The objective of a Flow Assurance study is to guarantee the flow from the reservoir to the end point consumers (through the surface facilities and pipelines). This is achieved by determining the phase boundaries and finding when waxes’ or asphaltenes’ deposition will occur (potential flow issues) or when hydrate will form and cause blockages with respect to changes in fluid properties (low GOR, wax and emulsion), reservoir properties (pressure and temperature) and environmental conditions (cold water, deep water).
Solid Deposition Studies
Texas OilTech Laboratories uses novel technologies for investigational flow assurance studies. These specialized studies include different processes which determine complete fluid composition and detailed property measurements. TOL uses a high-pressure PVT cell equipped with a laser transmittance device and a solid detection system (SDS) for flow assurance studies. The PVT cell is part of the Flow Assurance System (FLASS) Analyzer. The state-of-the-art FLASS Analyzer is mainly based on two independent systems to study the behavior of solid particles at reservoir conditions. First, the SDS which is based on near infrared light scattering principle, detects the presence of solid particles (200 nm) (i.e., asphaltene or wax) with high accuracy. Second, the high pressure microscope (HPM) simultaneously measures the particle size distribution and provides a visual of the particles (from 1µm).
Flow assurance needs specific laboratory procedures. The following testing package is available for flow assurance:
- SARA Analysis for Validity Checks
- Asphaltenes, and Waxes in Heavy Oil Studies
- Scaling and Corrosion Experiments and Mitigation
- Hydrate Formation
- Emulsion Analysis
Hydrate formation along the flowline reduces productivity. TOL investigates the phenomenon by measuring the fluid viscosity under variable temperature condition. This work is utilized as an attempt to balance between theory, project design, and flow assurance field practice.
Asphaltene/Wax Precipitation Test
Asphaltene deposition from reservoir fluids due to pressure depletion and temperature reduction can be a serious flow assurance problem. Flow Assurance analysis can be used to determine the pressure and temperature in which asphaltenes begin to form. The data generated from these studies is critical to the production process.
Wax Appearance Temperature
Wax molecules can precipitate out of the liquid oil to form solid wax particles, which can deposit on the cold internal pipe wall when the waxy crude oil is transported in a cold ambient, which is not only below the oil temperature but also below its Wax Appearance Temperature (WAT). Determining the WAT is useful in pipeline design and transportation protocol.