A Well with plug set in both tubing was sabotaged and even after initially capping the well, it was observed that attempting to kill the Target Well via surface pumping was abortive. Therefore, in order to achieve well control, drilling a relief well became imperative and required some critical decision to be taken. This include location selection, type fluid to be used in drilling, the casing setting depth, downhole measuring tools for use, as well as contractors needed in achieving success in a suitation of incomplete well survey data. This paper presents how this keys needs were met in drilling the Relief Well planned for 97days trouble free and performed in 107days from spud to hitting Target Well. The success was on single attempt in spite of it having an incomplete survey record acquired 49 years earlier.

A producing well located offshore Congo was equipped with a TRSCSSV which failed to open. A velocity valve, with a stem beneath, had been installed to keep the flapper open. This condition, apart from restricting the production, was a temporary solution as defined in Eni's (the operator) well integrity policy; for this reason, the SSV had to be replaced. In order to do so, the completion needed to be removed, which implied cutting the cut-to-release packer. A lock open tool needed to be run in the SSV to allow the cutter to reach the packer. The lock open tool was too big to pass the tubing hanger. Eni issued a challenge to the service industry, to come up with a solution to enlarge the hardened tubing hanger while preserving its mechanical integrity. The solution also had to be deployable quickly as the drilling unit could incur costly standby. The retained solution used a wireline deployed milling toolstring equipped with a diamond coated bit. The benefits of this solution impacted several areas: the surface read out system allowed for fine control of the milling operation, the combinability of the tools allowed for adequate planning of potential fish recovery while retaining well barriers on a live well and the size of the equipment allowed for a rapid overseas mobilization. The milling operation was completed in a single run, with a total milling time of 1hr 47min. The paper will discuss the project scope of work, equipment preparation and job execution, an estimate of the risk and cost reduction delivered, and an estimate of the added production enabled by removing the failed SSV.

The composite liner is made of a Glassfibre Reinforced Epoxy (GRE) resin, inserted in Carbon Steel tubing and it can be used in both production and water injection wells. Different laboratory tests performed either by manufacturers and by operators, have been carried out in order to confirm and verify the material characteristics and reliability. In particular, Eni in 2009 tested GRE in sour environment with CO2 and H2S to investigate the capability and service limits of the resin liner at different temperatures. According to the positive results of the tests, Eni has firstly applied GRE in 2005 in Tunisia where it was successful in reducing onshore workover costs and extending the life of Carbon Steel tubing in oil producer wells with high CO2 and water cut. The latest application was in Norway where it has been installed on water injector offshore wells, where, due to high corrosiveness of the injection fluid (raw seawater with antifouling chlorination), the liner was selected as cost effective alternative to high alloyed materials. More recently, Eni was involved in particularly challenging deepwater development projects with highly productive gas wells in sour and harsh environment. Typically, these applications require high grade Corrosion Resistant Alloys (CRA) production tubing with an important impact on the completion costs and operative run in hole issues. Following the positive experiences gained in the last 15 years in the application of glassfibre liner, it was evaluated the possibility to deploy the material as a corrosion barrier in well production tubings under more critical conditions. Eni decided to perform some additional laboratory tests in collaboration with Milan Polytechnic. Direct impact test and straight pipe test were performed in order to characterize the erosion behaviour of GRE composite material, supplied by two different manufacturers, and simulating the case of wells with high erosion rate risk. The results demonstrated GRE to have a good resistance to the solid particles erosion in comparison to very similar tests on Inconel Nickel Alloy material and confirmed the potential use of GRE as a corrosion resistance material when combined with Carbon Steel tubulars as an alternative to the usual high CRA materials in producer wells. This paper will present the characteristics of the technology, the laboratory tests performed with their results and the acceptable range of field conditions. Additionally, the paper will provide Eni field experiences, including feedback, lessons learned and economic evaluations.

Way of working is continuously changing in O&G field thanks to digital solutions and the possibility to have consistent data driven analysis to support decision-making process. Well Construction cycle from planning to execution and post well analysis is evolving as well, since data are at the base of all the analyses allowing higher operational safety, more efficient engineering, better real time optimization and more effective comparison of performances at the end of operations. Eni Well Operations Department has invested a lot in advanced analytics tools able to extract value from historical and real time data focusing the attention first of all on data coverage, quality and reliability, that are extremely important enablers to let the tools work and perform analyses, and then on proper data transmission system from different rig site locations towards a centralized database. High frequency performance measurement and data intelligence tools allow reaching the technical limit, predictive analytics help in reducing downtime while drilling and well simulation software enhances not only planning phase but also operational real time follow up activities. Applications of digital solutions have run in 2019 on most challenging activities with tangible results in terms of safety improvement, operational efficiency and time and cost savings. Almost 50 wells (more than the totality of most complex wells as per Eni classification) have been analysed in real time with both advanced analytics and predictive algorithms achieving: avoidance of specific Non Productive Time events (about 25% of NPT reduction), with a major impact on operational safetybetter performances throughout development projects, thanks to an improved learning curve and a reduction of Invisible Lost Time (average of 2,5% of time saving per well)enhanced real time monitoring and early detection of well events, leading to a faster decision making and adoption of corrective actions (anticipated actions by average 6 hours) The development and the application of these tools have been made possible thanks to a proper Data Management System. In fact, several initiatives have been put in place to provide proper data gathering, data transmission, data quality check and assurance and data storage. This paper will show in details how the results have been obtained starting from creating an appropriate data infrastructure up to real case of application along 2019 Eni drilling activity. The extensive use of digital tools, both in Geographical Units and Headquarters, has been proven to provide effective support to plan, monitor and evaluate performances during all well operation activities.

A 1575m [4922-ft] offshore horizontal 4-½-in. liner cemented using a mud-sealing cement system (MSCS) resulted in an outstanding cement bond log result. The decision to use the MSCS was taken after realizing that four offset liners, previously cemented using conventional cement systems, did not yield acceptable cement bond log results despite following oil and gas cementing industry best practices, including pipe rotation. This paper documents a comparison of six offset horizontal liners, focusing on the impact of the MSCS technology. The paper focuses on several 4-½-in. liners in the same field. The wells were drilled by a similar rig and had similar well profiles. The drilling bit, directional drilling tool, drilling fluids system, logging tool, centralizer type and pumping sequences were comparable across all wells. In addition, the logging company performing the cement bond log evaluation was not the same company performing the cementing service. After the first MSCS-cemented well, the subsequent well used a conventional cement system to isolate the 4-½-in. liner and tighten the cementing best practices. This was initiated to irrefutably confirm the impact of MSCS technology on the quality of cement bond log recorded on the earlier well. The cement bond log recorded from the well isolated with MSCS is easily identified among the six comparison wells even though the cementing operation faced several well challenges, includinga single dart liner system implementation (for all liners), which can promote the intermixing of slurry with fluid ahead while travelling down the pipemud losses in the drilling phase, which resulted in a reduction of the displacement rate to control ECD during cement placement. The bond log results of the other wells were qualified as poor or fair, even though significant precautions were taken to optimize zonal isolation. These efforts included batch mixing the spacer and slurry, using more than one centralizer per casing joint, and implementing pipe rotation during pre-job circulation and job execution when the torque limit allowed. This multi-well comparison based on field results brings solid evidence of the MSCS technology interacting with the residual layer of nonaqueous fluid (NAF) when well conditions reach or exceed the practical normative limitations for mud removal. This in-situ interaction generates a viscous paste that positively impacts the bond log response and bolsters the isolation between zones of interest. The result has yielded a step forward in the provision of a dedicated barrier technology for horizontal or highly deviated sections.