WELL SURVEYING METHOD Russian patent published in 2010 - IPC E21B47/00 

FIELD: oil and gas industry.

SUBSTANCE: when recording the pressure build-up curve (PBC) for the first 10 minutes, measurements shall be made every 30 seconds, during the first hour - every one minute, during the first five hours - every 10 minutes, during the first day - every 1 hour, during the second day - every 5 hours, during the third day - every 10 hours, and then every 24 hours. Pressure shall be measured with accuracy of 0.01 MPa. Not less than two PBC are recorded at time interval of the well operation, which is enough for the change of bottom-hole zone (BHZ) properties to appear. PBC are rebuilt into pressure differential curves in logarithmic coordinates - pressure logarithm as time logarithm function. Alignment point of curves is found. Coordinates of the obtained point are recalculated and depth of BHZ clogging is determined. Formation BHZ cleaning activities are performed. PBC are recorded again with the above measurements and accuracy. PBC is rebuilt into pressure differential curve in the above logarithmic coordinates. The obtained curve is compared to the last curve prior to BHZ treatment activities. Alignment point of curves is found. Coordinates of the obtained point are recalculated and cleaning depth is determined.

EFFECT: simplifying measurements and calculations, improving accuracy of determination of the fouling boundary of bottom-hole zone and its change after its treatment.

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