Research On The Waterflow Predominant Channels In Sandstone Reservoir

For most of the continental sandstone reservoir,the permeability is high,the degree of consolidation is rather weak and the heterogeneity is severe.After a long-term conduction of water injection,the waterflow predominant channels are easily developed in the area with relatively high permeability,which makes injected water inefficient or even ineffective and poses a threat to oil fields' development expense.It has a bad impact on oilfields' economic benefits when the oil price is low.Therefore,the investigation on the waterflow predominant channel is of great significance for oilfield development.This paper is based on the S3 fault blocks in D oilfield,the formation mechanism of waterflow predominant channels in the two main oil layers is first analyzed from the aspects of geology(sedimentary facies,clay mineral,degree of consolidation,reservoir heterogeneity and oil viscosity)and post-production.In addition,the conceptual models of heterogeneity of two main oil layers are established using Eclipse,focusing on the inter-layer,intra-layer and planar heterogeneity dependences of waterflow predominant channels formation.Secondly,in the qualitative characterization of the waterflow predominant channels,the characteristics of porosity,permeability,production rate,bottomhole pressure,injection profile and logging curves are analyzed synthetically to study how waterflow predominant channels influence the production performance.At the same time,the site data is utilized for mapping out the planar and cross-sectional distribution profiles of the waterflow predominant channels of the main oil layer.Finally,in terms of quantitative representation,three methods proposed by predecessors are citied,that are,correlation coefficient-theoretical water-oil ratio estimation method,the inter-well tracer monitoring time estimation method,and the excess water-comprehensive evaluation estimation method.These three methods are applied in the same injection well group of the S3 fault blocks,during which the water injection and production rate are reasonably split in the calculation of parameters of waterflow predominant channels,e.g.average pore-throat radius and permeability,and the final results from three methods are compared comprehensively with the actual results measured by oilfield,with error analysis taken into account and pros and cons of each method summed up.In this paper,theoretical research on waterflow predominant channels is applied to applications,which gives guiding instructions on the control and later treatment of these channels.