Integration of FPWD and LWD NMR Data to Derive Continuous Permeability Log

Continuous permeability log is of great importance to the design of completion program and productivity estimation in development wells, especially the continuous dynamic permeability log. Normally the way to acquire formation porosity is logging-while-drilling (LWD) nuclear-magnetic-resonance (NMR) which is from T2 distribution and lithology independent. Since T2 distribution also has the information of pore size distribution, LWD NMR can also have the permeability. However, the permeability log from LWD NMR is static one and needs to be converted to dynamic one before using it for completion design and productivity estimation. Formation-pressure-while-drilling (FPWD) technology is designed to measure formation pressure from a small, predefined drawdown and buildup at certain formation depth. From this small drawdown and buildup, the formation mobility can also be estimated like in the interpretation of well-test data. Since the fluid entering FPWD tool during pretest is mud filtrate, the viscosity incorporated in pretest mobility is mud filtrate viscosity which is known. So, the permeability at certain depth can be estimated and it is dynamic one. With many pretests taken in a wellbore, many points of dynamic permeability are acquired. By considering the different depth of investigation and core analysis result, the static permeability log from LWD NMR can be calibrated by dynamic one from FPWD to make a continuous dynamic permeability log for completion design and productivity estimation. 3 wells data are used to demonstrate the efficacy of this methodology. Following proposed methodology, the estimated oil production rate matches the actual one in all 3 wells.