Downhole Telemetry From the User's Point of View
Authors: Kamp Anthony W. 
Published: December 2007

Kamp, Anthony W., Koninklijke/Shell Exploratie en Produktie Laboratorium

This paper assesses the benefits of downhole telemetry on the basis of extensive discussions with field experts. A survey of the experience gained with commercially available sensors for directional measurement while drilling (MWD) shows that extension of this market to onshore applications requires simplified and low-cost tools, making them economical at about 10% rig-time saving. Furthermore, an estimate is made of the effects of other operational applications of telemetry.Improving drilling efficiency (saves approximately10% rig time*).Directional control (saves approximately 10% rigtime*).Improving drilling safety (has indirect effects).Logging while drilling (saves approximately 5% rigtime*).

The economic outlook for these other applications against the background of the commercial downhole telemetry market is promising. This applies to reliable systems in modular standardized form, which are costly and difficult to obtain.

Introduction

Many companies are involved in downhole telemetry or MWD developments. Although the literature may give a different impression, few have been able to develop a reliable service to meet requirements of the operator at reasonable cost. This paper summarizes views of Shell-associated operators (rather than suppliers) on the benefits, limitations, and future of MWD. They are concerned with analyzing a potential induction of the total drilling costs and increasing earnings in the production phase by the use of MWD information as follows. In exploration, appraisal, and development drilling operations, MWD can make drilling more efficient as a result of optimized rock penetration, improved safety, and improved steering of the bit. In the longer term, less-conventional methods of dulling may be feasible with MWD e.g., horizontal drilling in low-permeability pay zones and by obtaining logs from an MWD tool. In exploration and appraisal drilling operations, early information enables timely decisions concerning progress, testing, and casing setting in a well. In development drilling operations, drainage becomes more efficient as a result of better-quality wells i.e., less formation impairment and optimized drilling with improved target definition. To see what these effects mean in practice, the potential incentives for downhole telemetry while drilling were outlined. On this basis, field experts from 10 companies operating in various parts of the world estimated the potential effect of MWD on their specific drilling operations. The results were quite different for the various areas and people involved. This project has led to better appreciation of MWD justification for an operator, which is discussed in the next section.

Operator's Requirements for an MWD System

The operator's purpose is to "make hole" for specific objectives without getting into trouble. Hence, unfamiliar equipment is used reluctantly. Before using such equipment, operators may ask MWD suppliers the following main questions.1. Does the system provide the right information i.e. as requested by the operator and is it of real value to the drilling operation?2. Is the system reliable, field-proven, and of goodreputation?3. Is the system locally available with good service i.e., through a company with proper equipment, good personnel, and preferably with international operations?4. Is the system suitable for use on a specific drillingrig, requiring no or minimal extra staff (offshore), and acceptably priced?5. Is the system competitive with systems of other suppliers?

JPT

P. 1792^