Improving Project Performance Utilizing Gravity Assisted Steamdrive (GASD) in Thick Heavy-Oil Reservoir

摘要

The Gravity Assisted Steam Drive (GASD) designed tornimproving production performance of thick heavy oil reservoirrnof S3, Wa 38, Liaohe Oil Field utilizing horizontal producerrnand associated vertical injectors. S3 is a thick extra-heavy oilrnreservoir with live oil viscosity of higher than 12,000mpa.srnand average thickness of 50m and permeability ofrn1000~2000×10-3μm2 in the upper layer and 300~500×10-3μm2rnin the bottom layer. From 1992 to 2003, it is developed byrnsteam huff and puff with the oil recovery of 24%. Since 2003,rnsteam drive pilot with 6 patterns was carried out to recoveryrnmore oil from S3 after steam huff and puff utilizing verticalrnproducers and injectors with 70×100m inverted 9-spot patternrnconfiguration. Up to now, the steam drive pilot sees a slowrnproduction response with lower production-injection ratiorn(about 0.8) and poor economics with higher SOR (nearly 10)rnand serious steam overriding owing to rhythm of reservoir andrnthickness. In order to improve the production performance ofrnsteam drive pilot, GASD is designed, with the horizontalrnproducer at the bottom and nearby the vertical injectors, torndecrease the steam overriding.rnThe paper will discuss the mechanisms of GASD, in whichrnsteam drive from the vertical injectors to horizontal producerrnis the main drive and gravity as the assisted drive, comparedrnwith the steam assisted gravity drainage (SAGD). The paperrnalso details the numerical simulation study of GASD, such asrnhorizontal well location, vertical injector spacing and distancernfrom horizontal producer, operational and start-up time andrnmanner of horizontal producer. Finally, the paper will brief thernimproving performance and economic profit of GASD, whichrndemonstrates the high productivity, good profit and thernfeasibility of applying horizontal wells with GASD in suchrnthick extra-heavy oil reservoir.