Formation Evaluation & Well Logging

What you'll learn

• Explain what formation evaluation must answer, plan a logging program for a well, read a log print and header, depth-match logs, and describe how logging tools with radioactive sources are regulated.
• Describe mud, mud cake and the invasion profile around a borehole, estimate formation temperature, correct mud resistivities with the Arps relation and judge hole effects from the caliper.
• Interpret the spontaneous potential and gamma ray logs, calculate shale volume by linear and nonlinear methods, find Rw from the static SP and use spectral gamma ray data.
• Explain how laterolog and induction tools measure resistivity, read invasion from curve separation and estimate Rt, Rxo and invasion diameter from array resistivity readings.
• Calculate density porosity with appropriate matrix and fluid densities, identify lithology with the photoelectric factor and recognize borehole and barite effects.
• Interpret neutron and sonic logs, use the neutron-density crossplot for porosity and lithology, detect and correct for gas, and calculate sonic porosity.
• Calculate water saturation with Archie's equation, explain the formation factor and the exponents m and n, and find m and Rw from Pickett plots and bulk volume water.
• Explain how clay affects log responses, distinguish total and effective porosity and apply the Simandoux, Indonesian, Waxman-Smits and dual-water saturation models.
• Evaluate carbonate and fractured reservoirs using multi-mineral methods, the secondary porosity index, pore-type-dependent cementation exponents and borehole images.
• Interpret NMR T2 distributions for bound fluid, free fluid and permeability, and use formation tester pressures to find fluid gradients, free water levels and depletion.
• Describe routine and special core analysis, apply Klinkenberg and capillary pressure conversions, and calibrate log interpretations with depth-matched core data.
• Carry out an integrated petrophysical evaluation with cutoffs, net pay, weighted averages and uncertainty, and provide inputs for volumetric estimates and development decisions.