Stable Foam

Foam Generating Is Designed To Produce Small Bubble Foam For Maximum Stability. Controlling The Percent Of Soap, Liquid Rate And The Air Rate In The Proper Variables To Maintain A Stable Foam. Fresh Or Produced Water Can Be Used To Produce Foam. Stable Foam Has 2 To 8 Times The Lifting Ability Than Water. This Superior Lifting Ability Is Due To Its High Viscosity, Linear Viscosity And Expansion As It Moves Up The Annulus.

Foam Is Used In Oil Well Servicing In Connection With Drilling Rigs, Production Rigs, Snubbing Units Or Flush-bys. Foam Cleanouts Have A Wide Range Of Applications. Foaming Has Replaced Bailing For A Method Of Removing Sand From Producing Wells. Many Completions And Workover Jobs Are Difficult Under Low Pressured Reservoirs Where Conventional Fluid Circulation Results In Severe Loss Fluids To The Producing Zone.

With Stable Foam Most Of These Jobs Can Be Accomplished Such As:

• Milling
• fishing
• drilling Plugs And Cement
• liner Running And Recovery
• gravel Packing
• well Stimulation
• lifting Fluid Off Gas Wells
• cleaning Out Horizontal Wells

Stable Foam Is Superior Coring Fluid In Under Pressured Reservoirs For Several Reasons:

• less Loss Circulation
• less Core Invasion
• bottom Hole Circulation Pressure Can Be Controlled, Cores Have No Mud Coating

Foam Also Has Many Drilling Applications:

• deepening Surface Hole Drilling In Perma-frost
• removal Of Debris
• running And Pulling Liners
• foaming Horizontal Wells With 1 ¾”To 2 3/8” Coil

Methods Of Monitoring Sand, Drilling Mud, Clays And Debris:

• 5 Gallon Pail Sample
• using A Centrifuge

Using Foam To Put An Injection Well (Disposal) Underbalanced Allows The Formation To Flow Back At Rates Of 300 To 1200 Lpm. Depending On Tubing And Casing Sizes. At These Rates Cleaning Sand And Debris Out Of The Formation Only Takes Hours. Once The Job Is Complete The Injection Well Will Be On A Vacuum Or Have Very Little Injection Pressure.

Stable foam has an excellent safety record with no incidence of down hole fires reported.  This record could probably be attributed to:

• Very little foam (air) enters the hydrocarbon bearing zones because of the low pressure gradients and viscosity exhibited by foam.
• Accelerated clean – out and drilling rates minimize the time that foam (air) is in contact with hydrocarbon bearing formations.
• The gaseous phase in a foam is encapsulated in a film of liquid and any reasonable amount of formation gas is absorbed into the bubble.
• With the use of foam, nominal hydrogen sulfide gas can be neutralized by the addition of chemicals, such as, ammonia or scavenger with the foam.  The gas is trapped in the foam and then slowly released and safely dispersed as the foam breaks in the return tank.
• At higher pressures, nitrogen or natural gas can be used for greater safety if crude oil or flammable solvents are present as in the well.

As A Drilling, Completion And Workover Fluid, The Lifting Capacity Of The Foam In Laminar Flow Is Very High. This Allows Large Fragments Of Rock, Sand And Waste To Be Circulated To The Surface With Low Circulation Rate And Hence A Low Back Pressure Or Circulating Density Against The Reservoir Formation.

Foam Is Made As Needed, Foam Quality Is Maintained And Adjusted By Varying The Gas, Liquid Rates And Foam Injection Pressure. Simple Procedures On Each Unit Will Accomplish This. When Properly Controlled, The Foam Is Stable Until It Leaves The Well Then Breaks Down After A Period Of Time Or By Using A Defoamer.

Foaming A Well By Pumping Down The Tubing And Returning Up The Casing Puts The Well In A Under Balanced State. Rates Are Determined By Well Depth, In Hole Equipment And Formation Pressures. All Wells Are Different, Some Have Very Low Formation Pressure So In This Case We Would Have To Increase Soap Content Which Lowers Density Of The Foam. The Objective Is To Get The Lift Pressure Lower Than The Formation Pressure And Maintain Circulation.

Concern
Formation Contamination
This worry is the fluid, water and foaming agent entering the production zone, swelling the formation clays or making an emulsion which blocks the pay zone.

Answer
Firstly, air foaming agents are bio-degradable.  If formation or KCL solutions are used, the formation clays should not be disturbed.  There is no doubt some foam fluid could be lost to the formation in the initial lift.  Once circulation is established and the hydrostatic head removed, formation flow back should remove these immediately.  Formation damage is minimal compared to high volume fluid pumping where up to 50% could be lost to the formation.

Concern
Blow-out
What happens when a well is unloaded with foam, particularly a steam well, and the formation kicks ?

Answer
The working string is always under control with a B.O.P. in addition to a hydraulic pipe pack-off is installed.  This gives the added ability to move the work string while circulating with B.O.P. open.

String check valves are installed in the work string so as circulation can be stopped and a joint added without having to bleed off the well bore.

If a kick occurred which needed control, this foam unit can immediately become a kill unit, simply by cutting off the air and increasing water input.  If necessary, a high displacement kill pump can be tied in through existing manifolds.  A controlled kick is excellent in sand clean up.

• We have foamed slant, horizontal and vertical wells.
• Heavy oil wells to clean up the sand problems.
• Water disposal’s to help injection rates and pressure.
• Steam wells at Pikes Peak. Mike’s has high temperature foam good for up to 205 degrees Celsius.
• Milled casing and foamed liners into position for Mobil Celtic.
• Perf washed with foam.
• Foamed new wells after they have been perforated under balance.
• Drilled out bridge plugs that had perfs open above plug.
• Drilled out cement.
• New method of using mud motors to drill out cement & bridge plugs.
• Poor inflow wells injected air or foam to build up formation pressure then released pressure. This has helped to increase the flow of heavy oil.
• Foam is used to recover loss drilling fluid.
• 5 Catch Tanks now available, Used for catching returns from foaming operations and used as a catch tank when de-watering pipelines after a hydro test.

A Scope Joint Is Installed Under The Dog Nut Which Allows You To Circulate Down To Clean Out The Cellar Without The Need Of A Rig And Bops. Once A Scope Joint Is Installed A Flush-by Is Used For Future Flushes And Foam Jobs.

The Flush-by Removes Drive Head And Wellhead And Installs 3” Foam Spool And The Scope Head. Break Off Polish Rod And Install The Actuator Into Rod String, This Allows You To Latch Onto The Scope Joint And Lift The Tubing String Up To Secure Dognut Into The Scope Head, By Use Of Leg Bolts. This Allows Returns To Flow Through The 3”Foam Spool Instead Of The Casing Valves. Once Tubing Is In Place Install The Packing Nut On Top Of The Scope Head For Polish Rod. This Allows You To Lower The Tubing With The Rod String While You’re Circulating With Foam.

Foam Job Are More Cost Effective Utilizing A Flush-by Instead Of A Rig.