Resistivity measurements at the bit provide real-time formation evaluation before invasion
Real-time formation evaluation with today`s conventional horizontal drilling techniques is limited by the distance between the bit and resistivity measurements. Logging-while-drilling (LWD) sensors reach the formation long before wireline measurements, and so generally view it before wellbore degradation, but not before some invasion has occurred. Rapid invasion, called spurt, may mask true resistivity in some formations. The solution to this problem is to relocate logging measurements to the bit itself. A new LWD resistivity tool improves and simplifies formation evaluation by allowing geologists to visualize and log the formation around the wellbore before mud invasion or wellbore damage has occurred. The tool is normally run as a near-bit stabilizer on a rotary bottomhole assembly or just above the motor in a steerable assembly. It makes five formation evaluation resistivity measurements and an azimuthal gamma ray measurement. This paper reviews the performance of this tool.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 87501
- Journal Information:
- JPT, Journal of Petroleum Technology, Vol. 47, Issue 6; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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