Overview
ISO 13503-4:2006 - Petroleum and natural gas industries - Completion fluids and materials - Part 4 - defines a standard, repeatable static fluid-loss (leakoff) test for stimulation and gravel-pack completion fluids. The standard provides a consistent laboratory procedure to measure fluid loss (filtrate volume) into porous media under static conditions and to calculate leakoff and fluid‑loss coefficients used in well completion engineering. Note: the procedure excludes fluids that react with porous media.
Key topics and technical requirements
- Scope & limitations
- Measures leakoff of stimulation fluids and gravel-pack fluids under static conditions.
- Excludes fluids that chemically react with the porous medium or instrument surfaces.
- Measurement precision
- Temperature precision: ±1 °C (±2 °F); other quantitative measurements: ±2% unless specified.
- Fluid preparation & documentation
- Full traceable record required: base fluid, pre-treatment, mixing order/time/speeds, components and amounts, aging, test temperature and pH.
- Minimize air entrainment during preparation.
- Apparatus & limits
- Typical static fluid-loss cells (examples shown for 175 ml and 500 ml capacities).
- Cells must accept filter paper, natural core or synthetic core, and include a back‑pressure receiver when test temperature exceeds filtrate boiling point.
- Minimum operating limits: ≥ 10 342 kPa (1 500 psi) and 121 °C (250 °F).
- Core/filter media
- Preferred core: formation-like permeability/porosity; standard core plug 2.54 cm × 2.54 cm (1.0 in × 1.0 in).
- Option to use pre‑saturated ceramic disks or filter‑paper assemblies (e.g., three 8 µm cellulosic papers over a 38 µm screen).
- Operational procedure
- Apply constant pressure (typical example: 6 895 kPa (1 000 psi) above back pressure), reach test temperature, optionally shut‑in, then collect filtrate at typical intervals: 1, 2, 4, 9, 16, 25, 36 minutes.
- Calculations & interpretation
- Plot filtrate volume vs time: linear behavior indicates viscosity‑controlled leakoff; non‑linear behavior suggests wall‑building (square‑root‑of‑time).
- Example equation: filtrate viscosity µ = k·A·ΔP / (Q·L) (variables: permeability k, area A, pressure ΔP, flow Q, length L).
- Provides methods to derive viscosity‑controlled fluid‑loss coefficient and wall‑building coefficient.
Applications and users
- Practical uses:
- Designing and optimizing fracturing and gravel‑packing operations.
- Selecting or formulating completion fluids with controlled leakoff and filter‑cake behavior.
- Quality control and performance comparison of stimulation and gravel‑pack fluids.
- Typical users:
- Completion and reservoir engineers
- Laboratory technicians in oilfield service companies
- Completion fluid formulators and proppant suppliers
- Standards bodies and regulatory testing labs
Related standards
- ISO 13503 series (Completion fluids and materials):
- Part 1: Viscous properties measurement
- Part 2: Proppant properties
- Part 3: Testing of heavy brines
- Part 5: Long-term proppant conductivity
Keywords: ISO 13503-4:2006, static fluid-loss test, leakoff measurement, completion fluids, gravel-pack fluids, stimulation fluids, filtrate viscosity, fluid-loss coefficient, filter cake, spurt loss.
Open preview (PDF)Petroleum and natural gas industries — Completion fluids and materials — Part 4: Procedure for measuring stimulation and gravel-pack fluid leakoff under static conditions
