Reducing Non-Productive Time Through the Use of Solid Expandable Tubulars: How to Beat the Curve Through Pre-Planning
Authors: Cales Gerry , Grant Tom , Book Larry 
Published: October 2008

Solid expandable tubular technology was commercially introduced to the oil and gas industry over four years ago. With more than 250 wells having been completed using solid expandable tubulars, this technology has made the transition from novel concept to accepted downhole application. As the oil and gas industry continues to push into deeper water, and the cost of wells increases, it is imperative that every effort be made to drill wells to depth as quickly and efficiently as possible. An obvious challenge for all operators to overcome is to reduce or eliminate flat time on the drilling curve.

This paper will explore how the application of solid expandable tubulars enables drillers to reduce both the flat time on a drilling curve and steepen the angle of the curve. The result of this synthesis will enable the operator to reach total depth (TD) in less time. A probabilistic approach will be used to demonstrate the value of expandables.

This paper presents case studies where solid expandable tubulars have reduced or eliminated flat time on the drilling curve and show how the technology has enabled faster drilling of wells. Decision analysis will be used to demonstrate how solid expandable tubular technology can be deployed to reduce costs significantly when an operator faces a myriad of well problems. Through the use of expandables, operators have shown that many technical challenges can be overcome in a cost effective manner. Solid expandable tubulars have enabled a step change in how wells are drilled. This paper addresses several ways in which those changes have occurred and how the technology continues to move forward.

Introduction

Operators are all too familiar with the flat time on the drilling curve that occurs on drilling projects due to changing bits, setting casing strings, fighting lost returns, and so on. A certain amount of flat time can be expected, of course, but non-productive time can be controlled and reduced if an operator does a thorough job of pre-planning, especially in instances where unfavorable formations are likely to be encountered. Based on the experience of various operators in different drilling environments, planning in the use of solid expandable tubulars can be a key to reducing flat time.

The Drilling Curve

The drilling curve has been around for years. When wells are in the Authority for Expenditure (AFE) generation stage, the curve is in its ideal form, steep with few horizontal lines, all of which are necessary products of the drilling process; rigging up, installing blowout preventers, running casing, cementing, etc. As the actual drilling of the well progresses, in many cases the actual curve starts to diverge from the ideal, with the slope of the curve flattening. As the curve flattens, actual cost of the well versus the AFE starts to diverge as well. In many cases this flattening of the curve is a direct result of fighting mud losses, stuck pipe, or any of a myriad of other issues that prevent rigs from making hole.