A NOVEL APPROACH TO NUMERICAL INTEGRATION OF CONVENTIONAL, MULTICOMPONENT INDUCTION, AND MAGNETIC RESONANCE DATA IN SHALY-SAND AND CARBONATE SYSTEMS

摘要

Reconciling petrophysical formation parameters in carbonate and shaly-sand systems represents a challenge log analysts and petrophysicists face in dealing with well log interpretation. The problem becomes especially difficult when data from conventional (e.g., density, neutron, gamma ray) and non-conventional (e.g., 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 presents different petrophysical models for use in the evaluation of carbonate and shaly-sand reservoirs, the latter with emphasis on low-resistivity laminated shaly-sand reservoirs. They allow for an effective and consistent combination of the various measurements leading to an accurate characterization of rock mineralogy, shale distribution, variation shale property, anisotropy, fluid distribution, and permeability. The proposed petrophysical models, which are tailored to integrate conventional with NMR and multi-component induction data, comprise a volumetric description of the rock, representing the fractional volumes of each rock component, and a set of response equations relating rock volumetrics with rock physical properties that are provided by the log measurements. Simultaneous and sequential solutions of the petrophysical models are proposed to facilitate the estimation of the required analyst-provided formation parameters. The paper describes the mathematical formulation of the petrophysical model as well as the applied numerical techniques. Optimal interpretation results are achieved utilizing forward modeling and a constrained, quality-weighted error minimization technique. Synthetic and real field data examples are presented, which show the ability of the proposed interpretation philosophy and methodology to reconcile formation lithology, porosity, fluid type, fluid distribution, and permeability.