Steven Rosenberg, Kenneth Kotow, and Jim Wakefield, Subsea Drive, LLC; Samuel Sampietro and Blake Hulett, Mississippi State University
This paper was prepared for presentation at the IADC/SPE International Drilling Conference and Exhibition held in Galveston, Texas, USA, 8–10 March 2022.
This paper was selected for presentation by an IADC/SPE program committee following a review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the International Association of Drilling Contractors or the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the International Association of Drilling Contractors or 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 International Association of DrillingContractors or 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 IADC/SPE copyright.
Abstract
Drilling hazards in deepwater riserless intervals include shallow water and gas flows, disassociating gas hydrates, lost circulation, and formation instability all of which are particularly challenging without a proper mitigation strategy. Unmitigated, these hazards can result in well control events, inability to get casing to planned depth, poor cement jobs, and a lack of structural integrity for subsequent BOP and wellhead installations, and even the loss of the well. This paper introduces a paradigm shift in deepwater well construction where the structural casing is installed significantly deeper via a subsea riserless casing drilling system to setting depths based on established pore pressure and fracture gradients. This casing drilling system will replace the established method of jetting in the structural casing and then drilling the subsequent hole section above the next shallow drilling hazard and installing the next casing or liner. Casing drilling will enable the mitigation and isolation of shallow hazards while running casing in a single trip. The practice of casing drilling is well-established in inland and shallow marine environments for drilling efficiency and drilling hazard mitigation. Its application in the deepwater environment requires the development of new technology. This well design approach and the use of casing drilling could eliminate multiple deepwater riserless strings-allowing the high-pressure wellhead housing and its conductor to be set significantly deeper.
The jetting process is technically limited to a setting depth about 300-ft. below the mudline. This process uses mud motor technology without pipe rotation to "push" the conductor into the seafloor which can be insufficient when drilling harder sediment. The jetted structural casing requires a consolidation or soaking period for the soil to settle and strengthen after reaching its setting depth. This w+U- can require the jetted conductor to be held in place for a period of a few hours to as much as 48 hours to attain the required resistance force. Jetting practice, with its limited setting depth, had become an accepted practice for the vast majority of subsea drilling operations. It is this depth limitation combined with the offshore practice of designing well geometry from top-down that manifests the drilling problems for the narrow drilling operating windows in deepwater. The shallower the 36″ casing is set and the requirement to set casing strings above anticipated shallow drilling hazards causes a large number of casing strings of ever-decreasing diameter to reach the programmed total depth of the well plan.
Downloaded from http://onepetro.org/SPEDC/proceedings-pdf/22DC/2-22DC/D021S011R002/2649962/spe-208793-ms.pdf by Steven Rosenberg on 19 March 2022