Abstract

A new generation of fire-resistant wellhead equipment has been developed for offshore platforms. This cooper presents the design concepts and principles of operation of this new equipment, and it describes the principles of operation of this new equipment, and it describes the engineering approach taken during its development.

These new wellheads and Christmas trees have survived numerous laboratory fire tests which simulated offshore platform fire conditions. No leakage was permissible during the test burns nor during the subsequent cooldown periods. The laboratory fire test results confirmed the performance periods. The laboratory fire test results confirmed the performance predicted by computer Finite Element Analysis and verified the design predicted by computer Finite Element Analysis and verified the design procedures employed. procedures employed. This new fire resistant wellhead equipment promises to significantly reduce the fire hazard associated with the production of oil and gas from offshore platform wells. platform wells.

Introduction

The "state-of-the-ort" for fire-resistant petroleum equipment has advanced rapidly during the last few years. This advancement has been driven by the petroleum, industry in response to several catastrophic offshore platform petroleum, industry in response to several catastrophic offshore platform fires.

On many offshore platforms, production wells are closely spaced to minimize deck area requirements. Thus, should a fire occur on one well (typically during workover operations), adjacent wells con quickly become overheated to the point of failure. Leakage from these adjacent wells can cause the fire to increase in intensity and spread to other wells in "chain reaction" fashion. Such fires con result in the loss of the entire production platform. The dire consequences of such disasters emphasize the importance platform. The dire consequences of such disasters emphasize the importance of fire-resistant (F-R) wellhead equipment.

The petroleum industry responded by developing a recommended fire test specification for valves, API RP6F, in 1978. RP6F is now in its third edition, reflecting the continuing evolution and escalation of fire- resistance standards. During the past, three years, even more demanding "improved" fire test specifications and acceptance criteria have been developed by a major oil company. Table 1 reflects the basic differences between the original API RP6F and the new "improved" F-R specifications. Note "that the "improved" specifications require significantly higher test temperatures and allow no leakage during or after the fire test The "Improved" specifications are already being voluntarily adopted by other major oil companies and may become the "standard" fire-resistance criteria for wellhead equipment in the future.

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