THE DIPMETER USED TO RECOGNISE DEPOSITIONAL ENVIRONMENT

Abstract

Historically the major application of dipmeters has been towards the derivation of dip in formations penetrated by the borehole. This preoccupation has led to the development of computer programmes which ignore characteristic qualities of the dipmeter data. By computing numerical values for the qualities of (a) Dip pattern, (b) Nature of stratification, (c) Strata thickness, (d) Contrast between strata, (e) Formation hardness (hole diameter), (f) Hole eccentricity (directional homogeneity). (g) Resistivity anisotropy, each correlation can be classified as belonging to a definite numerical group.

Applying similar values to measured parameters of carefully documented geological sections representative of different sedimentary environments shows that similar numerical grouping can be recognised: hence, the environment should be revealed by the correlation grouping. Also, as horizontally-layered strata are infrequent in the geological cross-section, the dipmeter may not be an ideal tool for the measurement of regional dip.

If the dipmeter is accepted mainly as a tool for recognition of depositional environment and palaeocurrent direction, then a more appropriate correlation curve than of the micro-resistivity should be selected. The requirements of the geologist should spur the development of the necessary computer programmes and field equipment to improve resolution in the borehole, presentation of the dipmeter survey, and provide additional stratigraphic information.