Abstract Reconciling formation porosity and fluid distribution estimations in carbonate and shaly-sand systems represents a problem that log analysts and petrophysicists face in dealing with well log interpretation. The problem becomes especially challenging when data from conventional (e.g., density, neutron, gamma ray) and non-conventional (e.g., Nuclear Magnetic Resonance (NMR), multi-component induction) instruments are available and need to be combined in a consistent interpretation. Also, the use of effective and/or total porosity petrophysical models may lead to confusion and improper use and interpretation of those quantities. The paper proposes petrophysical interpretation models for use in the evaluation of carbonate and shaly-sand reservoirs. They allow for effectively and consistently combining the various measurements under the framework of either effective or total porosity. Simultaneous and sequential solutions of the petrophysical models are proposed leading to consistent data integration and reconciliation of porosity and fluid distribution across the various available log measurements. The proposed interpretation method focuses on the integration of NMR with conventional log measurements in carbonate and shaly-sand environments. With sufficient log data, rocks having complex mineralogy can be interpreted in terms of mineral volumes, irreducible and moveable water saturation, and hydrocarbon saturation. In a shaly-sand environment, results are expressed in terms of sand, shale and fluid saturation distributions. The paper describes the mathematical formulation of the petrophysical model as well as the applied numerical techniques. Optimal interpretation results are achieved using forward modeling and a constrained, quality-weighted error minimization technique. Field data examples are presented that show the ability of the interpretation models to reconcile porosity, fluid type, and fluid distribution in the pore space.