Oil Production Gains for Mature Steamflooded Oil Fields Using Propane as a Steam Additive and a Novel Smart Horizontal Producer

摘要

We have conducted an experimental scaled model study to investigate the feasibility of two methods aimed at improving oil production from mature heavy oil fields. The first method involved the use of propane as a steam additive (propane:steam mass ratio of 4:100 was used in the study). The second involved the use of a novel well system consisting of a vertical injector and a smart horizontal producer. To minimize steam over-ride, the smart horizontal producer was divided into three sections, the section furthest from the injector being opened only after steam had broken through in the first two sections. The 16 in. x 16 in. x 5.6 in. physical model was scaled to present conditions in the San Ardo field in California and crude oil from the same field was used for the tests. The sides of the model consisted of 0.75 inch thick Teflon sheets to minimize heat loss, while the top and bottom consisted of 0.125 inch aluminum sheets to maximize heat conduction to the over- and under-burden. The physical model was placed in a pressure jacket containing nitrogen that provided an overburden differential pressure of about 20-40 psi during the runs. Superheated steam at 190–210°C was injected at 48 cm3/min (cold water equivalent) while maintaining the flowing pressures in the production wells at 50 psig. Liquid samples from each producer in the model were collected and treated to break emulsion and analyzed to determine water and oil volumes. Main results of the study may be summarized as follows. First, for the vertical well system, addition of propane accelerated oil production by 53% and increased ultimate oil recovery by 7% of original oil-in-place (OOIP) when compared to pure steam injection. Second, use of the smart horizontal well system increased ultimate oil recovery to 49% OOIP compared to that obtained with the vertical well system (42% OOIP).