SPE 116838 Feasibility Study of Combining Drilling with Casing and Expandable Casing Hendry Shen / University of Stavanger – Bernt Aadnoy / University of Stavanger, Norway Copyright 2008, Society of Petroleum Engineers This paper was prepared for presentation at the 2008 SPE Russian Oil & Gas Technical Conference and Exhibition held in Moscow, Russia, 28–30 October 2008. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract Rig cost, service company rates and materials costs have gone up significantly in accordance to the oil price. Industry is therefore continuously searching for new technologies to make the drilling of wells safer, more efficient and economical. This paper will explore the possibilities of combining two existing technologies to meet these challenges. Drilling with casing (DwC) uses standard casing as the drillstring and leaves it in place to case the well. It has a potential of saving of rig time by eliminating drillstring tripping and also minimizing downhole problems. With expandable technology, expanded casing can provide a larger diameter of the production casing. This can increase the well productivity. Because both technologies have similar operational procedures, they could be combined into one operation. The new concept is to use expandable casing as a drillstring which will be expanded when the target depth is reached. The conclusion of this analysis is that the drilling with expandable casing concept is possible. However, there are some technological challenges, especially on tools and on the strength of post expansion materials. The examples analyzed, indicate that we can save 39% of the operation time by running this combined technology. Expenses can be reduced through lowered rig costs and the operational risk can be mitigated. A better understanding of the technology and operational procedures will help to further reduce the risks and make the technology even more acceptable. If this new method succeeds, there will be a high potential for cost savings, higher production rates and better well control. Introduction This paper is mainly based on an academic project by Shen (2007), who investigated combining drilling with casing and expandable technology. Drilling with casing (DwC) is using standard oilfield casing as the drillstring, and leaving it in place to case the well. Expandable technology is next step of the development of mono-diameter technology. Mono-diameter wellbores may become the future form of oil well construction. Because both technologies have similar operational procedures, they could be combined into one operation. The concept is to use expandable casing as a drillstring which will be expanded when the target depth is reached. Ideally this operation can be performed in one or two trips. To obtain a larger production casing size and to solve the lost circulation could be achieved at the same time. Larger production casing size will allow a higher production rate which will compensate the operation cost. One should understand that to combine both technologies may also bring disadvantages. In the following we will investigate this coupled concept. Specifically, the objectives of the work are as follows: • To see the feasibility of combining drilling with casing and expandable casing methods. The investigation will be performed both on technical, risk and cost. • To propose the appropriate application for this method. Some questions that need to be answered in due course are : • How can this combined method works? • Are the expandable casing connections strong enough for drilling with casing? • How does the expandable casing perform after being used for drilling? • What are the expandable casing properties that need to be considered? • Is the solution cost competitive? • Are there any limitations this process? • What is the risk for the combined method? Industry Overview Drilling with casing This subject can be divided into two general areas: 1) Casing Drilling, where the casing is extended to the surface and is
