Cast Study 01. Seal Off Old Perfs
Summary
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InfuSeal™ was pumped into a vertical well with 2 perf sets 122’ apart with a BHST of 145 F.
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Seven (7) bbls of InfuSeal™ were injected into two formations located at approximately 7600’ and 7700’.
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Diverters were used to assist placement across both zones.
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Fluid loss control material was mixed in InfuSeal™ because reservoir pressure was low.
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After letting the InfuSeal™ cure to a solid, the sealant left in the casing was drilled out with a blade bit.
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The wellbore was then pressure tested.
Below is a cartoon of the procedure:
Challenges of this well
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Seal off two zones that have vastly different reservoir properties in one run. One was sand stone and the other was lime stone. These two zones have different lithology and permeability.
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Highly depleted reservoir which means the sealant need to hold high differential pressure. The well had been produced for about 19 years. Reservoir pressure could only hold about 300 ft of water column. Fluid leaked off quickly into the old fractures.
Solutions
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Combined diverter with InfuSeal™ to enhance the distribution of InfuSeal™ into both zones
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Optimize the recipe of InfuSeal™ to gain enough strength during set-up process for low temperature applications.
Results
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InfuSeal™ was successfully pumped and solidified downhole.
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The sealant left in wellbore is drilled out successfully. Pictures below shows the drill bit and cuttings of InfuSeal™.
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After sealing, wellbore was tested to 2100 psi on surface, corresponding to more than 5000 psi differential pressure downhole.
Cast Study 02. Seal Off Annulus Leakages
Summary
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A horizontal well has been produced for over 3 years.
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It was found that the annulus between the intermediate and production casing has shut in pressure of 550 psi. The annulus could be pumped in at 650 psi @ 3 bpm, signaling a significant leakage of the annulus.
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InfuSeal™ was pumped into the annulus.
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After waiting for 3 days, the annulus was pressure tested and it could hold 1000 psi.
Challenges of this well
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Not exactly know where the leakage points are. And since it was the annulus, it was hard to diagnose their exact depth.
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Not exactly know top of cement. Offset well that had similar issue was treated by pumping cement into the annulus. It was found that a lot of cement was needed. Thus it was suspected that the annulus had very little cement
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Low temperature, estimated to be 85 °F.
Solutions
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InfuSeal™ was displaced in a middle depth of the annulus. Its low density allows it to suspend at that height without settling to the bottom of the annulus. After hardening, this section of InfuSeal™ forms a seal in the annulus.
Operations
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InfuSeal™ was mixed in the mixing tank of a cementing truck and pumped down with the cementing pump. No extra equipment is needed.
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No drill out needed.
Results
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InfuSeal™ was successfully pumped and solidified downhole.
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After waiting for 3 days to let InfuSeal™ set, the annulus was opened. Annulus pressure dropped to 0 once it was opened, signaling that the communication of annulus to formation was stopped.
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Anulus was then pressured up to 1000 psi for 45 minutes, no pressure drop was observed.
