Abstract

This paper describes the use of process simulation models to evaluate alternative drilling programs, and specifically to quantify the band of uncertainty in time and cost. The discussion also includes consideration of the interaction between the drilling program and the selection, design and installation of the process facilities.

It is recognized that deepwater drilling operations are complex and risky endeavors. The cost of these drilling operations can represent a very significant proportion of the total field development, and so it is essential to understand the causes and magnitude of this risk. Modeling using Monte Carlo simulation is a natural tool to assess these risks and has been available for many years but, owing to the complexity of building and maintaining the models and evaluating the results, it has not often been applied to deepwater drilling.

The authors have used the SLOOP simulation software to assist in planning and evaluating deepwater programs both West of Shetland and in the Gulf of Mexico. These were used to help plan an exploration program, and to evaluate alternative development drilling options. They were also used to help evaluate spar platform alternatives for a Gulf of Mexico field development.

A key consideration in using simulation is the presentation and evaluation of the results. Presenting risk-based evaluations in a meaningful and concise format is difficult. With the use of SLOOP and interfaces to spreadsheets, ARCO and Vastar (now both merged into BP) and BMT have developed an approach which provides the results in a compelling and concise manner. The simulation results presentations were key ingredients in planning the West of Shetland Block 204 exploration program and in selecting the final development scenario for Horn Mountain.

Introduction

Deepwater operations are complex and risky endeavors. Specifically, it is very difficult to estimate the impact of the metocean environment (wind, wave and current) on drilling operations. This is particularly important in areas with harsh conditions, as it is essential to understand the magnitude and causes of the risk, in terms of both timing and cost. Modeling using Monte Carlo simulation is a natural tool to help quantify the impact of this type of risk. Though the method has been available for many years, it has not often been applied to operations such as deepwater drilling, but with the availability of fast and very economical computers and the development of convenient simulation software, simulation can now readily be applied to deepwater operations

In this paper we discuss the use of this simulation model by ARCO and Vastar (now both merged into BP) to assist in planning and evaluating deepwater drilling programs both West of Shetland and in the Gulf of Mexico. For the West of Shetland operations, simulations were performed to plan the exploration program and to evaluate alternative development options. In the Gulf of Mexico, Vastar recently used the simulation to model alternatives for the Horn Mountain development options.

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