Life-Cycle Analysis & Optimization of Intelligent Well Systems for High Reliability

John A Hother, Proneta ltd; SPE 77630; SPE Annual Technical Conference held in San Antonio, Texas, 29 September – 2 October 2002.

ABSTRACT

Reversionary Mode Analysis (RMA) was used to analyse the reliability of the whole life-cycle of a proposed well development, so that the risks associated with different well designs could be quantitatively compared by an operator (the project’s sponsor). The technique combines engineering analysis and economic modelling in a systematic and rigorous way. For this project, we needed to cover both the well construction processes and the well production systems. This is a new development of RMA, which provides a specific version of the technique for operators to use, termed ‘RMA level-1’. For a complex project such as a deepwater intelligent well, the reliability of the construction processes is at least as important as the well systems during the production phases, so the analytical technique must handle both these aspects in a seamless, integrated manner.

To ensure proper coverage of the whole life-cycle, this extended form of RMA started with a new set-up – defining the scenario. This defines the constituent aspects of the well life-cycle for each development option, covering activities defined by process flow diagrams, and equipment defined by system block diagrams. Then engineering analysis of the failure modes determines cause, effect and probability. To confirm the validity of the analysis, the estimated probabilities of failure were checked with alternative sources.

The economic model was produced, quantifying in financial terms the consequences of a whole range of different types of failure. The analysis software consolidated all the failure mode data with the economic model.

The results in ‘risk-Dollars’ highlighted the aspects that are critical to the project’s viability, and provided a good basis for comparing different well options. The rigorous data structure provided the capability to ‘drill-down’ into critical aspects, to identify key causes for which mitigating measures were needed, which may occur at any stage in the life-cycle.