Introduction to geophysical well logging and flow testing

Abstract

Well logging is the practice of making a detailed record of the geologic formations penetrated by the well. The log may be either geological logs or geophysical logs. In geothermal, geophysical logging is done to identify location of fractures, the lithology and record the physical parameters like temperature and pressure. Important logs include temperature, pressure, gamma, neutron, cement bond log, calliper log, resistivity and directional surveying. When the well has recovered sufficiently, a flow test is conducted by flowing the well to evaluate the total flow rate, enthalpy and chemical characteristics of the discharged fluids. A common method used in flow testing is the lip pressure method (Grant et al., 1982). The well is discharged under different throttle conditions to get the characteristic curve to be used in selecting operating conditions for the turbines in the power plant.