THREE-DIMENSIONAL ANALYSIS ON HOW MUD WEIGHT AFFECTS THE GYPSUM-SALT BED CREEP

The design of proper drilling fluid density in the hole, combining with the analysis on the creep tendency of salt bed is the key for successful drilling in the gypsum-salt formation. Based on the study of salt bed mechanics, the phenomena of hole instability in the gypsum-salt bed, especially in the deeper formation caused by unsuitable mud density is investigated, and a gypsum-salt bed creeping-pressure calculating model is proposed therefore. Well Sha-24 in North Tarim Basin is taken as an example, and the gypsum-salt creeping pressure in this well is analyzed. The result shows that this model coincides with the real condition in the well.