PRODUCTIVE STRATA OPENING METHOD AT DRAWDOWN Russian patent published in 2015 - IPC E21B21/14 

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to the area of oil and gas industry, and namely to methods of producing horizons opening by wells. The method includes running in of drill pipes with a drilling bit and containers with pressure gages to the well. Upon the hole cleaning surveys are made in order to set drilling modes at drawdown, thereafter upon beginning of flushing liquid circulation with a gaseous agent at least three drawdown-generating modes are made for delivery of the aerated flushing fluid. At all modes values of pressure are measured, time is recorded and pressure losses are identified within the interval from the pressure gage installation site up to the wellhead. The curve is plotted with the obtained data and the required mode for delivery of the flushing fluid and gaseous agent is identified against this curve. The mode maintaining bottomhole pressure and the preset drawdown value is selected so that the permanent drawdown value is ensured at the stratum opening within its whole thickness regulating bottomhole pressure by circulation chocking at the blowing line, which values is calculated for all types of drilling operations considering the stage of deposit development. For conditions in the newly drilled deposits pressure variations are compensated by the blowing line choking, and its value is defined bore arch type of drilling operations by calculation. For conditions of the long-term operated deposits the value of chocking pressure is defined on-the-spot by direct measurements of buttonhole and formation pressure in real time mode.

EFFECT: improved quality of the productive strata opening, reduced time of opening, exclusion of emergencies during hole boring.

1 dwg