NUMERICAL CALCULATION METHOD AND ITS APPLICATION OF THE SALT ROCK 3-AXIAL CREEPING

The salt formations will generation a nonuniform external squeeze stress when it is creeping and deforming, it can make the cases damaged. The salt formations depth of ZhongYuan Oilfield is from 50 to 200 meters. Statistical result showed that the location of damaged case in salt formations has reached 37% in total damaged case wells in Wen 13 oil field. In order to solve the problem from radical, the salt formations creeping velocity and displacement must be quantitative researched. Based on the salt rock 3-axial creeping experiment, established the salt formations deforming a stress-strain relationship, it also gived the theoretical formula and numerical calculation method, which used in specific calculation.The research adopts control-volume method, the creeping velocity and displacement and stress field and cases horizontal squeeze stress distribution rule of elevation oil reservoir profile of the salt formations are set up by simulation actual formation circumstances.Wen 13 east oil reservoir elevation profile the salt formations, creeping velocity is increasing with buried depth,thickness and dip angle; the creeping velocity of the salt formations, direction is upward as a rule or along the rock’s updip direction; the creeping direction of up covered rock and all round rock is down usually or along the rock’s downdip direction; creeping velocity of the salt formations near the fault place is greater than other place.The results are useful for adjust drilling parameter in creep formations and design the casing string and prevent the cases from damaging etc many field development engineering.