Quality control system and engineering practice of medium-deep core drilling in Qiangtang Basin， Xizang

Abstract:

In response to the special conditions in the Qiangtang Basin， Xizang， such as high altitude， severe cold and oxygen deficiency， prone to loss and diameter reduction in the interbedded potash-limestone formations， and ecologically sensitive plateau environments， a full-process quality control system of "pre-drilling planning， strict in-process control， verification and archiving， closed-loop improvement" was established based on the 901.50 m medium-deep core drilling project of QS6 drilling hole. The control indicators and technical measures were established from seven dimensions， including core recovery， borehole deviation， depth accuracy， simple hydrological observation， raw data， hole sealing operations， and quality supervision. The engineering practice shows that the core recovery rate of this drilling hole reached 98.44%， the maximum hole inclination was 2.0°， the depth calibration error was ≤2 cm， and no in-hole accidents or mechanical failures happened， in addition， the raw data were standardized， the drilling hole sealing met the quality requirements and all indicators surpassed the design specifications and the requirements of the "Geological Core Drilling Code". The resulting quality control model for medium-deep drilling in the plateau can effectively ensure the reliability of drilling results under complex strata conditions， providing technical support for mineral survey and evaluation drilling in the Qinghai-Xizang Plateau.