Abstract
Pressure maintenance by waterflooding is a prominent recovery process in many of California oilfields. Majority of these turbidite sandstone reservoirs contain highly heterogeneous permeability profiles affected by alternation of sand shale sequences and the clay content. A typical signature of such heterogeneous profiles is often the existence of a high permeability streak serving as a "thief zone". Mechanical or chemical blocking of such layers on the injection or production side has been an objective of water flood management.
This paper presents a novel method for using a series of customized type curves to scrutinize the WOR characteristics plots of producing wells in stratified reservoirs. From a library of systematically generated performance plots for several combination of rock and fluid properties, and various architectural position of the high permeability zone, the actual data for a given well or a group of wells can be matched against various patterns to identify the degree of heterogeneity and the potential existence of a high permeability streak. With such a pattern recognition tool, opportunities to enhance the performance of individual wells or group of wells can be ascertained. Additionally, the impact of permeability modification by mechanical or deep chemical zonal isolation has also been studied. In brief, we have generated yardsticks by which the effectiveness of wellbore isolation or in-depth plugging of high permeability streak can be examined.
