Page 53: of Offshore Engineer Magazine (Aug/Sep 2014)

52 54

Liner tieback – The durability of the

Drilling metal-to-metal seal enables the liner tieback to operate at high pressures and temperatures, making it ideal for deepwater challenges.

A system designed to monitor and manage well integrity should at a minimum set out clear standards to ascertain the integrity of the wells under management for their entire life cycle.

This would include safe and continuous functionality aimed at meeting required production targets. In light of past well integrity lapses, some of which have resulted in loss of life and environmen- tal and economic damage, a robust well integrity management system is a require- ment for any operator interested in being a good corporate citizen.

The limitations of existing isolation technology

While technologies, such as infatables, swellables and mechanical packers, have played a key role in securing well integrity and zonal isolation in the past, they do come with limitations.

Swellables in particular are relatively inexpensive and easy to install without compromising casing strength, and yet come with reliability issues relating to the polymer swelling, the size of the diameter changes, structural integrity issues from other fuids, and the time it takes to swell, which can sometimes be up to 30 days. These technologies have integrity – particularly since Macondo – aquifers, for example, protective coatings, an important role to play in isolation, but ne of the biggest issues fac- questions still remain as to well integri- thicker casing and cementing all strings there is a need for other technologies to ing the offshore oil and gas ty’s role in the well’s lifecycle. Questions to surface are just some of the tactics that harness their benefts while overcoming

O sector today is well integrity. include: What exactly is well integrity have been used to combat the attacks on their weaknesses.

This challenge was made apparent by a and when does it start in the well lifecy- the integrity of well bores. The loss of

Metal-to-metal study conducted on a number of wells cle? Is it possible to protect it and at what production inficted on operators by the on the Norwegian Continental Shelf by stage? And how can a safe and effective corrosion of casing strings is indeed sub- Meta has Metalmorphology for this area.

Norway’s Petroleum Safety Authority balance be found between protecting well stantial and in fact is growing every year. Metalmorphology uses established metal (PSA), which found that every ffth well integrity while maximizing production? This can even lead to the loss of the well working principles to shape metal down- analyzed had well integrity weaknesses. and/or damage to the reservoir. Some hole to deliver a gas tight and durable

Robust well integrity

Regulatory requirements, in the North operators have reported well failures metal-to-metal seal.

Sea and Gulf of Mexico in particular, Sadly, many older wells were not in as little as two years from the start of The technology balances the mechani- are increasing the onus on operators to designed for long life, so in some ways production of a well. cal strength of steel with its elastic establish structural integrity and contin- they were destined for early failure from Many operators have carried out a properties to create isolation solutions gencies at the planning stage; recomplete the outset. Well life cycles of 30-50 years detailed risk analysis of their well stock that instantly morph together to provide existing producing wells to comply with are what is needed in many producing in an effort to rank each well from good 100% conformance within the wellbore new legislation; ensure that well integrity felds around the world. These life cycles to bad. This type of risk analysis is only or casing. It provides a morphing ratio up is not compromised by trouble zones and are achievable. Many studies based on as good as the data available for review to 60%, an axial load bearing rating up to stuck casing; and reinstate well integrity statistical data have been conducted and evaluation. Designing a robust, six million lbs, and a sealing rating of up quickly when damage does occur. over the years in an effort to understand database-driven, analytical tool is a to 15,000psi.

Despite the growing importance of well the causes of casing failure and possible frst step in risk ranking of a given well The result is a gas-tight, axial load solutions. This has involved the study of stock. Factors to be part of the database bearing, metal-to-metal sealing solution, large data sets gathered over many years includes well construction types, annu- which meets well integrity legislation as

Metalmorphology is the process of of production. lus pressure, production data and well well as giving operators absolute conf- shaping metal downhole to provide a metal-to-metal, gas-tight seal for the life

For external corrosion of wellbore intervention information just to name a dence in their isolation and well integrity of the well. Photos from Meta.

casing and strings, caused by corrosive few of the parameters to investigate. solutions.

oedigital.com August 2014 | OE 55 054_OE0814_D&C2_Meta.indd 55 7/22/14 6:25 PM