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15 Cards in this Set
- Front
- Back
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How many methods do we have to kill production wells?
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Forward circulation; reverse circulation; bullheading; and lubricate and bleed.
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What are the advantages of forward circulation?
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We produce little to no damage on the formation.
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What are the disadvantages of forward circulation?
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It is less safe because we have a live annulus. We mix oil, gas, and packer fluid which need to be separated later on. We must use high circulation pressures. There is no advantage over reverse circulation so we do not use it.
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What are the advantages of reverse circulation?
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We produce little to no damage on the formation. Hydrocarbons flow through the tubing and x-mas tree. Gas, oil, and packer fluid remain segregated. Surface pressures are low. Low circulation pressures. All wells can be killed this way.
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What are the disadvantages of reverse circulation?
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It is slower than bullheading.
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What are the advantages of bullheading?
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It is fast and cheaper. There are no hydrocarbons brought to surface since they are pumped back into the formation.
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What are the disadvantages of bullheading?
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We can cause damage on the formation. We may cause fracturing. Gas may slip if our pump rate is not high enough.
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What factors limit the amount of pressure available during bullheading?
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Working pressure of surface equipment; the fracture pressure gradient; and burst pressure.
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When do we use lubricate and bleed?
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It is only used if a leaking plug is stuck below the packer. It is an emergency procedure.
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How does lubricate and bleed work?
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We pump some kill fluid, let gas percolate to surface, bleed off partially, and repeat. We never bleed to 0 PSI.
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What information is required before killing a production well?
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Fluid levels (with wireline). Formation pressure. Wellhead working pressure. Fracture pressure gradient. Casing and tubing sizes. Casing and tubing strengths.
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How do we prepare the well for a kill?
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Check the SCSSV to assess if we need to pull it out (if its ID is big enough for the plug). Isolate the well from production control system and ESD.
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What are the requirements for the kill fluid?
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It mus be compatible with the formation; must have the correct weight; and it must be prepared and clean.
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If the kill fluid is lighter than the packer fluid, at what point during the kill will we see the highest annulus pressure?
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When the tubbing is filled completely with heavy packer fluid and the annulus is completely filled with kill fluid.
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What is annular pressure loss (APL)?
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It is loss of applied pressure due to friction on long conduits.
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