Study On Distribution And Potential-tapping Of Residual Oil In Reservoir Of Kexia Formation Located In Bai21 Well Field

The structure is simple and it has a serious heterogeneity reservoir for Kexia formation in Bai21 well field. After twenty years' development, it has been in medium-high water cut stage. Based on the serious heterogeneity, viewing from sedimentology and diagenesis point, it is considered that the internal cause of serious heterogeneity is the rock low compositional maturity and low textural maturity. Research of generous producing data indicates that well pattern thickening,forced injection and development aggravate reservoirs' heterogeneity. Relative high permeability zone play an important part on the small swept volume of water flooding and poor development.On the basis of oil saturation export model, we can calculate oil saturation of every well point during every substratum and draw the residual oil distribution scheme of every substratum by use of the actual producing data which can state more clearly about the seepage feature of entire reservoirs (including single well).The factors affecting the distribution of residual oil are so many, during all of the factors, heterogeneity of structure and reservoirs are internal factors, potential-tapping must focus on the residual oil in situ; development scheme and technique degree share the external type of role, the low degree for well pattern result in the imperfectness of injection and development, the pressure balance section between two oil wells usually become entrapment section of residual oil. If oil layer of injection well has changed greatly, there must be residual oil between two injection wells. Aimed at the distribution peculiarity of residual oil in serious heterogeneity reservoirs, the technique means for potential-tapping includes profile control and exclusion of water,adjust of injection and development,well pattern thickening, sometimes it may need compound technology.The features of this paper are mainly like followed: First, the reflection of reservoirs heterogeneity on production has been illustrated from three aspects which incorporates interference between layers,area difference of layer and inner interference of layer; Second, according to the material balance principle,basic differential equation of saturation area movement and Welge equation, we build the model of export oil saturation making use of actual producing data; Third, the potential-tapping of residual oil requires comprehensive application of many sorts of technique methods.