A Proposed Systematic Approach for Experimental Asphaltene Investigation: An Oil-Reservoir Case Study

Abstract

Summary Asphaltene precipitation and deposition are major flow-assurance issues that can reduce or completely stop the production of oil wells. To evaluate the severity of asphaltene problems in an oil reservoir, various laboratory tests should be planned. In this paper, a stepwise experimental approach is proposed to assess the asphaltene issue in oil reservoirs. Taking representative oil samples downhole is the first step to accurate experimental investigations. In case the sample does not represent the reservoir status correctly, all the laboratory data—even with accurate measurement—could be misleading. Then, reservoir-fluid characterization and saturate/aromatic/resin/asphaltene (SARA) analysis should be performed for primary evaluations and asphaltene-stability screening. Asphaltene-onset-pressure (AOP) measurement indicates the point at which asphaltene comes out of the solution. After that, assessment of asphaltene-precipitation potential depending on production scenarios (e.g., depletion or gas injection) at reservoir conditions should be performed. Finally, the effect of deposited asphaltene should be characterized in the presence of porous media in terms of deposition amount and its consequent permeability impairment. Eventually, this approach is used for an Iranian oil reservoir. This experimental approach, along with modeling and simulation of asphaltene precipitation and deposition, can be used as the best practice for assessing the asphaltene issue in oil reservoirs.