My recent works - by Yan Gao       

                                   Chinese version (中文版)

  • SDVL technology                                 

Surface Drillstring Vibro-acoustic Logging (SDVL) is a novel logging technology that provides real time, on-line reporting of strata information, and horizontal reservior landing and guidance. SDVL monitors the hi-frequency low-energy vibration acoustic signals of an operating drill bit and determine the formation lithology and reservoir features from the vibration frequencies and their energy. It can be applied to various drilling activities to show formation lithological changes and their boundaries of depth location. Compared to conventional techniques, SDVL is less expensive, simple, easy to install and safer to operate.


  • What different from others

Surface Drillstring Vibro-acoustic Logging (SDVL) is very different from current technologies in market.


First, in compare with Measurement While Drilling (MWD), SDVL collects data at top of drillstring, and its equipment is installed on the surface and sensors like stethoscope of earth formation used for listening to the sounds produced within the lithological changes, while MWD is a downhole measurement technology. How to send downhole data to the surface is puzzle to the technology, so using mud pulse or telemetry drill pipe to help MWD transmission from bottom to up. Telemetry drill pipe is specially designed for conveying downhole sonic/acoustic logging data and MWD data to surface.


Well logging, also known as borehole logging, is the practice of making a detailed record (log) of the geologic formations penetrated by a borehole. Well logging is offline from drilling procedure and its measurement is after drill tripping trip, while an SDVL advantage is focus on measuring while drilling at top of drillstring and SDVL provides geologic information during drilling.


Mud logging is the process of collecting, analyzing and recording the meaningful solids, fluids, and gasses brought to the surface by the drilling fluid. Because of existing lagging time, analysis of the gross physical character of a rock or rock formation restricts current demand for fasting drilling and PDC bit application.


  • Advantages

More accurate reserve inventory

SDVL is very sensitive in identifying changes in reservoir lithology, especially thin pay zones, which are overlooked by the conventional logging techniques. This allows operators to have a better idea of where core samples should be obtained for analysis and improve the reserve estimation.


Indicate the horizontal landing point


The horizontal landing point is often located by trial and error. Using SDVL, operators will know when the drill-bit hits the desired zone. This saves time and reduces expenses.


More precise geological data

The SDVL provides precise, real time geological information. For example, if gamma ray data indicate that the drill-bit has reached the edge of the reservoir, usually the drill-bit is more than 3 or 10 meters ahead of the set location. 

More reliability data

The vibration frequency data were monitored with a wireless sensor network. A set of 1024-byte and 12-bit data can be obtained automatically at various depth intervals (from 0.1m trigger) using the winch count and hook load sensors. It has been applied to top-drive/table-rotary-drive, PDC/tri-cone bit, mud motor and assembly, and up to 5000m deep well.


  • Calibration

The SDVL system has an extensive database of reservoir lithology and vibration frequencies data for auto-identification system. However, for an unknown reservior, it is recommended to obtain pre-logging data for calibration purposes.