Abstract

Crucial in well life cycle management is an analysis of technology and economy balance from the beginning (well project) to the end (well abandonment and environment sanitary improvement).

On the basis of over one thousand drilled oil, gas and geothermal wells (since 1950.), on-shore and off shore, over fifty thousand completions and workovers and about five hundred abandoned wells, an overall analysis will be done to state problems and solutions considering the technology to economy balance.

In the paper we will try to point out phases in well life cycle that are of the greatest influence on economy.

Finally, the optimal way of well or entire field abandonment and produced waste management will be discussed from technological and economical standpoint.

Introduction

Well is the main object that enables the communication with the reservoir achieving a desired amount of production with minimal costs. The well cycle begins with well drilling and completion continues with workovers, measurements, recompletions and finishes with well abandonment. For the same reservoir/layer once drilled well can be used for production, injection or can be abandoned as negative one. Such are the phases of the reservoir life cycle management; drilling, exploration, development, secondary and tertiary methods for hydrocarbon recovery, abandonment and possible use for waste disposal.

Managing the system during all this phases requires multi-disciplinary approach of all participants. So-called System Analysis1 defines the development of the method of planning, designing and problem-solution. The essence is in breaking down any problem, operation or equipment, into basic categories. This basic categories of the total system (an on-going process composed of a set of components with given relationships between the components and their attributes and a given number of constraints with the objective of producing a specific result in a given environment) are: objectives (defines the purpose for which the system components, attributes and relationships have been organized), operational environment (the set of all components outside the system that can influence the system), resources (that on which the system depends for supply or support inside the system) and constraints (a limitation placed on the operation of the system).

The most important is to realize how each operation in a well program affects any other, especially on well productivity or overall reservoir production. Without the analysis of the system, from the well location, construction (casing design), use of optimal drilling technology and completion, the main objective of the well (maximal productivity) will be not achieved. Feedback and control through feedback is present in all segments and analysis but is the most important in production operations. That means the analysis of production data and characteristics, well testing, equipment repair reports etc. The comparison of the expected well performance, with recorded one will show the efficiency of the system. The update of the feedback and the control through it must be done by the management ready for changes and capable to define and plan steps before the need for change or correction actually exists.

None of this can be done without the changes in the level of knowledge and technology development during the life cycle of the well. So the velocity of adaptation and adoptation of new knowledge and technologies can greatly improve and extend the life cycle of the well.

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