Abstract: A method of dipmeter processing fits a thickness conserving mathematical model to a folded or faulted subsurface sedimentary geological structure, and may be used with vertical as well as nonvertical or deviated boreholes. An initial estimate of the geometry of the structure is made and then used to generate a theoretical dip profile for the model. The dip profile is compared to an actual dip profile recorded in a borehole drilled in the structure. The estimates are modified by an iterated process until satisfactory concordance is obtained between the theoretical dip profile and actual dip profile. The iterated result gives geometric parameters which accurately model the structure. The model is graphically displayed to represent the structure. The model allows the prediction of dip configurations along any other borehole to be drilled in the structure.

Abstract: A method as disclosed of assisting in the determination of the existence of conical folding of the geological formation utilizing an existing dipmeter survey obtained through a wellbore penetrating the geological formation. Estimates of plunge and aperture of the geological formation, as well as the position of the wellbore with respect to the geologic formation are made. These estimates are utilized to generate a synthetic dip plot representative of conical folding. The synthetic dip plot is compared to the existing dipmeter survey, and one or more of the estimates are varied to obtain a final synthetic dip plot that has the highest correlation of the dipmeter survey, thereby providing an assistance in the determination of existence of conical folding of the geological formation.

Abstract: A dipmeter signal processing method and system are disclosed, wherein portions of at least three are matched, utilizing correlation intervals, to derive a plurality of possible offsets. For each of the offsets, the spatial coordinates are defined of an associated vector parallel to an implicit bedding plane. The coordinates are utilized to combine nonparallel vectors to generate a plurality of dips. The dips that substantially repeat for a given depth or repeat from one depth level to the next within a given depth zone are retained to retain a single dip for each depth. A display is then outputted of each dip at each depth.

Abstract: In order to determine dips of subsurface formations more reliably, a dipmeter tool with three or more transducers, spaced circumferentially around the borehole wall, is used and the transducer outputs are correlated in a novel way to provide redundant indications of displacements between the depths at which respective transducers intercept a given layer. These redundant displacements are processed to single out at each given level only those displacement pairs which result in the most consistent dips over several mutually overlapping depth intervals called zones. Consistency is established in each zone without regard to a neighboring zone, to avoid any long range bias.

Abstract: Disclosed is a well logging system using the output of a dipmeter tool, preferably a three or more trace tool, to produce a map showing at least one or more of the following characteristics of the earth formations surrounding a borehole: the location of a depth zone in which the formation dips are mutually consistent within defined criteria, the structural dip within a zone, the formation dips within a zone rotated to account for the shown structural dip of the zone, the confidence limits of the magnitude and azimuth of a shown structural dip and an azimuth frequency polar histogram of the dips within a zone. In addition, the system identifies sedimentary patterns within a zone, such as blue and red patterns and shows their nature and characteristics.

Abstract: Illustrative embodiments of the present invention include methods and apparatus for processing measurements indicative of the dip and azimuth of formation features at various depths in a borehole to produce three-dimensional representations of the formation features. These three-dimensional representations may be in the form of two-dimensional presentations of apparent dip traces for various depths in one or more planes. The apparent dips may be varied with distance from the borehole in accordance with information derived from dips above and below a selected dip. The three-dimensional representations may also take the form of a contour map of a formation surface around the borehold which represents a three-dimensional structural model derived from dips above and below the contoured formation surface.Dip and azimuth variations over a given interval are used to define a family of surfaces in a three-dimensional reference system.

Abstract: Illustrative embodiments of the present invention include methods and apparatus for processing geophysical signals derived from sources located at different positions in a borehole to obtain displacements which are then combined to determine the relative position of formation characteristics. The geophysical signals are correlated by pairs using substantially overlapping correlation intervals to obtain sequences of displacements for each pair. Displacements from each sequence are combined in possible corresponding relationships and classified in an angular classification system relative to the position of the sources of the correlated signals. Displacements from overlapping sequences are also combined and classified, and an analysis is then performed on the classified combinations to determine which combinations are valid.Invalid displacements, for example, are sometimes produced by the failure of the borehole tool used to derive the signals to remain in the preferred position in deviated holes.

Abstract: An improved dipmeter plot of the attitudes of earth formation features in the vicinity of a borehole is produced by using a dipmeter which has at least four transducers urged into contact with the borehole wall, detecting which (if any) of the transducers fail to achieve satisfactory transducer-wall contact and producing the sought dipmeter plot from the transducer outputs less the signal from any transducer failing to achieve satisfactory transducer-wall contact. The occurrences of unsatisfactory transducer-wall contact are detected by seeking to find inconsistencies between the outputs of the individual transducers of the dipmeter tool, and additionally between such outputs and the diameter of the borehole at the relevant depth. The process is speeded up by checking first the transducer which is closest to the borehole top at the relevant time.