OIL-BASED MUD IMAGING TOOL GENERATES HIGH QUALITYBOREHOLE IMAGES IN CHALLENGING FORMATION ANDBOREHOLE CONDITION, INCLUDING THIN BEDS, LOW RESISTIVEFORMATIONS, AND SHALES

摘要

Electrical imaging tools provide detailed informationthat can be very helpful in determining the structural,stratigraphic, and petrophysical properties of areservoir. In water-based mud (WBM) environments,electrical imaging has been available for almost 20years; but in oil-based mud (OBM) environments, goodquality electrical images were not obtained untilrecently. After several years of research anddevelopment, Halliburton successfully completed thedevelopment of an OBM imaging service: the Oil MudReservoir Imager (OMRI?) tool. The OMRI? tool isdesigned to acquire resistivity-based images offormations drilled with all types of non-conductivemud. A sensor predicated on capacitive coupling isused to overcome the insulating properties of the mudand to permit current flow in the formation.The sensor has been optimized for high verticalresolution and minimal standoff effects. The depth ofinvestigation is approximately 3.75 in. Log dataindicates good image quality with approximately 1 inchvertical resolution. The OMRI tool generates an imageof the formation resistivity based upon the response of36 micro-resistivity button pairs distributed among sixpads. The pads are mounted on independent armsarranged in two groups of three. The six arms act asindependent calipers to generate a more accurateborehole shape, and the micro-resistivity pads articulateboth horizontally and vertically for superior formationcontact in rugose borehole conditions. The relativeposition of the tool sensors is provided by a tri-axialaccelerometer and magnetometer. Proprietary signalconditioning methods further enhance the basicmeasurement to produce high fidelity images across thefull spectrum of “hard” and “soft” formations.The OMRI tool was successfully tested in a variety ofdepositional environments. Two prototype tools wereevaluated over thousands of feet of images. Afterseveral system improvements, the OMRI productquality exceeded design criteria and commercializationwas initiated. By the end of 2007 more than 20 toolshad been deployed.