Annual Meeting of the American Institute of Mining, Metallurgical, and Petroleum Engineers, 24–28 February, New Orleans
This paper presents a new method for determining dip and strike of bedding planes observed in dipmeter survey data. A mathematical procedure has been developed for reducing these data to the dip and strike of formation penetrated by the drilling well. Computations are simplified and shortened with a Calculation Form which may be retained in the well files. The method is more accurate, faster, and easier to follow than any other method known to the author. The only requirements are a slide rule and a knowledge of elementary trigonometric functions.
Of great importance to the engineer and geologist is a knowledge of the dip and strike of formations penetrated by the drilling bit. The solution of this problem may be dependent on a dipmeter survey, particularly in wildcat wells and in wells being drilled in areas of extreme diastrophism where surface methods are inaccurate. A difficult problem arises in the calculation of true dip and strike from dipmeter survey data.
Various methods of interpreting dipmeter data have been presented in the literature. They include usage of a mechanical reader, and application of numerous graphical techniques requiring stereographic nets and charts. The limitations of these methods become apparent when they are put into practice. This paper presents an analytical method of treating dipmeter data which is believed simpler, faster and more accurate than any of the methods now in general use.
The dipmeter device employs three electrode arms equally spaced along the circumference of the borehole. The electrodes are pressed against the wall of the well to insure adequate electrical contact with the rock formations being studied. Either SP, resistivity or microlog electrode arrangements are used to make continuous measurements of properties of the stratigraphic column at each of the three are position. the various factors involved in obtaining these data are well-covered in existing literature, and will not be elaborated upon in this paper.