1. Monitor the pressure response when the acid contacts the formation and
during injection.
· The pump rate should be held constant throughout the job.
If not, the pressure response record is useless.
· The pressure should never increase when injecting the acid.
If it does, the acid is damaging the formation.
· If a pressure increase is seen when acid first arrives at the formation, it
is probably plugging from solids that were present in the treating string.
(A pipe pickling treatment should have been performed).
· A gradual increase in treating pressure while acid is penetrating the
formation, indicates precipitation of reaction by-products.
· A slight increase in pressure should be seen when any diverter
contacts the formation.
If not, the diverter is probably ineffective.
2. Collect and analyse spent acid returns for:
· pH
· Iron content.
· Presence of emulsions.
· Amount, type and size of solids.
· Presence of reaction.
3. Compare productivity improvement with productivity potential.
Real-time computer analysis of formation skin damage is now possible by using
monitoring equipment to measure pressures and rates during the performance of the
job. This information is then transferred to a computer for calculation of bottom hole
pressure and various other parameters. With the computer program (FracRT) it is
possible to optimise the size of an acid job (or stages) during the actual execution,
as the skin damage is seen fall to a minimum. The program calculates and displays:
a. Damage Ratio Value
b. Paccaloni Style Injection Pressure vs. Injection Rate Plots.
Data collected during the job can be stored with the monitoring equipment (3600 or
3305 monitors) or on the computer and used for post job reporting and analysis.
No comments:
Post a Comment