Research On Key Techniques Of Direct Reading Downhole Pressure Gauge

The change of the formation pressure, which describes the reservoir characteristics,measured through the downhole pressure gauge is one of the important well-testingtechniques. With the development of the oilfield entering the later period, the acquisitionof the downhole layer pressure data is of great significant. Based on the originalproduction of single probe pressure gauge, this paper develops a double probe downholepressure gauge with functions of direct-reading and layered.First, the development of the electronic pressure gauge at home and abroad isintroduced and the downhole pressure gauge overall scheme is determined in this paper.Second, this paper studies the two key technologies of pressure gauge which aredownhole data transmission technology and measurement data processing algorithms. Tosolve the problem of the digital coding for the data transmission of long-disturbanceunderground, the Manchester coding in the serial port is implemented. This paper adoptstwo wire system transmitter current signal transmission principles so the downhole unitpower supply and data transmission technology are implemented in a single core cable,and the data transmission distance is up to5000meters. By cubic spline interpolationalgorithm, the pressure gauge designed in this paper not only optimizes the calibrationdata points but also meets the pressure measurement precision of the under widetemperature range. Then, the software and hardware of the downhole unit and inoue ofthe developed pressure gauge is explained and the upper machine playback softwarefunctions and implementation are introduced. Finally, the pressure gauge test and testplatform are established. Contrasted with the field test data, the application verification isbuilt. The calibration precision of the original pressure gauge using least square methodand of the pressure gauge developed by us is compared and analyzed.The experimental result shows that the pressure gauge developed by us can meet theneeds of long distance data communication and the pressure gauge adopting the dataprocessing algorithm reaches0.02%pressure measuring accuracy. The result reaches theaim of developing the pressure gauge.