Abstract

A new adaptation of a proven flow simulator is aiding blowout contingency planning. Most important wells require a blowout contingency plan. Part of that plan includes relief well intervention. The flow simulator distinguishes between workable and difficult intervention schemes. It suggests any needed modifications in original well design. And it makes crisis management quicker, cheaper, and more effective. This paper describes the power of using this simulator for both surface and relief well hydraulic kill planning.

Introduction

Planning kill strategy for a 1989 underground blowout in the North Sea required development of an improved flow simulator. The hydraulic kill simulator was based on the industry-standard, two-phase pipe flow model, OLGA. After the project, the planning team realized that they gained considerable advantage from using a transient two-phase flow simulator for comparing various kill scenarios. Since then, OLGA-WELL-KILL simulator has been used successfully for a number of intervention design plans. In the event of a major blowout, the speed at which rescue and intervention equipment and personnel are mobilized is critical for the preservation of life, property, and the environment. The first priorities of these emergency operations are personnel evacuations, oil spill containment, and salvage of the reservoir, platform and well. To respond quickly and efficiently to these emergencies, operators have devised and supported emergency response plans with the necessary resources and infrastructure to react immediately if required. Unfortunately, the only way to test the true effectiveness of a response strategy is during an actual emergency. Only after the events can one evaluate results and make modifications. It is this reasoning, in the aftermath of recent major blowouts in the North Sea, that operators and regulatory authorities are re-evaluating the status of emergency response plans under their jurisdiction. Their purpose is to assure that lessons learned from these events are documented and that all operators incorporate appropriate improvements into their emergency procedures. One component of this post evaluation process indicated that additional preparation for regaining control of a blowing well is justified. Even though the probability of a blowout is small, the consequences in safety, cost, and pollution could be catastrophic. For these reasons, "solving the problem" contingency plans are being added to the existing emergency response plans. This effort will eventually include surface, subsea, and relief well intervention. A primary objective of this contingency planning process is to evaluate the current level of technology and operational expertise available for a blowout intervention operation. Shortfalls can then be identified and appropriate action taken to reduce the deficiencies. One problem identified early in this evaluation was the difficulty in analyzing heavy mud hydraulic kills, in a two-phase blowout flow regime, with existing steadystate flow models. These models cannot easily evaluate the time transients of the kill process or deal with complicated multiphase flow regimes, flow paths and interaction with the reservoir.

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