Measurement While Drilling MWD

The use of measurement and logging while drilling has matured a great deal in the last 10 years.  The use of these tools that have been developed for the oil and gas industry for use in primarily sedimentary depositional environments must be investigated in light of the goals set for EGS systems.  Let us first define what is meant in this section by the terms, realizing that the line between these two areas continue to blur.

• Measurement While Drilling (MWD): Tools that measure downhole parameters of the bit interaction with the rock are MWD tool.  These measurements typically include vibration and shock, mudflow rate, direction and angle of the bit, weight on bit, torque on bit, and downhole pressure.
• Logging While Drilling (LWD): Tools that measure downhole formation parameters are LWD tools.  These include gamma ray, porosity, resistivity and many other formation properties.  The measurements fall into several categories that are discussed below.  The oldest and perhaps most fundamental formation measurements are spontaneous potential (SP) and gamma ray (GR).  Today one or both of these traces are used mostly for correlation between logs.  Electric or formation resistivity logs are another class of logs used in oil and gas logging.  Because of the long history of these logs, several varieties have evolved.  The electrical basis of this class of logs is to measure the conductivity or resistivity of the various geologic materials and fluids in them.  The resistivity of shales vs that of a clean sand set the limits for an ideal electric log.  The fluids in the formation also are reflected in this measurement as water is conductive when found in boreholes and oil is not.  The basic use of electric logs is to delineate bed boundaries and in combination with other logs to determine gas/oil/water contacts.  Yet another class of logs is density logs.  These logs are indicative of the formation density of the material in the well bore.  These logs require either a neutron or a gamma source, and actually measure gamma ray flux differences.  Porosity tools are another class of common logging tools.  These tools normally use chemically or now more common electrically generated neutron to estimate formation porosity.  Since these logs are normally calibrated in sandstone, limestone or dolomite care has to be taken when measurements are made in different rock types.  Finally in the last few years a number of specialty tools have evolved, these include specialized formation pressure testing tools which can be run while drilling, nuclear magnetic resonance tools, and pulsed neutron spectroscopy tools to list only the most popular.

Rationale for use

In recent years the cost of an average oil and gas hole has increased dramatically, part of this cost increase has been driven by the need to go after much deeper and more complicated reserves.  This increases the risk of failure of holes drilled into these reserves.  As a reaction to increased risk, the use of LWD and MWD technology and techniques has increased.  In the final analysis, the decision to use of LWD and MWD tools depends on managing risk.  The EGS program moves the art of geothermal drilling into a new region of risk, the evaluation of the LWD and MDW technologies must be undertaken to determine the applicability of these technologies to the particular risks faced in this new effort.  It is important to realize in the EGS model, in many cases we are not going to be setting our surface casing into igneous or metamorphic rock as we have in the past.  These deeper holes may look more like the classic oil and gas hole at the shallower depths, with this in mind we begin to examine the possible uses of the LWD and MWD technologies. 

The self-seeking gyroscope inclinometer produced by Vigor is one of the best products in the world, capable of measuring and recording for long periods of time in high-temperature and high-pressure environments. At present, Vigor's gyroscope inclinometer has been used in oilfield sites in Europe, North America, Africa, the Middle East and Asia and other regions, and Vigor's professional technical service team has also gone to the customer's site for on-site service, and the customer has highly praised the technology and products of the Vigor team, and looks forward to further cooperation with us. If you are interested in gyroscope, inclinometer or logging services, please do not hesitate to get in touch with the Vigor team to get the most professional technical support and the best quality service.

For more information, you can write to our mailbox info@vigorpetroleum.com & marketing@vigordrilling.com