Abstract
Significant emphasis on data quality is placed on real-time drilling data for the optimisation of drilling operations and on logging data for quality lithological and petro-physical description of a field. This is evidenced by huge sums spent on real time MWD/LWD tools, broadband services, wireline logging tools, etc.
However, a lot more needs to be done to harness quality data for future work-over and or abandonment operations where data being relied on is data that must have been entered decades ago and costs and time spent are critically linked to already known and certified information.
In some cases, data relied on has been migrated across different data management platforms, during which relevant data might have been lost, mis-interpreted or mis-placed. Another common cause of wrong data is improperly documented well intervention operations which have been done in such a short time, that there is no pressure to document the operation properly. This leads to confusion over simple issues such as what depth a plug was set, or what junk was left in hole.
The relative lack of emphasis on this type of data quality has led to high costs of work-over and abandonment operations. In some cases, process safety incidents have arisen.
This paper looks at some work-over operations carried out in a span of 10 years. Data management system is generally analysed and a categorisation of issues experienced during the work-over operations is outlined. Time lost due to data error was seen to average 1.54% but with a unit peak of 19%. An analysis is done on the wells' activity history to check for correlations. Bottlenecks in data management are defined and solutions currently being implemented to manage these problems are listed as recommended good practices.
