Plunger WellVent Reduction ProjectG.P.(Skip) DesaulniersBP2006 Natural Gas Star WorkshopPlunger Lift• An inexpensive method to lift fluids from gaswells using a vertical pig.• Requires energy buildup in the casing or nearwellbore reservoir to lift the plunger to surface.• Inadequate energy or too much fluid causes wellto over load and die.• Venting to atmosphere (zero pressure)instantaneously increases differential pressureallowing well to flow.DistancePressureInitial Vent Reduction Project• Automation projectdesigned and funded in 2000.– Environmental project – funding justified on basis ofGHG mitigation commitments and gas loss value.– Upgraded existing RTUs & host system.– Developed new well control algorithms based on LoadFactor and Turner rate.• Pilot installations and testing in 2000.• System sweep in 2001.• Achieved roughly 50% reduction in venting from2000 to 2004.Why is venting wells a bad thing?• Vented gas is lost, never to be utilized as anenergy source.• Potential energy needed to lift liquids is depleted.• Potential safety hazard.– Combustible mixture in the air.– High velocity plunger strikes on the wellhead.• Global warming due to GreenHouse Gasemissions.Issues• ~1000 of the 2300 wells are plunger lift wells.• Lose a well – order a swabbing unit to liftthe liquids out of the well.• Tight Gas consideration – inflow issues.Actions Taken• Interviewed control room staff and workedclosely with the field automation team leader.• Developed two pilot studies in order to makechanges with some scientific control.• Established a new procedure based onplunger lift expertise and pilot well analysis.• Incorporated new procedure into 2ndpilot.And the solution was...• Smarter automation (settings and code.)• Minor maintenance changes at wellsite.• New automation tools to help recognizeproblem situations.• Making believers out of the staff andmanagement.Vent Pilot List A – Start 6/15/05Applied Vent Procedure Set points 10/20/05Vent Pilot List B –Applied Vent Procedure Set points 11/10/05SVR LIST 70 Wells – Apply VentProcedure set points 3/16/06Myths• There is always “another unique or differentwell”.• After flow venting is required to clean up thewell.• Increasing frequency of cycles cuts vent time.• Tubing pressure can drop during shut-in.• Reservoir does not have enough energy forplunger lift.Lessons Learned• Plunger velocities mean nothing if the wellvents.• A well can generally be run in “safe mode” andcontinue to produce.• Load Factor is difficult to understand andevaluate.• Need to have the option to adjust the Turnerrate – critical velocity.New Tools / Awareness•Added vent volume to all production plots•Automated e-mail of vent volumes summaries•Weekly review of vent volumes in productionmeeting•Added daily vent volume application to FDA•Flow time greater than sales valve open time display•Increasing tubing – casing pressure differentialreportSouthern San Juan Quarterly Vent VolumesTotal VentingSummary•Great success thus far 4.0+ bcf/yr down to less than0.8 bcf/yr•Incremental reductions are increasing difficult•Technology is only a piece of the solution - mostsignificant recent reductions are due to revisedoperational practices•Requires constant focus – Teams deliver on currentgoals•Operational beliefs have shifted from “We must ventto produce” to “Venting is one of our last options”