Approach Of Steam Flooding Mechanisms&Application Of Deep Profile Control Technologies In Qi40Reservoir

The steam flooding reservoir, Qi40Block is located in the Huan Shu updip-stairs area,the Western Slope south, the Western Depression in Liaohe Rifted Basin. The targetformation of development is Lianhua oil reservoir with depth-625m~-1050m, oil density0.9686g/cm3, oil viscosity2639mPa.s at50℃under surface (gas free) conditions. TheReservoir, with an area of7.9km2and an OOIP (original oil in place) of3774x104t, is a typicalheavy oil reservoir with mid-deep burying and inter-bedding characteristics.The block is converted to steam flooding in2006, and reached its peak production at1931t/d from1280t/d at the initial conversion. In recent years, with the steam flooding goingon,82of139well groups in Qi40Block have stepped into the late flooding stage orbreakthrough stage, which is59.0%in total. At this stage the contradictions between layers orlevels increase, high-temperature steam channels seriously from one formation to another, theproduction decreases dramatically. The average sweep efficiency in65well groups in Qi40Block is59.0%vertically and57.5%horizontally according to the well temperature andstream absorption profile data. The fact of low production and high steam-oil ratio seriouslyaffect the steam flooding recovery and the economic profits.Combining with the reservoir rock and fluid properties, process conditions, andproduction data in the steam flooding block, Qi40, this paper applies numerical simulationtechnology to classify and evaluate the production performance, analyses the steam floodingeffect and sweep efficiency based on the consequences caused by the structuralcharacteristics, thief zone distribution and reservoir heterogeneity; and consequences onsteam chamber expansion caused by the heterogeneities of reservoir rock and fluid.This paper concludes the formation rhythm, structural dip, and reservoir rock propertiesas the three major factors which control the steam channeling in Qi40Block in accordancewith the evaluation of steam channeling. This conclusion is based on the study ondevelopment characteristics of3stages in steam flooding: thermal communication, steamflooding, and break through; the analysis of the consequences on steam sweep volume causedthe permeability variation coefficient, reservoir dip angle, perforation depth, horizontalpermeability anisotropy, thief zone thickness and stratification steam injection.This paper creates the practical technologies of deep channeling block with profilecontrol for the steam flooding in Qi40Block to improve the recovery factor by increasing thesteam sweep efficiency. The technologies are developed by the approach of deep profile control mechanisms, the evaluation of screening the high-temperature foaming additives, thesynthesis and evaluation of lignin surfactants, synthesis of modified lignosulfonate surfactant,evaluation of deep profile control of nitrogen foam system, and EOR testing study via aphysical model.