ABSTRACT
A unique experiment design is proposed to study the asphaltene precipitation caused by multiple contact processes during gas injection. The newly proposed experiment quantified the asphaltene precipitation at different methane contact steps. Twenty times methane contacts and corresponding asphaltene precipitation states are measured using a light scattering setup under reservoir condition. The amount of the asphaltene precipitation, the composition changes, and the physical properties changes are measured for the 20 times methane contacts. After verifying the asphaltene precipitation in the static experiments, the formation damage caused by the asphaltene precipitation is studied by core flooding tests for three different permeability cases. We found that the primary asphaltene precipitation mechanism in the multiple contact process during methane injection is not the composition change caused by methane extraction. The methane-induced asphaltene stability loss during the multiple contact process is vital. The size and the structure of asphaltene precipitation particles in the crude oil change with the methane contacts. We found that the mechanism of permeability reduction caused by asphaltene precipitation is different depending on the porous media pore throat size and the asphaltene precipitation particle size. Under our experimental condition, the asphaltene precipitation acts as a conformance control method, leading to well-distance optimization considerations in field applications.
