Documentation for Barrier Tests
The results of all BOP equipment pressure and function tests shall be documented and include, as a minimum, the low and high end test pressures, the duration of each test, and the results of the respective component tests.
Pressure tests shall be performed with a pressure chart recorder or equivalent data acquisition system and signed by a pump operator, contractors tool pusher, and operating company representative.
Problems observed during testing and any actions taken to remedy the problems should be documented.
Manufacturers should be informed of equipment that fails to perform in the field.
When a well barrier/element test fails, it shall be reported and the failed component repaired.
Different Barrier Types
Fluid Barriers:
- For a column of fluid to be a barrier, it must be controllable and monitorable.
- The fluid can be brine, crude oil, gas, water, completion fluid, or a combination.
Mechanical Barriers:
- Casing below the packer
- Packer
- Tubing
- Tubing hanger/Hanger spool
- Xmas tree
- BOP stack
- Coiled tubing stripper
- Wireline packoff
- Wireline lubricator
- Wireline grease injection flow tubes
- Wireline BOP’s
Completion operations are encountered with risks like any other project.The main risk in completion operations can be addressed as a well control incident.
Therefore, systematic risk management is necessary in order to minimize the
unwanted outcomes. Risk management is a systematic effort to identify, evaluate, prioritize, target and minimize or if possible, eliminate the risks of an operation and prevent the unfortunate events from happening.
Management of Change or MOC is a method of management that ensures safety, health and environmental risks are under control when a company makes changes in documentation, personnel, operations and facilities.
The main benefit of Management of Change is that as a process, it helps the manager to avoide the consequences of undesirable safety and health hazards through planning and coordinating the implementation of change in the company.
An inflow test is performed by reducing the hydrostatic head above the item to be tested by circulating to a lighter fluid. These tests are generally carried out to verify if there is communication with the formation through the casing, liner lap or past a cement plug.
Most of the applications are in connection with testing of squeezed off perforations and casing leaks, testing liner-laps, float shoes and float collars, cement plugs and bridge plugs.
Inflow Test (Negative Pressure Test) Failure:
During a negative pressure test, if any pressure is seen at the surface, the test fails. If the pressure is observed on the annulus side, it means that the liner top and the bypass may be leaking. If the pressure is seen on the drillpipe and it’s equal to differential pressure, then it means that the bypass is leaking. If the pressure is greater than the differential, then the liner top may be leaking.
The additional steps which can be taken if the negative pressure test fails in order to prevent additional formation fluids to enter the wellbore are:
- Open the bypass
- Circulate bottoms up through the choke to get rid of any formation fluids in the annulus
- Circulate the drillpipe with mud to bring the light fluid all the way up to surface
- Close the bypass
- Pump cement through the packer at the liner top
- Squeeze the cement
- Rerun the test
Procedure for Circulating to Lighter Fluids (Diesel etc.)
RUN retrievable packer with circulating valve, safety joint and short tail on drillpipe, to depth to be advised by Operations Engineer.
SET retrievable packer at advised depth and test annulus with 1000 psi in order to check that packer is properly sealing and that the tool assembly is functioning properly before RIH any further.
Generally, the retrievable packer should be set at some 50 ft above the interval to be tested (or 50 ft above TOL) in order to minimize any possible influx.
OBTAIN prior approval from the Head of Onshore/Offshore Operations for inflow testing during the hours of darkness.
CIRCULATE the drillpipe to a lighter fluid until the required drawdown is accomplished. (An air cushion may be used) After having circulated the well to achieve the required drawdown, PERFORM the inflow test on the well for 15 minutes as detailed in the Drilling Program.
Procedure for Circulating to Lighter Fluids (Diesel etc.)
UNSEAT retrievable packer. CIRCULATE and OBSERVE well dead. POOH and L/D retrievable packer.
It is critical to ensure that the column of fluid in the isolated zone that will be inflow tested is clean and uniform in density. If different densities are present, it can lead to a u-tube situation that will give false readings for the inflow test. This can lead to very serious consequences and unnecessary expenses.
