| Popis: |
There is a lack of general design methods for water injection schemes. This is reflected in the fact that there exists no handbook for water injection and no commercial reservoir simulators include modules for injectivity damage; even though waterflood simulation is one of their main tasks. This thesis aims at critically evaluating the current approach and suggesting better practises. The objective is to analyse the parameters affecting the performance of matrix water injection wells and critically evaluate their importance in the light of available field history. This includes a review of the injectivity damage mechanisms involved and evaluation of the prediction methods available to quantifY their reliability for real field cases. The following steps are presented: » Review of current understanding of water injection performance. ? » Review of published coreflood experiments with the aim of identifYing both main trends and the key differences. Other potential damage mechanisms are also discussed briefly. » Available injectivity prediction models are evaluated for sensitivities in the input parameters and compared against both core experiments and field performance. » Field information from more than I00 wells, operated by 15 international oil companies was acquired. The information is critically analysed in consistent manner and the main trends identified and compared to the key findings ofthe laboratory and model approaches. The field data proved generally insufficient to provide a firm correlation relating water quality and formation characteristics to injectivity decline. This comparative investigation does however, indicate the uncertainty range in the key parameters involved and does, therefore, result in an improved understanding of the injectivity mechanisms. The key findings are summarised in brief guidelines for best operational practices for water injection. Furthermore, areas of significant inconsistencies, requiring further investigation, are identified and recommendations made as a basis of research activity to fill some of the many gaps in understanding in this important topic. |
