Laboratory Tests Conducted to Perforate and Displace Viscous Oil from Saturated Formation Core to Help Optimize Steam Flood Completion

Abstract

Abstract API 19B Section 4 Flow Laboratory tests were conductedto test and optimizethe perforation strategy of wells in a shallow, viscous oil reservoir. Cored sand formation samples sealed inaluminum tubes wereremovedwith care and prepared to allow stressing for simulated perforation and displacement testing. The first challengewas to extract the viscous crude oil-saturated, unconsolidated cores taken from the zone of interestandpermittheir use with minimal disturbance. Once the cores were prepared such that stress and pore pressure could be appliedin an API RP 19B Section 4 configuration, shaped-charge perforators were shot to determine penetration depth and casing-entrance hole size. The central parameter investigated was casing-hole size, which regulates the flow-velocity/drawdown-pressure relationship important for sand control. The effectof solvent versus heat displacement of the viscous crude oil was also observed. Tests using heat to assess its effectiveness on promoting crude oil flow of a specific composition throughits associated sand causedminimal sand movement. The focus began with the perforation behavior in the stressed, viscous crude oil-saturated sand, followed by the flow of viscous crude oil through the sand, and then finally on how viscous crude oil-flow behavior was affected by viscosity reduction with heat. Results demonstratedthat even the smaller-shaped charges were capable of sufficient penetration, and the primary attribute was the resulting casing-entrance hole diameter. The desired hole size in a specific shots-per-foot perforator is a compromise betweenoptimal steam delivery for uniform injection across the targeted sand body and the maximum hole size for optimal production while minimizing sand production. When this abstract was written, multiple wells had been perforated and are currently under field evaluation and data gathering, which will be compared to laboratory findings. This paper includes discussions on the testing process used and the effect of perforating the viscous crude oil sand. Additionally, it offers insight into the effects of increasing the temperature of the viscous crude oil and selecting a perforating strategy.