Remotely Operated Cementing Methods for Drilling With Liner Installations

Abstract

Mature fields present major challenges for drilling and the installation of casing and liners. These fields typically exhibit depleted intervals with narrow pressure windows located in the same hole interval, posing unique challenges for installation and cementing of casings or liners. Fluid losses in the depleted intervals coupled with the inability to manage the annular fluid level can lead to differential sticking and stuck pipe scenarios while using conventional drilling and casing installation methods. Furthermore, even if the casing or liner is landed at its planned depth, the subsequent cementing operation offers its own challenges with little chance of a positive outcome with conventional cementing methods potentially resulting in significant non-productive time (NPT).

These challenges provide fertile ground for the development and implementation of unconventional drilling technologies such as drilling with liner (DwL) and managed pressure drilling solutions to enable operators to meet their well construction objectives where conventional methods have little chance for success. The DwL process allows a hazard interval to be isolated and cemented in a single trip resulting in less risk and exposure compared with the use of conventional drilling methods. This technology has found its niche in wells where zones must be drilled which have a high probability of hole problems such as fluid loss, narrow drilling margins, depletion and instability, leading to excessive NPT. Still, the subsequent cement job typically involves pumping cement through the casing bit into the liner-open hole annulus with the hope of obtaining the required formation integrity test (FIT) value while also satisfying annular and zonal isolation requirements

A North Sea operator has experienced sustained annulus casing pressures in wells in a mature chalk field. This is due to lack of cement isolation and cement channeling after a 9-5/8 in. drilling liner is drilled through a pressured shale overburden interval into a depleted chalk interval with the liner typically becoming stuck. Conventional liner cementing methods were not providing the necessary hydraulic or mechanical isolation over the life of these wells due to the very narrow pressure windows exposed in the drilling liner interval and the lack of ability to rotate the liner above the liner stuck point during cementing. An international oilfield service provider collaborated with the operator and together designed a cementing solution using strategic deployment of multiple remotely operated cementing port collars on the drilling liner to meet the required cementing objectives. Also included on the drilling liner are a metal expandable annular casing packer and hydraulic casing swivel designed and configured to be fully compatible with the planned hydraulic DwL system. This paper will present the DwL system design process along with the related procedures enabling the cementing port collars to be remotely activated with the liner having the ability to be rotated above the stuck pipe section and cementing operations commencing directly after reaching total depth.