Laboratory Tests for Heavy Oil Recovery (HW+MEOR)
Laboratory tests for heavy oil recovery involve a systematic process starting with core selection and material characterization (rock, crude, brine). These steps establish baseline properties like porosity and viscosity. Subsequent phases focus on preparing initial reservoir conditions and executing specialized rock-fluid interaction tests, culminating in core flooding experiments to evaluate enhanced oil recovery (EOR) mechanisms.
Key Takeaways
Core samples must be meticulously selected and registered following API RP 42 standards.
Comprehensive characterization of rock, crude oil, and brine is essential before testing.
Initial core preparation involves cleaning, saturation with brine, and aging to restore wettability.
EOR evaluation relies on advanced tests like spontaneous imbibition and Core Flooding experiments.
How are core samples selected and registered for heavy oil laboratory tests?
The initial phase focuses on obtaining and documenting the necessary rock samples, specifically carbonate and sandstone cores, with the primary objective of securing the required core plugs. This involves a step-by-step procedure to obtain core coins and characterize each sample individually to ensure suitability for testing. Crucially, all samples must undergo rigorous registration and chain of custody procedures, typically adhering to standards like API RP 42, ensuring traceability and integrity throughout the entire laboratory testing process.
- Objective: Obtain the necessary core plugs for testing.
- Procedure: Obtain core coins and perform individual sample characterization.
- Documentation: Implement registration and Chain of Custody according to API RP 42 guidelines.
What materials require characterization before conducting heavy oil recovery experiments?
Before any displacement tests, it is mandatory to characterize the base materials: the rock cores, the crude oil, and the brine solution. Rock characterization establishes petrophysical properties, while crude oil characterization defines its physical-chemical behavior under reservoir conditions. The brine, typically prepared as a 2% weight/weight solution or based on specific design, must also be analyzed to ensure its properties accurately reflect the formation water, guaranteeing reliable experimental results.
- Rock Characterization Properties:
- Measure absolute and effective porosity.
- Determine permeability using gas or liquid.
- Calculate pore volume (PV) and density.
- Capture images and texture (CT scan if applicable).
- Crude Characterization Properties:
- Determine density.
- Measure viscosity and rheology (curves vs. Temperature and Shear Rate).
- Analyze SARA fraction.
- Measure Acidity (Total Acid Number - TAN).
- Brine Characterization Properties:
- Preparation: Calculate salts (weight/weight), homogenize, and filter.
- Properties to Record: Conductivity, pH, and salinity (ppm).
How are initial reservoir conditions prepared in the laboratory core samples?
Preparing initial conditions involves meticulously treating the core samples to simulate the reservoir state before EOR injection. This starts with cleaning and drying the cores if necessary. Next, the cores are saturated with brine, defining the initial water saturation (Sw), through slow injection under vacuum until no bubbles remain. Subsequently, the core is saturated with crude oil to restore the target oil saturation (So) via imbibition or displacement. The final crucial step is aging the core for 48 to 168 hours at reservoir temperature to stabilize wettability.
- Clean and dry cores if required.
- Saturate with brine: Slow injection under vacuum until bubble absence (to define initial Sw).
- Saturate with crude: Injection via imbibition or displacement (to restore target So).
- Age the core: Duration of 48–168 hours at reservoir temperature for wettability stabilization.
What specialized tests evaluate rock-fluid interaction in heavy oil systems?
Specialized tests are essential to understand how injected fluids interact with the rock and crude oil, focusing on wettability and fluid dynamics. Spontaneous imbibition tests measure the volume and rate of fluid absorption, comparing phases like 2% brine, hot water, and alkaline solutions (SAO). Wettability is quantified using the contact angle, measured by forming a micro-droplet of crude on a saturated slide. Interfacial Tension (IFT) is measured using methods like the Hanging Drop or Spinning Drop, while emulsion characterization assesses stability, droplet size, and rheology, providing critical data for EOR design.
- Spontaneous Imbibition Objective: Measure volume and rate of absorption.
- Imbibition Phases Compared: 2% Brine, Hot Water (define T), and Alkaline Solutions (SAO).
- Imbibition Temporal Registration: Measure mass/volume at 1m, 5m, 15m, 1h, 6h, 24h intervals.
- Contact Angle Method: Goniómeter with submerged cell (HPHT if applicable).
- Contact Angle Procedure: Form a crude micro-droplet on a slide saturated in the aqueous phase; measure the angle 3-5 times.
- Contact Angle Interpretation: Aqueous if angle < 70°; Oleophilic if angle > 110°.
- Interfacial Tension (IFT) Methods: Hanging Drop (HPHT) or Spinning Drop.
- Emulsion Characterization Parameters: Stability, Droplet Size, and Rheology.
How are advanced fluid properties and displacement efficiency measured for EOR?
Advanced testing focuses on fluid flow behavior and displacement efficiency under simulated reservoir conditions. Viscosity and rheology measurements are performed using an HPHT rheometer on samples like crude, emulsions, or crude mixed with alkaline solutions (SAO). Measurements are taken across various shear rates and temperatures (40, 60, 80 °C) and analyzed using rheological models like Power-law or Bingham. The ultimate evaluation is the Core Flooding experiment, which simulates displacement in a core holder under reservoir pressure and temperature, using a defined sequence to assess recovery factors for different EOR agents.
- Rheometer Sample Preparation: Crude, Emulsions, Crude + SAO.
- Rheometer Measurement: Measure at various Shear Rates (0.1 to 100 s⁻¹) and vary Temperature (40, 60, 80 °C).
- Rheometer Analysis: Fit data to rheological models (Power-law, Bingham).
- Core Flooding Test Conditions: Conduct the assay at Pressure and Temperature (Colholder/Core Holder).
- Core Flooding Displacement Sequence: Hot Water → SAO Slug → Water Drive.
What quality control and documentation standards are required for heavy oil lab tests?
Transversal control ensures the reliability and safety of all laboratory procedures, which is critical for generating trustworthy data. Quality control mandates the use of repetitions and detailed records for all measurements to ensure data accuracy and reproducibility. Safety protocols are paramount, requiring the strict use of Personal Protective Equipment (PPE) and safe handling procedures for chemicals and crude oil. Furthermore, all procedures must be structured and detailed, including key components such as the objective, required equipment, step-by-step instructions, data registration methods, and specific safety considerations for each test.
- Quality Control: Ensure repetitions and detailed records are maintained.
- Safety: Mandate the use of PPE and safe handling of chemicals/crude oil.
- Detailed Procedure Structure Key Components: Objective, Equipment, Steps, Registration, and Safety.
Frequently Asked Questions
Why is core aging necessary before displacement tests?
Core aging is essential to stabilize the rock's wettability, simulating the long-term interaction between the reservoir rock and the crude oil. This process typically lasts 48 to 168 hours at reservoir temperature to achieve representative conditions.
What is the primary purpose of the spontaneous imbibition test?
The spontaneous imbibition test measures the natural tendency of a fluid (like brine or EOR solution) to be absorbed by the rock, displacing oil. It quantifies the volume and rate of absorption over specific time intervals.
What properties are characterized for the crude oil in these tests?
Crude oil characterization focuses on density, viscosity, rheology (vs. T and shear rate), SARA fraction analysis, and acidity (Total Acid Number or TAN). These define the oil's flow behavior and chemical reactivity.
Related Mind Maps
View AllNo Related Mind Maps Found
We couldn't find any related mind maps at the moment. Check back later or explore our other content.
Explore Mind Maps
