Each province and territory in Canada sets out the measurement requirements that each oil and gas operator must follow when producing energy from its jurisdiction. This also includes accounting and reporting of the fluid volume. To put it clearly, it comprises of methods allowed to determine the volume produced either by physical measurement or using mathematical procedures to arrive at the desired result. Thus, equipment such as wellsite separators, wet meter packages, line heaters, gas dehydration units, and oil treaters, are required to adhere to such regulations.
Government Agencies Regulating the Oil & Gas Industry
Here are the regulatory authorities that set out the requirements in western Canada for the measurement of gas and liquids:
- BC Oil & Gas Commission (BC OGC) – Drilling and Production Regulation
- Alberta Energy Regulator (AER) – AER Directive 017: Measurement Requirements for Oil and Gas Operations
- Saskatchewan Energy and Resources Ministry – Directive PNG017: Measurement Requirements for Oil and Gas Operations
- Manitoba Petroleum Branch – Drilling and Production Regulation, Part 10
Each province has developed standards of accuracy for gas and liquid measurement. They depend on a variety of aspects, including royalty, equity, reservoir engineering, declining production rates, and ageing of equipment.
Common Methods of Oil Measurement
Listed below are the four methods used for the measurement of water, oil, and gas production:
- Spot – It refers to random testing of a single oil well with a portable test separator.
- Single Well Oil Battery – It uses a test separator and oil storage tank for a single oil well.
- Oil Satellite – It is a facility used for testing multiple oil wells. Typically, it includes a test separator with no oil storage tank.
- Oil Battery – It is also a facility used for testing multiple oil wells and includes a test or a group separator with oil treating and oil storage tanks.
What Does it mean to put a well on “Test”?
When you put a well on test it means that you are determining the volume of oil, water, and gas that a single well produces over a given time (typically 24 hours). A test separator is used to separate the fluids into their single phases of fluid and gas. Gas is measured using an orifice meter and fluids are measured using a turbine or positive displacement meter. Fluid samples may also be drawn during this time to determine the make-up or quality of the oil and gas.
Design of Oil Production Headers
An oil header consists of multiple valves connected to each well flow line that directs the oil production to either the test separator, pig receiving trap, or group separator. The number of wells connected to a header depends on the volume of the oil produced per month for each well.
Although single well measurement provides the least uncertainty, it is not the most environmentally friendly method and is also the most expensive option to operate. Oil satellite or oil battery measurement is the most cost-effective method. It incorporates a test manifold or a header system to connect multiple wells to a test separator.
AER Directive 017 – Proration Well Testing Frequency Requirements
The table reflects the requirements for proration well testing for conventional crude oil wells.
| Class | Name | Oil Rate (m3/day) | Min. Test Frequency | Min. Time Between Tests (Days) | Min. Test Duration (Hours) |
|---|---|---|---|---|---|
| 1 | High | > 30 | 3 per month | 5 | 12 |
| 2 | Medium | > 6 but ≤ 30 | 2 per month | 10 | 22 |
| 3 | Low | > 2 but ≤ 6 | 1 per month | 15 | 22 |
| 4 | Stripper | ≤ 2 | 1 per quarter | 45 | 22 |
Here are a few things to keep in mind:
- Generally, the classification for each well is determined semi-annually, depending on the average daily oil rate. The operator should change the class of a well accordingly if it experiences operational changes that may modify its oil rate. Also, it helps to decide the average daily oil rate based on the number of producing days, instead of the calendar days.
- To obtain more representative test data, it helps to conduct more prolonged duration tests for wells that exhibit erratic rates.
- If more than the minimum number of tests are carried, it helps to reduce the minimum separation time between tests.
- For Class 1 wells, the minimum test frequency depends on the assumption that the well is on production for the entire calendar month. You can reduce the test frequency to two tests in a month if it is shut-in for at least ten days during the month. It can further be reduced to one per month if the well is shut-in for at least 20 days during the month.
- The assumption for Class 2 wells is that they are in production for the entire calendar month. You can reduce the test frequency to once a month if the well is shut-in for at least 15 days during the period.
Determining the Number of Wells in a Test Header
- The Header is in the Same Building as the Test Separator
In this case, it helps to purge the test separator by allowing at least two liquid dumps to occur before the next well test. - The Header is not in the Same Building as the Test Separator
Make sure enough purge time is allowed so that the new test well liquids can replace the fluids from the previous test. - Two or More Wells are Tied into a Common Flow Line
In this case, only one well should be used for the test, while others must be shut-in. Ensure enough purge time is allowed, so the new test liquids replace the ones from the previous production condition.
Get Meter Packages that Comply with the Regulations
At Aspire Energy Resources Inc., we have built many oil test headers with a variety of configurations over the years. We carry the best range of meter packages to meet the varied needs. For more information about wellsite separators, oil treaters, field header or test separator packages, please call us at 403-314-5422 or toll-free at 1-800-993-9958.
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