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D4520-18 – Standard Test Method Technical Guide
📐 Overview and Scope
This practice, designated D4520-18, provides a procedure for conducting on-site core flood tests to determine the filtration and chemical treatment requirements for subsurface injection of water. It is applicable to water disposal, secondary recovery, and enhanced oil recovery projects, covering injection waters with all ranges of total dissolved solids contents. The values stated in SI units are to be regarded as standard, with inch-pound units provided for information only.
The standard emphasizes that it does not address all safety concerns, and it is the responsibility of the user to establish appropriate safety, health, and environmental practices. This international standard was developed in accordance with internationally recognized principles on standardization.
⚙️ Test Procedure and Applications
The practice involves conducting on-site core flood tests using test cores cut from full-core samples recovered from the formation into which water is injected. The tests help determine the maximum suspended solids size allowed in injection water to minimize formation plugging, known as the filtration requirement. The procedure references several ASTM and API standards for methodology, including D653 for soil and rock terminology, D1129 for water terminology, D2434 for permeability of granular soils, D4404 for pore volume distribution, API RP27 for permeability determination, and API RP40 for core-analysis procedures.
Key aspects include measuring permeability, pore volume, porosity, and understanding rock-water interactions, which can cause precipitation, swelling, or release of fines within the rock.
⚠️ Safety Note: Users of this standard must establish appropriate safety, health, and environmental practices. The standard does not address all safety concerns, so regulatory limitations should be determined prior to use.
📊 Key Terminology and Definitions
| 🟦 Term | 📏 Definition |
|---|---|
| Filtration Requirement | The maximum suspended solids size (in micrometres) allowed in injection water to minimize formation plugging. |
| Test Core | A sample cut from a full-core recovered from the formation into which water is injected. |
| Permeability | The capacity of a rock or other porous medium to conduct liquid or gas; measured as the proportionality constant between flow velocity and hydraulic gradient. |
| Pore Volume | The porous medium’s void-volume that can be saturated with the transmitted fluid. |
| Porosity | The ratio (usually expressed as a percentage) of the volume of voids to the total volume of the soil, rock mass, or other porous medium. |
| Rock-Water Interaction | A reaction between a porous rock and the injected water causing precipitation or swelling or release of fines within the rock. |
💡 Technical Note: The filtration requirement is critical for preventing formation damage. It is determined through on-site testing and is specific to the formation and injection water chemistry.
❓ Frequently Asked Questions
🔍 What is the main purpose of ASTM D4520-18?
This practice provides a procedure for on-site core flood tests to determine the filtration and chemical treatment requirements for subsurface water injection.
💡 What types of water injection projects is this standard applicable to?
It applies to water disposal, secondary recovery, and enhanced oil recovery projects, and is applicable to injection waters with all ranges of total dissolved solids contents.
⚡ What are the key measured properties in this standard?
Key properties include filtration requirement, permeability, pore volume, porosity, and rock-water interactions.
📌 What other standards are referenced in D4520-18?
It references ASTM D653, D1129, D2434, D4404, API RP27, and API RP40 for related methodologies.