Near-Bit Propagation Resistivity for Reservoir Navigation (1994)

Near-Bit Propagation Resistivity for Reservoir Navigation W.H. Meyer; W.H. Meyer Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar Jian-Qun Wu; Jian-Qun Wu Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar D.T. Macune; D.T. Macune Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar P.R. Harvey P.R. Harvey Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 1994. Paper Number: SPE-28318-MS https://doi.org/10.2118/28318-MS Published: September 25 1994 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Meyer, W.H., Wu, Jian-Qun, Macune, D.T., and P.R. Harvey. "Near-Bit Propagation Resistivity for Reservoir Navigation." Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 1994. doi: https://doi.org/10.2118/28318-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractA new propagation resistivity tool has been designed and built with a measure point only 15 feet from the bit. Measurements of near-bit inclination and gamma ray are also provided. All of these measurements are in a package that includes a mud motor. The primary purpose of this tool is to provide a means for staying in a target formation during horizontal drilling. The propagation resistivity measurement of this reservoir navigation tool has the ability to see radially much deeper than focused resistivity devices. The radial direction is the direction of interest in horizontal drilling because the distance between adjacent beds is in the radial direction (relative to the tool). Devices which attempt to see beyond the end of the bit have limitations in a horizontal environment because the distance to the adjacent bed is very large in the direction of the borehole. In addition to the standard 2 MHz frequency, this new propagation resistivity tool has a second frequency of 400 kHz which has a much greater depth of investigation than the 2 MHz frequency. Measuring amplitude and phase at both frequencies produces 4 different depths of investigation at the same measure point. Modeling has shown that adjacent conductive beds can be detected as much as 12 feet away with the 2 MHz frequency and about 32 feet away at the lower frequency. These detection distances refer to the true vertical distance from the borehole to the adjacent bed, but the borehole may not intersect this bed for several hundred feet in horizontal drilling because the borehole is nearly parallel to the bed boundary. In addition, new state-of-the-art electronics and the use of a second transmitter have greatly improved the precision of the resistivity measurements. The result of these improvements is better accuracy in highly resistive formations. Therefore, this tool is able to provide both geosteering and a propagation resistivity measurement as accurate as the best wireline induction tools.IntroductionA new mud-motor integrated MWD tool has been designed, built and field tested. This tool includes gamma, inclination, and propagation resistivity measurements all much closer to the bit than had been previously possible when a mud motor was used. A diagram of the tool is shown in Figure 1. The basic principles of the propagation resistivity measurement can be found in Reference 1. The addition of a second transmitter (placed symmetrically with respect to the receiver pair) improves the accuracy of the tool. The purpose of the second transmitter is to cancel drift of the receiver antennas as a function of temperature and pressure. This, along with a new electronic design, has improved the accuracy of the measurements to less than 0.5 milli-mhos/m at 2 MHz. A second frequency (400 kHz) was added to help remove the dielectric effects and to increase the depth of investigation (in both vertical and horizontal logging applications). This second frequency also allows us to analyze the dielectric effects to improve the water saturation calculations in conditions of high Rw. The tool measures amplitude ratio and phase difference at 2 different frequencies resulting in 4 depths of investigation. Because there are more than 3 independent depths. The data can be used in an invasion correction chart (often called a tornado chart) to determine Rt, Rxo, and the depth of invasion.P. 263^ Keywords: propagation resistivity, frequency, well logging, upstream oil & gas, electronics, resistivity measurement, amplitude ratio, spe 28318, bit propagation resistivity, accuracy Subjects: Formation Evaluation & Management, Open hole/cased hole log analysis This content is only available via PDF. 1994. Society of Petroleum Engineers You can access this article if you purchase or spend a download.