Selection Criteria for Subsurface Safety Equipment for Offshore Completions
Authors: Krause W.F. , Sizer P.S. 
Published: December 2007

A closer look is given here to the relationship of the packer, landing nipples, and circulating devices to the safety equipment used in offshore completions. Particular attention is given to the selection of down-hole safety devices.

Introduction

The increase in offshore activity within the petroleum industry has brought with it some new and unique problems. Some of these have been resolved through problems. Some of these have been resolved through the modification of existing techniques and equipment, whereas others have necessitated an entirely new concept in completion. This paper presents an analytical approach to the selection of down-hole safety equipment for offshore completions, and is limited to only those safety systems utilizing a surface-controlled hydraulic system. The relationship of the packer, landing nipples and circulating devices to the safety equipment, and such variables as single or multiple completions, gas or fluid, volume and pressure as factors influencing the final decisions are pressure as factors influencing the final decisions are discussed, as are the actual installations and the relationship between operating and service companies.

Three Basic Phases

A completion must be designed to satisfy the requirements of the three basic phases of a well's lifecompletion, production, and workover. production, and workover. Completion

Because of the extremely high cost of drilling offshore, the equipment should be such that it can be installed and the well circulated and put on production in a minimum of time.

Production Production In considering an offshore completion, it is mandatory to try to foresee any future conditions or probabilities that may necessitate an early workover. Equipment and techniques must be selected that will help to eliminate the costly pulling of pipe. Proper use of such wireline techniques as plugback, squeezing, and reperforating must also be considered. A few extra dollars spent on initial completion could be money well spent, if just one trip of the pipe is avoided.

Workover

In this stage of a well's life the tubing is usually pulled. Here, some thought must be given to how the pulled. Here, some thought must be given to how the well will be killed and whether or not pipe rotation is required. Only after all aspects of the well's producing life are considered should a completion be producing life are considered should a completion be designed and recommended. The producer is responsible for setting the limitations within which the equipment manufacturer and service company are to work. Following are some of the factors that must be determined before any recommendation is made:Will the well be completed as a safe or as a dual?What size casing win be used?Is a kill string required?Can the well be produced in the casing?Will wireline or produced in the casing?Will wireline or through-tubing work be required?

Only the producer can determine these factors. When these questions have been answered, and when the producing characteristics of the well are known pressure, fluid or gas, productivity index, presence of pressure, fluid or gas, productivity index, presence of H2S, etc.the manufacturer can then recommend a completion.

JPT

P. 793