STUDY ON MACRO AND MICRO MODELING ON SOLIDIFICATION PROCESS OF SHAPED CASTING

Facing the market economy and global challenge the development ofmanufacturing industry especially casting industry is critical to the national economy. To reformthe traditional casting industry by using computer technology is one of the hottest researchfrontiers studied by many researchers and engineers. Computer simulation of solidification processof shaped casting can assure the quality of casting, optimize the casting technology, shorten thelead time and therefore decrease the developing and manufacturing cost. Recently, numericalsimulation of mold-filling and solidification processes of shaped casting and prediction ofmicrostructure and property as well are extensively studied and put into application in many castingplants with many successful simulation cases.

Comparative studies on numerical sensitivity of different scenarios of enhanced oil recovery by water-alternating-gas(CO_(2))injection

Enhanced oil recovery by CO_(2) injection technology(CO_(2)-EOR)plays a crucial role in enhancing oil production and the permanent sequestration of anthropogenic CO_(2) in depleted oil reservoirs.However,the availability of CO_(2) in oil field locations and its mobility in contrast with reservoir fluids are prime challenges in CO_(2)-EOR.The cost of CO_(2) and its availability at the oil fields has prompted investigations on efficient injection of CO_(2) at the fields to achieve the best sweep efficiency possible.Injection strategies such as water-alternating-gas(WAG),simultaneous vertical and horizontal WAG,simultaneous water injection into the aquifer and vertical WAG,water and gas injection simultaneously but separately(SS-WAG),and water and gas injection simultaneously but not separately(SNS-WAG)play a significant role,as well as the purity of CO_(2).In this work,the significance of the above criteria was investigated indi-vidually and in combination.The coupled sequence of injection rate,soaking time,WAG ratio,and purity of injected CO_(2) for enhancement of oil production were delineated.A realistic reservoir simulation model conceptualizing the CO_(2)-EOR system with five spot injection patterns was developed by the company CMG.The history-matched model that was developed was used to investigate the sensitivity of the coupled effects to the criteria listed above on oil recovery.Numerical investigations quantitatively emphasized that purity and soaking time of CO_(2) have an inverse effect in the oil production rate and that SNS-WAG resulted in a better oil production rate than SS-WAG.