Miscible Gas Injection and Asphaltene Flow Assurance Fluid Characterization: A Laboratory Case Study for a Black Oil Reservoir

Abstract

Miscible gas flooding is the most commonly used enhanced oil recovery (EOR) method. One of the most important experimental parameters for miscible gas injection is minimum miscibility pressure (MMP). Many times, the MMP of a system can be very high. Instead of raising the pressure to achieve miscibility, injection gas may be enriched with intermediate components. The enrichment level at which the gas-oil system becomes miscible is called minimum miscibility enrichment (MME). Regardless of the values of MMP and MME, gas injected into a reservoir will most likely induce asphaltene precipitation, which may potentially cause formation damage and reduce flow in the production tubing. In this paper, reservoir fluid from a Kuwait reservoir was analyzed to check for the feasibility of miscible gas injection. First, a series experiments were conducted to measure MMP with various gases using different techniques and MME testing with slimtube experiments. Moreover, the benefits, disadvantages, and applicability of each experimental method for EOR testing with gas injections were compared. Second, asphaltene precipitation upon gas injection was investigated in detail by measuring the precipitation onset conditions. Asphaltene precipitation onset was measured using a near infrared (NIR) light-scattering technique and a high-pressure microscope system to analyze the measured data. Finally, the asphaltene precipitation locus on a pressure-temperature (PT) diagram and the amount of precipitation were modeled for the reservoir fluid with different concentrations of injection gas. The modeling was carried out using a composition-based cubic equation-of-state approach. The experimental and modeling results indicated that an increase in concentration of injection gas appears to aggravate asphaltene precipitation.

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

“…The derived correlation also showed a good agreement for these larger n-alkanes. The correlation was compared with those of Moysan et al (1986) and Carroll and Mather (1995). As shown in Fig.…”

Prediction of Gas Injection Effect on Asphaltene Precipitation Onset Using the Cubic and Cubic-Plus-Association Equations of State

“…It has been shown in this work that the CPA, SRK, and SRK+HV models can successfully predict the gas (CO 2 , N 2 , hydrocarbon) injection effect after fitting the model parameters to experimental data of a single gas injection scenario. The temperature 33 and lines represent results from all the three models. Asphaltene amount in C 6+ fraction is 0.1 mol%.…”

“…The values of T c , P c , and ω are kept the same as considered in case of the SRK model. The self-associating energy (ε 33 /R) and volume (β 33 ) between asphaltene molecules are fixed to 3000 K and 0.05 (dimensionless), respectively. Due to the association, the solubility parameter of asphaltene is increased to 21.51 MPa 1/2 in case of the CPA model from 19 MPa 1/2 in case of the SRK model at 298 K and 1 atm.…”

High-Pressure Data and Modeling Results for Phase Behavior and Asphaltene Onsets of Gulf of Mexico Oil Mixed With Nitrogen

“…Many authors have studied asphaltene precipitation phenomena (Srivastava et al 1999;Jamaluddin et al 2002a, b;Buckley et al 2007;Lim et al 2008;Gonzalez et al 2012;Memon et al 2012). Gas injection will make the reservoir fluid swell, and will therefore help maintain the reservoir pressure and prolong the production rates.…”