Coiled tubing drilling is an area where geologists and engineers must work together very closely, because an understanding of the formation is absolutely vital when planning wells drilled in tight gas sands, unconventionals, and in re-entries.
New developments in coiled tubing have made it possible to economically drill and produce often overlooked zones and re-entry drilling.
Welcome to an interview with Richard Stevens, an expert in the area of coiled tubing drilling, who discusses the drilling technique and the importance of teams that include engineers and geologists.
1. What is your name and your relationship to the oil and gas industry?
My name is Richard Stevens. I’ve been in the Oil and Gas Industry, at AnTech, since graduating from University in 1997. It’s been my good fortune over the years to get hands on with most of what AnTech does: Designing and manufacturing tools, operating them in the field and writing software to model their performance. I was lucky to be in at the birth of AnTech’s Coiled Tubing Drilling BHA’s, watched them grow from engineering prototypes to field proven tools, then saw them launched as a service package.
2. What is Coiled Tubing Drilling and where is it used?
Directional Coiled Tubing Drilling uses Coiled Tubing to convey a steerable drilling BHA into a wellbore. To date Directional Coiled Tubing Drilling has been extensively used in Alaska, Saudi Arabia and Russia, though mostly confined to high profile, big budget projects.
Because the Coiled Tubing is continuous, there are no joints to make up. This means that steady state pressure conditions can be maintained in the hole while the formation is being drilled. Thanks to the closed circuit nature of the circulation system, we can pump lightened fluids, meaning that the borehole pressure can be maintained lower than the formation pressure. This minimises formation damage while drilling and also eliminates problems of differential sticking and fluid loss associated with conventional drilling. Using AnTech’s instrumented BHA, the difference in pressure can be closely controlled, ensuring that the advantages described above can be delivered without over lightening the wellbore, risking collapse.
Another advantage of the continuous tubing is that tripping speeds can be much higher than conventional pipe. A further advantage of the closed loop circulation system is that dangerous produced gases (Hydrocarbon and H2S) are easier to contain and control.
4. Can it be used in tight sand and shale plays?
Yes it can. Coiled Tubing Drilling provides the precise wellbore pressure control needed for successful tight sand drilling.
In both cases, near balance drilling can be used to minimise filtrate invasion and fluid loss.
Drilling with a small underbalance, and allowing the well to produce while drilling proceeds, paves the way to testing while drilling, providing valuable information about the productivity of the formation while it is being drilled.
5. What are some of the main directions that you see for the future?
There are two main directions.
We would like to see Directional Coiled Tubing Drilling be the service of choice for re-entry drilling. The small surface footprint, ability to deploy through the completion (presently our smallest tool is 3.192 in OD, but an even smaller on is on the way), and ability to drill without damaging depleted formations make it ideal for this work.
The other significant direction is the drilling of new laterals in shales. Published research indicates that drilling an entire new lateral underbalanced can, in some formations, eliminate entirely the need for post drill fracture stimulation.
6. How can someone get started with Coiled Tubing Drilling?
Give us a call! Talk the project over with us. Our ability to create an interactive software model of the project means that we can very quickly, and without commitment, give our opinion as to whether or not a project is feasible for Coiled Tubing Drilling. If it is feasible there are a number of ways we can work with you to progress the project. We partner closely with a number of CT Rig providers. If you already have a relationship with a Rig provider whom you would rather use, that’s not a problem. We can perform the necessary work to prepare anyone’s rig to run our tools.
Learn more at the "Making Money with Mature Fields" Geosciences Technology Workshop, 5-6 October 2016, Houston, Texas. More information coming soon!