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Environmental Measurement While Drilling

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Resources

Technology
Summary Sheet

Technology
Summary Book

Technology
Deployment
Fact Sheets:
AR #1896
AR #1951
AR #2131

Innovative Technology
Summary Report
(pre-publication copy, dated 9/19/2002)

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Tech ID: 8

Project Overview
 The Environmental Measurement While Drilling (EMWD) sensor delivery system represents an innovative blending of new and existing technologies for obtaining real-time data during drilling. The objective of this project is to distinguish contaminated from non-contaminated areas in real time while drilling beneath a hazardous waste site. The downhole sensors are located behind the drill bit and linked by a high-speed data transmission system to a computer at the surface. As drilling is conducted, real-time data are collected on the nature and extent of contamination, thus enabling on-the-spot decisions regarding drilling and sampling strategies. The system provides real-time data on environmental conditions, drill bit location, and system health.

Technology Description
The EMWD system sensors include a gamma ray spectrometer (GRS) and an angular orientation sensor (3-axis magnetometer). The GRS consists of a sodium-iodide, thallium-activated crystal coupled to a photomultiplier tube (PMT). The GRS output feeds to a multichannel analyzer (MCA). The 256-channel gamma spectrum (0.1-1.6 MeV) data are transmitted to the surface via a signal conditioning and transmitter board. A full gamma spectrum is transmitted to the surface every 20 seconds. The drill bit location is determined by tracking the bit heading (azimuth), tool face (role), and inclination (tilt) using the angular orientation sensor. The readings from the GRS and the magnetometer are linked so that the position on contaminants is determined. Each of these readings is made every 2 seconds. Sampling speed from the analog channels can reach 100 kHz. The telemetry system is firmware programmable to easily support many different data formats and additional data channels. The data transmission format (digital frequency modulation (FM) bi-phase, 4,800 baud) provides excellent noise rejection for jumping the wireless connection between the rotating drill pipe and the stationary receiver. A Sandia National Laboratories (SNL)-designed receiver removes the FM carrier and buffers serial data to be used by a personal computer. A rechargeable battery pack supplies downhole instrumentation power for more than 18 hours of drilling. The battery pack remains uphole for easy maintenance and/or recharging.

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