Information on fractured reservoirs is often controversial. Engineers see lost circulation, negative skin and fracture well test signatures. Geologists see only matrix properties in their cores. Geologists see fractures but engineers see only radial flow on their well tests. In many cases, the two lines of information concur and the evidence is uncontroversial. In other cases the information is not so clear. Engineering data is notoriously non-unique and because carbonate reservoirs have such high heterogeneity—over 30 possible forms of porosity—and many ways this can be connected (or not!) this is a real challenge. What is seen by geologists in small cores may not be seen in larger well tests. Alternatively what is ‘seen’ in the well tests may bear no link to the observed rocks. It is in these circumstances that the two specialists need to come together and understand each others points of view and the limitations of each other’s data. This requires specialist knowledge with geoengineering insights to try and reach unification of geological and engineering models. All models are wrong—but the one both disciplines agree with is probably useful.