The paper will discuss aspects of deep water drilling, with a special concern to harsh environments.
The recent developments and challenges in exploration drilling, subsea development and floating production systems will be thoroughly reviewed. Although the coverage will be world-wide, the examples of technology need will be taken from the newly started developments of the northern Atlantic sea west of northern Europe.
The environmental aspect of such developments in deep water and harsh environments will be given attention.
The paper will end with a discussion of the future need for research.
Many of the current deep water areas of interest consist of thick piles of poorly consolidated, young Sediments that are proving very difficult to drill. Low formation strengths, sloughing shales and safety considerations put such strong demands on well programmes that data collection is frequently minimized. The tough conditions also result in variable data quality and greater associated uncertainties in the interpretations made from these data. Describing the reservoir is further complicated by the high cost of drilling under difficult conditions and that development plans are based on a minimum of appraisal wells. Furthermore, the majority of the young reservoirs found in deep water areas today were themselves deposited in deep water where many different physical factors, e.g. basin type, source areas, local topography during deposition and diagenetic history, are known to have controlled the final geometry, stratigraphic architecture and the internal heterogeneities of the productive horizons.
For these reservoirs it is critical that one establishes - Good ties to the seismic. - A correct picture of the different scales of heterogeneities. - Detailed biostratigraphic control to aid correlation. - A correct understanding of the sedimentary facies and their sequential distribution, the productive capability of the formation and the nature of the reservoir fluids.
Each of the data collection types noted here can be problematic within unconsolidated Sediments. This therefore creates demands from the geoscientist that the drillers provide stable holes that allow sufficient time to collect good quality log data before casing.
In addition coring equipment should give good recovery of very loose Sediments and test design should allow significant flow to measure the full flow potential accurately, an essential parameter in production unit design.
The first floating production system started operating in the North Sea in 1975. Since then, floating production systems have gained more and more acceptance. Today there are more than 90 floating production systems in operation o
