Core and NMR Guided Formation Evaluation of a Tight Clastic Reservoir

The evaluation of tight clastic reservoirs challenges not only the accuracy of well logging techniques, but also routine and special core analysis. Traditional formation evaluation approaches, often fail to adequately characterize tight sands or carry a large and sometime unacceptable uncertainty in the results. During the on-going exploration and appraisal stage of the field, significant amount of data was acquired to build a robust static and dynamic model. Core acquired from the reservoir section was carefully analysed and integrated with other multidisciplinary data in order to reduce the level of uncertainty in critical formation evaluation properties like shale volume, porosity, permeability and saturations. These formation evaluation properties are considered as the basic inputs for static and dynamic modelling. The only way to make the models robust is by reducing the uncertainty associated with these critical petrophysical parameters. This can be achieved by planning, executing, and screening proper core analysis protocols and the integration with cross functional data like NMR logs. Additional confidence on the results comes from analogue field data.The objective of this paper is to document some of the challenges and how, through application of optimized integrated formation evaluation techniques, tight sand reservoirs had been characterized.