental monitoring survey), comprising 226 sampling stations for sediment and benthic macrofauna, 26 for seawater, 17 for phytoplankton and 8 for foraminifera. Another specificity of this latest GEMS was the scientific vessel that was shared among Operators through a joint agreement, of course with some legal and operational constraints considering the socio-geographic context of the project. Technically, besides the Affiliate's required guidelines and rules, the parameters to be tested also had to meet recent regulations from the Ministry of Petroleum. Physico-chemical and biological data obtained over the past 17 years have been used as indicators of environment quality, and its regular monitoring allows assessment of the sensitivity of the marine environment to petroleum activities. Copyright 2016, Society of Petroleum Engineers.

Frangois B.,TOTAL E and P Angola | Antonio C.,Sonangol
Proceedings of the Annual Offshore Technology Conference | Year: 2015

Local content was fundamental to Total E&P Angola's development philosophy for the CLOV mega- project, offshore Angola. The aim - To allow CLOV to provide with a lasting legacy in terms of human and facilities resources - was to achieve 10 million man-hours of local activity in Angola at first oil - A tenfold increase from Total's first deepwater development at Girassol - And the fabrication of 64,000 tonnes of structures in five domestic construction yards. Based on Total E&P Angola's policy of sustainable development, a plan was devised and executed that included specific health, safety, environmental and quality requirements and ethical standards, all in accordance with Angola's socio-economic and cultural characteristics. Local content challenges were identified at early stage of the project. It allowed the development of a sound strategy based on selection, management and execution. This resulted in the upgrades of three of the five fabrication yards which were implemented in a cost-effective and timely fashion to meet overall project cost and schedules. It was of paramount importance that if these yards were to perform essential work, they had to be manned with a skilled local workforce. Therefore, training was another key area of development for both the project team and contractors. Copyright © (2015) by the Offshore Technology Conference All rights reserved.

Meyer M.,Total E and P Angola
Proceedings of the Annual Offshore Technology Conference | Year: 2015

At early stage of the project, the CLOV project developed an innovative training with the target to certify new junior operators with a diploma (level 2 French Diploma) and hire them as operators for Total E&P Angola. For the first time in an affiliate, CLOV conducted an 18-month training program in Angola divided in 3 steps: An intensive English course (3 months), a scientific refresher course (2 months) and the upstream operators certification (13 months) in cooperation with Institut Francais du Petrole (IFP). This part-time training was divided into 22 weeks of scientific and technical courses and 18 weeks of "on the job training" meaning offshore training onboard FPSO. During all the period, numerous dedicated trainers from IFP and from Total E&P Angola were involved to supervise the trainees and interact with them. At the end of this program, trainees were selected and certified as upstream operators and hired by Total E&P Angola. Then they attended a "specific training" for CLOV. This new phase lasted 5 weeks during which the new operators had theoretical courses on CLOV facilities and hands-on exercises with a 3D tool, the Immersive Training Simulator (ITS). This ITS allowed them to familiarise with CLOV FPSO facilities and process, not yet achieved at that date. Then, the new operators were sent in Korea to participate in the commissioning activities before the FPSO sail away. They continued their training onboard Block 17 FPSOs in Angola during the FPSO tow and came back onboard at the arrival of CLOV FPSO in Angola to prepare the first oil. They are now professional operators for CLOV. This complete training program currently being deployed in Total affiliates will allow graduate operators with a 2 years diploma, to strengthen skills of local workforce and to build a win-win partnership with the country. Copyright © (2015) by the Offshore Technology Conference All rights reserved.

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