Optimization of the handling and racking processes in Deep Offshore Operations
Authors: Bonnefoy P. , Duhen T. , Kerbart Y. 
Published: October 2008

The construction of new deep offshore units provide opportunities to implement innovative approaches providing an global optimisation of the drilling process taking place during the well construction and resulting in significant cost savings. A global analysis of the drilling process for Deep Offshore operations indicated some areas where cost effective optimisation was possible. That is the case of the preparation of the drilling assembly. This paper describes the main features and operating principles of an innovative racking system together with the expected economical and operational benefits in term of efficiency and safety of the drilling process. This new design concept and associated operational procedures will be installed on a drill ship presently \\l1der construction and operating up to 3000 m of water. The main features of this new "dual handling" system are:two independent workplaces :well center and an auxiliary mouseholetwo independent racking systems

Compared to conventional design this new system provides, at a reduced cost and with minimal technical changes, an optimisation of drilling operations throughdouble activity on rig floorpick up and lay down of string elements while working at well center including tests of MWD, LWD, down-hole motors or turbinescomplete handling and racking system redundancypick up tubing and casing (up to 9" 5/8) in doubles

Introduction

Driven by operators needs, technological progress and associated costs reduction have made possible the drilling in deeper water depth zones. This technological factor associated with previous experience of deep offshore operations, permitto implement reliable innovative technological solutions, contributing effectively to a reduction of operational costs in deep offshore operations. The past experience of the Contractor and Operator have been the basis for an adequate analysis of deep offshore drilling operations which is needed for the definition of relevant improvements to be done. Pride-Foramer has been recently chosen by Elf for the construction of a drill ship capable of operating worldwide by 10,000 ft water depth. The drillship has especially been optimized for Offshore West Africa, Gulf of Mexico, Offshore Brazil and South East Asia (ref. I). For this construction and in view of an optimized use ot this unit, Pride-Foramer, sharing operator's involvement in cost reduction, is committed to promote improvement of well construction perforn1ances concerning drilling and installation of completions and Xtrees. The basic idea is to reduce as much as possible thehandling times, unproductive times which are part of the well construction critical path. After analysis, the preparation of string assemblies was considered as one domain where optimization was possible. Indeed, with minimal technical changes, by adding auxiliaryequipments pern1itting to work in parallel during some operations, an effective time reduction of the global well construction process was possible.

Analysis of Offshore Operations

A synthesis of typical operational times for drilling and completion activities in deep offshore operations (excluding well testing) can be found in tables I and 2 (drilling + completion). Activities have been divided into six categories: Drilling and Coring, Tripping the drillstring, Casing, Riser-BOP Running, landing BOP-Well Head Works, completion. Table 1 provides typical estimations assuming the use of conventional handling system and table 2 estimations obtained using the "dual handling"system.