Can mud filtercake impair production?
The remaining filtercake in a wellbore can have a severe impact on the flow capacity of a sand control screen or gravel pack and screen. Constien & Associates offers drill-in fluid and wellbore clean-up treatment selection and evaluation. With this testing, we are able to help identify the least damaging drill-in fluid for the formation and sand control screen and / or gravel pack and optimize cleanup systems based on drill-in fluid, screen and down-hole conditions. The method is described in SPE 112497.
Typically screen selection or screen and gravel pack testing is completed first. Once the screen has been selected, then drill-in fluid and clean-up testing can be performed using the actual formation and screen that was selected for use in the well.
C&A has developed testing protocol and equipment that allows dynamic flow and fluid loss across unconsolidated formation material at shear rates, temperatures, differential pressures, and times representative of mud circulation rates in the wellbore. By using this test method, we are able to dynamically deposit filtercakes on consolidated or unconsolidated formation material under simulated wellbore conditions.
The dynamically prepared filtercakes grow to an equilibrium thickness depending on the shear rate, differential pressure, and temperature making them more representative in composition and mass to wellbore filtercakes so that their damage to formation, gravel packs and / or screens can be better evaluated. The effectiveness of cleanup systems can also be determined by circulating the fluids across the mud filtercakes at typical shear rates, differential pressures and temperatures before allowing static soak conditions.
At the end of the test, the screen and formation material or screen, gravel pack and formation material are stressed together simulating a wellbore collapse, or left with an open annulus, depending on the well conditions. The permeability of the formation and screen, or formation and screen and gravel pack, are then measured and compared to the initial values to determine flow capacity impairment.
The ability to create a drill-in fluid filtercake on multiple test cells simultaneously allows for a great deal of flexibility in the design and set-up of the tests. Additionally, the tests can be performed on consolidated or unconsolidated core material.