Deep formation damage caused by killing fluid frequently occurs in blowout wells and clean-up operations may result in early water breakthrough and less hydrocarbon recovery. This paper presents three innovative practices applied in oil and gas wells that suffered blowout accidents for more hydrocarbon recovery. i.e.:
For a blowout oil well, N2 huff and puff process can be applied for clean-up around the wellbore. During the first several cycles, the well got clean-up and output and wellhead pressure increased.
For a blowout gas well in a massive gas pool, controllable drawdown pressure is recommended due to its updip location. The drawdown pressure should be met for both clean-up and minimum water coning. When water breakthrough appears, then neighboring wells at lower locations produce at larger drawdown pressure than that of blown-out well to minimize the impact of water influx on production of blowout well.
For a blowout gas well in a faulted, naturally fractured reservoir, drawdown pressure should be maintained at the level of no liquid-loading in the wellbore. Gas and water co-production should be kept stable. Any shut-in of the well must be avoided.
These methods have been successfully utilized in more than 40 wells for over 50 years. The three typical field examples are illustrated. One of them is an oil well in sandstone reservoir, with double oil rate as the nearby wells. The rest are a gas well in massive carbonate pool with bottom water, with the most prolific gas production in the field, and a gas well in a naturally fractured reservoir, with Gp of over 180 BCF.
Each year tens of thousands of oil and gas wells are successfully drilled worldwide. The overall safety record of the drilling and workover operations is quite satisfactory. On occasion, however, blowout problems can arise during drilling and workover where the control of a well is lost, whenever a well begins to flow uncontrollably.
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