RIASSUNTO
Abstract
This paper describes development and testing of a new guide shoe mill (GSM) for intervention fishing services in conjunction with the well construction's drilling hazard mitigation. Primary application of this mill is for milling guide-shoe left in the well by the solid expandable running tool system. The traditional milling direction is downwards. The new mill was designed to mill upwards in the reverse direction, thereby clearing the restriction and restoring the well bore casing drift internal diameter (ID). This paper covers development of guide shoe mill, failure analysis on a test well, and improvements done in various steps to prevent future failures . Use of Finite Element Analysis (FEA) models and extensive lab tests are also discussed.
The ability to maintain stabilization while milling in a high vibration environment and to remove cuttings to the surface were two major challenges. The guide shoe mill out tool provides stability, efficient well cleaning to restore casing drift ID, thus saving on non-productive time (NPT) and other drilling related costs. The study of failure prevention has lead to better technology applications and process improvements. Successful results obtained from lab testing (including test rig) lead to potential application in other areas such as selective section casing patch removal.
Introduction
The need for expanding pipe Maximizing the return on investments (ROI) while reducing the NPT and other drilling related costs are key objectives for solid expandable tubular development program. And achieving the monobore well could be considered as the ultimate promise of expandable drilling liner technology, where well telescoping or slimming of the wellbore is either greatly minimized or entirely eliminated. Achieving a monobore well design provides many benefits such as : maintaining constant hole size when adding casing strings, slimming top-hole casing sections, which reduces cost and surface footprint, reducing the risk of failure to reach TD thus drilling previously undrillable wells, and potentially higher ROI. In other words, the well can be completed with a larger completion leading to higher production. The solid expandable system also helps mitigate drilling hazards by isolating problem zones. Examples of trouble zone are
the subsalt rubble zones, lost circulation zones, overpressured formations, zones with shallow flows and premature casing sets.
Various pipe expansion scenarios-
The four common metal to metal expansion systems are the Open-Hole Liner, the Monobore Open-Hole Liner (MOHL), the Cased-Hole Liner, and the Monobore
Open-Hole Clad system. Figure 1 show various types of solid expandable systems.1