Abstract

Sabriya 72 (SA-72) is a deep vertical high pressure well originally drilled in North Kuwait in 1983 which was temporarily abandoned due to stuck pipe. The last intermediate casing was set prematurely above the base of a critical highly pressured salt section. Due to the importance of the SA-72 location to appraise a newly discovered field, economics favored re-entering this well in 2003 and sidetracking directionally to intersect suspected fractures in the Jurassic Marrat carbonate formation.

The main challenges of this well were to sidetrack to the target depth without compromising well integrity, and to test the well with the largest production liner possible.

In order to meet these challenges, several first time technologies to Kuwait Oil Company were planned and utilized in this well. These new technologies included running a 6" × 7 3/4" expandable liner, as well as utilizing Near Bit Reamers (NBR), bi-center bits, and slim hole sidetrack techniques to prepare the hole for the expandable liner and to drill to total depth afterwards. An unprogrammed 6" × 7 3/4" expandable patch was also installed in the 7 3/4" production casing to repair a severely damaged area.

Due to unforeseen complications, this is also the first time that the expandable technologies have been used in a 19.7 ppg mud weight. Although the expandable tubulars were run successfully, severe lost circulation after drilling below the expandable changed the course of action and thus the final completion of the well.

This paper will be a case study that discusses the planning, implementation, and lessons learned from the utilization of expandable technology on SA-72.

Introduction

The Jurrasic structures in North Kuwait fields have long been unexplored. Two wells were drilled in the 1980's in Raudhatain (RA) and Sabriayah (SA) fields of North Kuwait, RA-61 and SA-72, respectively. Both wells were abandoned due to stuck pipe. A new well, SA-153, targeted the Marrat Jurrasic structure in the Sabriya field in 2000 and was tested as a new discovery. This well was located in the up thrown fault block of the structure, which is a fairly porous and fractured carbonate formation.

The location of SA-72 in the down thrown fault block made it a good candidate to further investigate and test the potential of the Marrat formation in the Sabriya field. Economic calculations showed a possible savings of over 50% to re-enter and sidetrack SA-72 than to drill a new well. Moreover, drilling a new well would have delayed the decision process to further delineate the Jurrasic system in Sabriya field due to the projected additional time required.

Originally, SA-72 was a Khuff target well drilled to a total depth of 18610'. In this well the 7 3/4" casing was prematurely set in the critical, overpressured Gotnia Salt section, where at least 50' of the salt was left exposed below the 7 3/4" casing shoe. A 6 1/2" hole section was subsequently drilled below this shoe to the Khuff formation with a maximum mud weight of 16.4 ppg. The exposed salt section below the shoe had to be reamed open almost every time a trip was made in or out of the well. After reaching TD and during the final wiper trip prior to running a production liner, the BHA was stuck across the Lower Marrat formation. After several fishing attempts it was decided to plug and abandon the well. The well was left in the condition illustrated in Figure 1.

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