GB1359360A - Well logging - Google Patents

Abstract

1359360 Wells &c MARATHON OIL CO 20 Oct 1971 [27 Nov 1970] 48834/71 Heading E1F A well log is constructed during a well drilling operation using drilling fluid by testing an increment of the fluid as it enters the well and after it leaves the bit for each of a series of drill bit depths, by subtracting each reading obtained from testing each leaving increment from the reading from testing each entering increment to obtain a series of differences for each of the series of depths, by subtacting each difference from the preceding difference to obtain a series of changes of difference for a series of depths below an initial starting depth, and by plotting the differences and/or changes of difference against depth on a well chart. An indicator may be introduced into the drilling fluid and any physical characteristic of the fluid may be measured. A measure of the permeability of formation being drilled may be obtained by subtracting the volume of filtrate extracted from a sample of an entering increment from the volume of filtrate from a corresponding sample of the increment as it leaves the well.