Coiled Tubing (CT) technique is mostly considered for drilling or well intervention operation rather than an effective completion tool. This paper aims to demonstrate, using examples carried out in Italy and in West Africa, that this technique is a surprisingly effective means for marginal field exploitation and mature fields rigenaration.
The term "marginal field" was introduced to identify fields where the economics for development are critical. More specifically it is possible to define a marginal field as a field that is uneconomical to develop with conventional drilling and completion technology.
The marginality of a field can be due to any of the following reasons or a combination thereof: small reserves, remote location, deep water, strict environmental limitations, heavy oil. More than eighty marginal onshore sweet shallow gas prospects were identified in the Po Valley, Northern Italy, with reserves of less than 300 million of m3 at 1500 - 2500 m TVD and with expected production per string ranging from 30,000 to 70,000 m3/d, water cut is possible whilst sand production, temperature and pressure are not considered to be prominent problems, which could not be developed economically using conventional rig and completion design.
The employment of a CT Completion technique may enhance the economics of marginal prospects and / or constitute a valid option for mature field interventions.
The application of the CT technique is constantly growing and oil companies have begun to employ CT for drilling and completion purposes.
The eye catching advantage of using a continuous, as opposed to a jointed string is the elimination of the need to make up or break out connections thereby considerably reducing tripping times.
A CT Unit has a smaller footprint than a conventional rig and a small foot print rig (see table below) and this can be an advantage where the footprint needs to be minimised.
Furthermore, the mob/de-mob times are considerably less for a CT Unit compared to a Conventional and Small foot print Rig.
For CT Unit only 4 trucks are required: 1 for CT. Reel and Control Cabin, 1 for pump and mixing tank, 1 for a small water rig used just for suspend CT Injector and 1 for Wire. Line equipment