Asphaltene Clustering in A Black Oil Column Driven by Gas Addition, Explained via History Matching of Reservoir Charge
Westside Houston
Speaker:
Seminar Date: Aug 14 2025
Registration Opens: Jul 22 2025 - Aug 15 2025
Time: 11:30 AM - 01:00 PM (US CDT)
Admission/Registration Link: None
Donation Link: None
Meeting/Webinar Link: None
Contact: QinShan “Shan” Yang (VP Westside, SPWLA Houston Chapter)
Corresponding: vpwestside@spwla-houston.org
Fees: FREENOTES:
Speaker : Tarek S. Mohamed (SLB)
Date : Thursday, Aug 14th, 2025
Time : 11:30 am – 1:00 pm (US CDT)
Venue : SLB, 6350 West Sam Houston Parkway North, Houston, TX 77041
Admission : This activity will include a boxed lunch.
The seminar is sponsored by SLB so there
is no charge for registration,
However, you still need to register using
the applicable links below:
Parking Info : Guest parking is available free of charge. Upon arrival, please proceed to the front desk to check in
Please register by one day before the event to reserve lunch using the above provided link.
Contact : QinShan (Shan) Yang (SPWLA Houston VP Westside)
Corresponding : vpwestside@spwla-houston.org
ABSTRACT:
A tilted-sheet, well-connected reservoir in the deepwater Gulf of Mexico/America exhibits bimodal and complex fluid distributions. The acquired measurements of methane isotope, asphaltene concentration, and solution gas-oil ratio (GOR) indicate a diffusional gradient of solution gas and lack of equilibrium in the top half of the oil column, whereas the bottom half of the oil column shows quasi-equilibrium and well-mixed oil. This startling distribution gives rise to an asphaltene clustering trend in the bottom half of the oil column, leading to large oil viscosity and asphaltene gradients toward the base of the oil column. Our objective is to model the fluid mixing dynamics, over geologic time, of separate gas and oil charges and the impact of a significant GOR increase on asphaltene spatial distributions. For the first time, we simultaneously model the development and dynamics of both asphaltene and GOR distributions over geologic time leading to present-day, bimodal measured fluid realizations. Geochemical evaluation of acquired fluid samples shows a significant amount of biogenic gas throughout the entire oil column where methane isotopes indicate that 50% of the solution gas in the bottom half of the oil column is biogenic, and where the biogenic gas fraction increases at the top half of the column. Furthermore, GOR measurements indicate significant variations in solution gas at the top half of the column, increasing by 6000 scf/bbl over 130 ft of height. This gradient is successfully matched with the diffusion equation. On the other hand, the lower half of the column shows a small GOR gradient that is matched locally with the cubic equation of state (EoS). Asphaltene concentrations respond to the high GOR in the top half of the column as asphaltenes are expelled with great efficiency toward the bottom half of the column, forming asphaltene clusters. Asphaltene clusters remain due to both increased asphaltene concentration and increased solution gas. This process gives rise to a light-oil gradient of the asphaltenes in the top half, and a heavy-oil clustering gradient of asphaltenes in the bottom half of the column. Both gradients are not expected in a black-oil reservoir and are matched with corresponding models of Flory-Huggins-Zuo equation of state (FHZ EoS). The puzzling fluid distributions are explained and replicated by forward modeling of fluid mixing dynamic processes over geologic time: history matching of reservoir charge. Compositional reservoir simulation is used to model the addition of methane through a point source into an oil-saturated reservoir, resulting in the development of present-day GOR and asphaltene measurements.
BIOGRAPHY:
Tarek S. Mohamed (SLB) is an Interpretation Development Engineer and an Interdisciplinary Subsurface Scientist at SLB, working on various projects spanning reservoir engineering, petrophysics, and geophysics. He co-leads the development of the new direction of forward modeling reservoir fluid geodynamics (RFG) processes over geologic time using reservoir simulation, and history-matching reservoir charge as a new way to predict fluid spatial compositional distributions in untapped regions. Dr. Mohamed co-authored over 20 technical papers accepted by several organizations, including SPWLA, SPE, SEG, AAPG, and ACS, and published in peer-reviewed journals or presented at major energy conferences. His expertise includes reservoir numerical modeling and simulation, petrophysics and formation evaluation, data science and machine learning, reservoir characterization, and well-test analysis. He holds a PhD in Petroleum Engineering from the University of Texas at Austin, an MS in Petroleum Engineering and a Graduate Certificate in Data Science and Analytics from the University of Oklahoma, and a BS in Petroleum Engineering from Suez University. He received several technical awards and recognitions, including the 2025 SPWLA Young Professional Technical Achievement Award, as well as being selected as an SPWLA Global Distinguished Speaker for 2023-2024 and an SPWLA Regional Distinguished Speaker for North America for 2024-2025.