Imparting Directional Dependence on Log-Derived Permeability

摘要

Cost-effective, efficient production of hydrocarbons depends on accurate reserves estimates, reservoir architecture, and hydrocarbon distribution. In addition, a complete reservoir description, including both horizontal and vertical permeability, is critical to efficient development strategy. Hydrocarbon recovery efficiency depends on many factors, but one key parameter is the ratio of vertical to horizontal permeability. There are numerous ways to estimate permeability. It is now possible to estimate permeability from continuous formation evaluation measurements. However, it remains difficult to determine directional permeability. Nuclear magnetic resonance (NMR) logs are used routinely to estimate permeability, but NMR-derived permeability is based on scalar properties (e.g., φ, T_2 distributions from NMR, and bulk volume irreducible water) and is inherently a scalar property itself. Few formation evaluation measurements provide directional information. Dip and image logs provide bed thickness and layer dip information, while the multieomponent induction instrument (3DEX) and crossed-dipole shear-wave acoustic tools provide direct measurements of macroscopic formation anisotropy. In this paper, we explore theoretically and with real data the computation of permeability anisotropy. We use laminated sand models as well as macroscopic models based on the resistivity anisotropy measurements to estimate k_v:k_H ratios. In addition to multieomponent induction data, we explore stand-alone and joint interpretation of NMR property variations to predict the macroscopic reservoir permeability anisotropy.