Selecting a Coiled Tubing Unit for CTD: Part Two
Following on from , this article continues to explore the areas required to select a suitable CT unit for Coiled Tubing Drilling operations.
Price & Performance
Price is the obvious one! However, the cost is never the only consideration and care should be taken to review the CTU provider’s performance history. Furthermore, you should look at their accident and incident records and their safety culture. CTD should always be considered as a technology that offers a high return on investment but this does not necessarily mean the lowest upfront cost.
A CTU provider may choose to charge in a number of ways. This could include a basic day rate with itemised charges for elements such as coil fatigue, mobilisation for example. Both the Operator and the CTU provider should be fully aware of exactly how the CT is going to be used i.e. the unique drilling practices associated with CTD.
Pressure Control Equipment (PCE)
Careful consideration must be given to the PCE and its pressure rating. A CTU provider may work on wells under a variety of pressures and so should have a selection of BOP stacks and other PCE available. The PCE must be selected in accordance with the expected well pressures and operations. All potential well control scenarios should be considered in a risk assessment along with the selected PCE.
The quantity of data that it is possible to capture from a CTD project is vast. Serious consideration needs to be given to what information you would like to capture and how this can be achieved with the chosen CTU provider. Your CTD BHA provider should be able to provide the requested data acquisition services for all the services onsite if required. Choosing a CTU that has advanced data acquisition and transmission systems will facilitate displaying data to the interested parties whether you use the BHA provider as a hub or the CTU provider.
The operations that are carried out before and after drilling an open-hole section with coiled tubing can have extremely significant cost impacts. If there is a requirement to pull completion tubing before drilling and/or to run completion tubulars after drilling, then a workover unit may need to be used. This inevitably adds extra mobilisation costs and rig up/down time. The most effective way to carry out operations on wells like this is to utilise a hybrid CT unit. Whilst these units are capable of running pipe as well as coiled tubing, they are quite rare. However, if utilised, they can have significant, positive impacts on the economics of the well.
Author: Adam Miszewski