Titanium Drill Pipe for Ultra-Deep and Deep Directional Drilling

Abstract

Abstract This paper discusses the modeling and analysis of 5, 5–1/2, 5–7/8 and 6–5/8 in. titanium drill pipe in ultra-deep and deep directional drilling programs. Using a computer based drill string simulator, modeling a representative deep directional well, titanium drill strings were compared to the same size steel drill strings using two design criteria: margin of overpull and hydraulic efficiency. Introduction Titanium has a yield strength of 120,000 psi and a density 56% that of steel's, resulting in a 1.57 improvement in strength to weight ratio over S-135 steel drill pipe. Analysis shows that the use of full strings of 5, 5–1/2, 5–7/8 and 6–5/8 in. titanium drill pipe reduces hook and rotating torque loads by approximately 40% in the most challenging ultra-deep and deep directional profiles. The use of titanium drill pipe in full or partial strings allows running larger diameter pipe to much greater measured depths and expands the effective distance an existing platform can reach without upgrades to the hoisting, rotating, or pressure systems. Previously uneconomical reserves can be accessed without costly rig and platform upgrades. Lighter weight titanium drill pipe potentially has a huge economic impact for deepwater structures where deck loads may have an exponential impact on structure size and cost. Reductions in drilling torque may allow the use of water-based mud rather than oil or synthetic-based mud, which can result in higher well productivity and fewer environmental concerns. Considered to be a significant threat to deepwater operations, riser wear can be significantly reduced through the use of lighter weight titanium drill pipe strings. This paper presents the service load benefits of using titanium drill pipe in ultra-deep and deep directional wells and provides performance characteristics for an innovative titanium drill pipe design. Extended Reach vs. Ultra-Deep and Deep Directional Drilling Enabling technologies and innovative techniques have contributed significantly to the industry's current ability to reach significant well departure distances, which is evidenced throughout extended reach (ER) projects around the world.Some of these technologies include [1], [2], [3], [4]:Use of sophisticated computer drilling simulators,Advancements in drilling fluid technologies providing increased lubricity and improved cuttings transport, wellbore stability, and formation damage resistance characteristics,Drill string and casing friction reducing tools,Drill pipe high torque tool joints and high friction factor thread compounds,Intermediate drill pipe sizes such as 5–7/8 in.,Improved hole cleaning procedures,Casing floatation and liner rotation techniques,Highly variable gauge stabilizers (H-VGS) and rotary steerable tools,Advancements in downhole measurement tool capabilities such as the introduction of pressure while drilling (PWD) tools and improved surveying and logging technology,Development and use of drill string dynamics monitoring and mitigation systems,New and improved rig and surface equipment. While these technologies have contributed successfully in pushing the ER envelope to increase recoverable reserves, significant obstacles remain to overcome when drilling ultra deep (UD) and deep directional wells of lower reach/total vertical depth (TVD) ratios generally not characterized as ER.