Lost Circulation Risk Mitigation in Deepwater Cementing Operations with a New Tailored Spacer System

Lost circulation (LC), commonly encountered in drilling and cementing operations, can be a costly problem that increases non-productive time, especially in highly permeable formations. When LC occurs during cementing, zonal isolation can be compromised. Risks associated with LC affect most applications, including offshore operations. This paper presents the evaluation of a new tailored spacer system (TSS) designed to effectively mitigate LC and its use in deepwater cementing operations to meet zonal isolation objectives.

Surveying a Floating Iceberg With the USV SEADRAGON

The calving, drifting, and melting of icebergs has local, regional, and global implications. Besides the impacts to local ecosystems due to changes in seawater salinity and temperature, the freshwater influx and transport can have significant regional effects related to the ocean circulation. The increased influx of freshwater ice due to increase calving from ice shelves and the destabilization of the continental ice sheet will affect sea levels globally. In addition, drifting icebergs pose threats to offshore operations because they could damage offshore installations, e.g., pipelines and subsea manifolds, and interrupt marine transportation. Iceberg drift and deterioration models have been developed to better predict climate change and protect offshore operations. Iceberg shape is one of the most critical parameters in these models, but it is challenging to obtain because of iceberg movement caused by winds, waves, and currents. In this paper, we present an algorithm for iceberg motion estimation and shape reconstruction based on in-situ point cloud measurements. The algorithm is developed based on point cloud matching strategies, policy-based optimization, and Kalman filtering. A down-sampling method is also integrated to reduce the processing time for possible real-time applications. The motion estimation algorithm is applied to a simulated data set and field measurements collected by an Unmanned Surface Vehicle (USV) on a free-floating, translating, and rotating, iceberg. In the field data, the above-water iceberg surface was measured with a scanning LIDAR, while the below-water portion (0–50 m) was profiled using a side-looking multi-beam sonar. When applying the motion estimation algorithm to these two independent point cloud measurements collected by the two sensing modalities, consistent iceberg motion estimates are obtained. The resulting motion estimates are then used to reconstruct the iceberg shape. During the field experiment, additional oceanographic measurements, such as temperature, ocean current, and wind, were collected simultaneously by the USV. We have observed water upwelling and a colder and fresher water plume at the sea surface downstream the iceberg. Combining the iceberg shape rendering and the surrounding environmental measurements, we estimated the iceberg melting parameters due to the sensible heat flux and surface wave erosion at different iceberg sections.

The Impacts of Climate Change on the Windows of Offshore Operations

Ocean renewable energy has a central role to play in decarbonizing the global energy system. The emergence of new technologies such as floating wind farms will significantly increase offshore wind deployment by providing access to large areas of the seabed that are not suitable for fixed bottom turbines. Operations and Maintenance (O&M) is estimated to contribute 50% to an offshore wind farm’s total operational cost. The ability to improve the efficiency of O&M activities will enable offshore wind to compete with traditional fossil-based and onshore-renewable generation methods. To achieve this, an accurate characterization of the metocean environment is a mechanism of reducing delays and costs across the entire project lifecycle. One of the most significant costs associated with offshore operations is accessing a site with vessels. Site access is determined using vessels constraints in the maximum allowable meteorological and ocean (metocean) conditions and is defined as weather window analysis. However, industry guidelines and standards rely on historical data and do not consider the impact of climate change on the marine climate and the associated vessel operability. This requires the use of climate projection data. The opportunity to use an existing industry metric such as weather windows will tailor the climate projection data to the end-users needs. This paper’s findings suggest that climate change will alter the metocean environment and vessel operability for the case study location investigated. The findings demonstrate the value of site-specific assessment of the future wave climate to inform operational decision making. The main conclusion is that longer-term planning will require the offshore wind sector to consider the impact of climate change on O&M activities.

An assessment of the feasibility of using skirt containment boom together with paravanes for offshore response

The use of conventional offshore containment boom is a recognised way of containing and recovering oil spilt at sea. However, there are various operational and logistical challenges with their use. One of the largest being that their containment becomes ineffective when towed through the water at speeds of greater than 0.75 knots. Containment and collection of oil using high speed systems allows for greater tow speeds (2–3 knots) without failure and can be operated with a paravane as a single ship system. Oil Spill Response Limited (OSRL) have had numerous requests from its members to supply offshore containment and recovery systems suitable for a single vessel deployment. The reason for this was to help with the challenges of low availability of vessels suitable for offshore operations and to reduce high costs. OSRL have used manufacturers guidance to advise its members on the best options however wished to have its own data to further support this guidance and provide user-validated recommendations to its members. OSRL have investigated the viability of using a paravane with a conventional offshore boom using field tests. These tests focused on vessel tow speed, current speed, boom containment effectiveness and encounter area. A number of deployments were carried out using conventional inflation boom and a medium sized paravane in Southampton Water, UK in 2018 (Figure 1). Observations were gathered to identify the point of boom failure when towed at different speeds and whether a suitable encounter area could be achieved. This poster will provide the detail on the feasibility of towing a conventional offshore boom with a single vessel and paravane, see boom configuration in Figure 2. It will outline specifications and parameters which make for a successful / unsuccessful deployment of conventional boom with paravane and provide recommendations for Tier 1 single vessel deployment equipment.

Project Management Strategy: Managing Covid-19 Global Pandemic for Deepwater Offshore Operations in Remote Location

During the declaration of COVID-19 as a global pandemic by World Health Organization (WHO), the work of plug & abandonment of 15 deepwater subsea wells were ongoing in Field "C". Discovered in 2001, the field is located approximately 80 km west of coastline and about 90 km from Nouakchott, capital of Mauritania, situated in West Africa. Field "C" is a deepwater field in water depth ranging from 730m to 830m. The field was developed using subsea wells, Hinged Over Subsea Templates (HOST), manifolds, flexible flowlines, umbilicals and risers tied back to a permanently moored FPSO. The field consists of nine (9) oil producer wells and five (5) water injection wells. During the development stage, one (1) gas injection well was drilled and completed at adjacent Field "B" about 17 km Northeast of Field "C". The water depth at this gas injection well location is approximately 280m. The diagram below shows the Field "C" and Field "B" layout. Field "C" has reached maturity in 2016. Due to high operating costs, declining production coupled with declining oil prices, the decision was made to cease production, plug and abandon (P&A) and decommission the field. Two phases strategy was engaged by the Operator in order to complete the decommissioning and abandonment of Field "C". In Phase 1, which was executed back in the year of 2017-2018, all the 15 deepwater subsea wells were temporarily suspended with two (2) barriers in place. The Floating, Production, Storage and Offloading (FPSO) unit was decommissioned and disconnected. In line with the strategy of dividing the project into two phases, the information on well integrity and conditions acquired during the Phase 1 Temporary Wells Suspension (TWS) was used by the Operator in planning for Phase 2 – Wells Plug and Abandonment (P&A). The Operator made full use of the temporary well suspension period between Phase 1 and Phase 2 for engineering, procurement and operations preparation. The same drillship was utilized for the project in both phases. Multiple optimizations and modifications were done on the drillship based on lessons learned in Phase 1 and to cater for the subsea Xmas Tree and subsea structures retrieval in Phase 2. Due to the nature of the remote location and no existing oil & gas operations support base, all equipment required in this project was sent to Mauritania early. Equipment inspection and acceptance were carried out in Mauritania as part of the strategy in ensuring the availability of good quality equipment for offshore operations. The operations on Wells Plug & Abandonment commenced in December 2019. In March 2020, upon declaration of the COVID-19 pandemic, the Operator was faced with the difficulty of continuing operation as the Host Country activated border lockdown. The Operator managed to continue operations for remaining well and demobilized drillship and personnel safely. The Operator has successfully retrieved three (3) subsea Xmas Trees, P&A three (3) wells and intervened six (6) other wells for tubing cutting before operations was suspended due to COVID-19 pandemic. The Operator used the suspension phase to devise a methodology to resume operation in the prevailing COVID-19 pandemic situation. The challenges faced during the COVID-19 pandemic as well as the steps taken for resumption are highlighted in this paper.