Operator Workflow

North American Crude Grading Basics: API, Sulfur and What Buyers Actually Look At

Crude oil is not one product. It is a range of densities, sulfur levels and sediment contents that affect how it is handled, how it is priced and how it is processed downstream. API gravity tells operators how light or heavy the oil is. Sulfur content affects corrosion risk and refining cost. Sediment and water set minimum handling requirements before the oil enters a pipeline or a tank.

Gravity and sulfur

A higher API gravity means lighter oil that typically commands a higher price. Sulfur makes oil sour and more corrosive. Operators who collect lease samples and send them to an assay lab keep the buyer and the downstream user informed before the custody transfer happens. The sample chain of custody becomes part of the measurement record.

Custody transfer

Sales meters, proving runs and sample points all feed into custody transfer. The operator should keep the meter calibration records, the meter factor history and the sample report together. When a dispute arises over volume or quality, those records become the starting point for resolution.

Documentation and the field ticket

OpsFlo can store sample analysis tickets and custody transfer records in one place. When the lease operator, purchaser or midstream partner needs the assay data, meter factor and transfer volume, the operator can share it from the same record instead of emailing PDFs from three different systems.

Keeping those records in one system makes https://opsflo.app/ workflows easier to search after an audit, with sample analysis tickets and custody transfer records attached.

Sources and further reading

• API MPMS Ch 20.1: Allocation measurement
• API MPMS Ch 8.1: Manual sampling
• EIA: Petroleum data
• eCFR 30 CFR 250.1601: Oil and gas measurement