Evaluation of Carbonate Formation using both Gas While Drilling and Nuclear Magnetic Resonance Log (Case study, An Oilfield Southern Iraq)

Abstract

Two wells close to each other (Well A and Well B) have been selected from the same oilfield in southern Iraq. Both wells were drilled through the Mishrif Reservoir, however, perforated within different sub-units. It was observed that one of the wells shows obvious flow naturally while the other did not notice any kind of flow. The type of hydrocarbon interpretation by Gas while drilling method (GWD), the results confirmed that both of these wells were located in oil-bearing reservoir with comparable gas profiles. However, petrophysical properties of the pore distribution and permeability using Neutron Magnetic Resonance (NMR) data in Techlog identified key differences in rock quality between the wells across the perforated intervals. Reservoir quality reveal very wide differences in performance in spite of both wells are penetrating the oil bearing layers within Mishrif reservoir. Keywords: Carbonate Formation, Gas While Drilling (GWD), NMR Log.