| Abstrakt: |
The deep Paleogene resources in the eastern part of the South China Sea have huge potential, but weathering crust and coal seams are often developed. The instability risk of coal seam, especially the interbedded coal slime well wall is high, and complex situations occur frequently during drilling and completion, which greatly hindering the exploration and development process. Aiming at the technical problems of borehole stability of complex coal seam of Paleogene in an oilfield in the eastern South China Sea, the mechanism of borehole instability is discussed through the analysis of the microstructure and mechanical properties of coal rock, and the technical countermeasures of "multiple cooperative" borehole stability drilling fluid based on "physical plugging-chemical consolidation-hydration inhibition" are put forward. An anti-collapsing drilling fluid formula suitable for complex coal seam of Paleogene in an oilfield in the eastern South China Sea is constructed. The evaluation results show that the drilling fluid formula has good rheology, fluid loss, lubrication, plugging and inhibition, excellent anti-pollution performance, and can improve the compressive strength of complex coal seam samples to a certain extent, which is conducive to the stability of complex coal seam wall, in line with the needs of field drilling engineering. [ABSTRACT FROM AUTHOR] |
