Experiments were conducted to verify the feasibility of in situ upgrading of heavy crude oil by using a hydrogen donor (tetralin, C10H12) and an organometallic catalyst, Fe(CH3COCHCOCH3)3. Three cases were considered: pure steam injection; steam injection with tetralin; and steam injection with tetralin and catalyst. The cases were compared based on final recovery and properties of the produced oil.
The catalyst Fe(CH3COCHCOCH3)3 is highly soluble in tetralin. The concentration of the catalyst in tetralin was kept at 750 ppm. The experiments were conducted in a vertical injection cell. A mixture of sand, water, and Jobo oil, were thoroughly mixed prior to being tamped into the injection cell. For each of the two non pure steam injection cases two types of runs were conducted. In the first type of run, the tetralin or tetralin-catalyst solution was mixed with the sandmix before being tamped into the cell. In the second type of run, tetralin was injected as a slug ahead of steam injection. The Jobo oil used had an oil gravity of 12.4ºAPI and a viscosity of 7800 cp at 30ºC. All experimental parameters and conditions were kept the same for all cases. Produced fluids from the experiments were collected periodically through a series of separators. The cumulative produced oil for each run was then divided into two equal samples, and a series of analysis were carried out. These included measurements of viscosity and API gravity, and elemental analysis.
The experimental results may be summarizeda as follows. Addition of 5 wt% of tetralin increased oil recovery by 15% above that with pure steam injection. Premixing tetralin-catalyst solution with the sandmix yielded 20% higher oil recovery than the pure steam injection. When the tetralin-catalyst solution was injected as a slug, oil recovery was similar to that with injection of just tetralin. Acceleration in oil production was observed for all the runs but was more pronounced with the presence of the catalyst. Both the tetralin and tetralin-catalyst runs showed a potential application to improve recovery and oil quality. The improved oil quality may help reduce cost of oil upgrading on surface.