METHOD FOR RECOVERING AND MAINTAINING THE PRODUCTIVITY OF A WELL

摘要

The invention relates mainly to the petrol and gas industry and can be used for recovering and maintaining the productivity of a well. The inventive method for recovering and maintaining the productivity of a well involves an acoustical action on a well and a formation. Said action is performed cyclically, in the presence of a pressure gradient, between the beginning of a cycle and in conformity with a pressure drop between the well and the formation during the time when the well production rate or the injection capacity thereof is decreased, and the end of the cycle when the increase of the production rate/injection capacity is stabilised or the flow between the well and the formation is finished. The pressure gradient is produced by a high capacity pump which is arranged as deeply as possible and operates in a variable depression mode, or by the maximum extraction of fluid from the well, thereby producing a maximum depression or by stopping until said liquid is accumulated. The formation is loaded by significant and variable depressions associated with the acoustic action or, in the presence of a flow effect, by a natural pressure gradient between the well and the formation. The acoustic action is performed with the aid of an acoustic radiator which is dropped in the well simultaneously with underground equipment during the well development and the reparation thereof, before putting it in operation. Said acoustic radiator is arranged in the region of a perforated formation or a selected layer in such a way that it is possible to perform an action on a productive (perforated) area of the formation, for example by selecting an appropriate length of the radiator or the number of series connected radiators. The characteristics of the acoustic action (frequency, power, directional characteristic, type of radiation) are selected and modified during the treatment of the well depending on the well reaction to the action, or depending on geological and physical properties of a collector and fluid, for example the frequency of action performed by the acoustic device in order to excite resonance oscillations in the perforated downhole area of the formation, when the formation density of the collector is of 2500 kg/m <2>, the fluid density of 850 kg/m<2>, a porosity of 0.20 to 0.24, viscosity 2.4 mPa c, penetrability of 1-11 mD, formation compressibility of 0.9 10 < 10>, fluid compressibility 4.2 10 < 10> l/Pa, Young's module of 2 10<10>, Poisson ratio of 0.29, a sound speed in the fluid of 1100 m/sec, a channel radius of 0.005 m, a channel length 0.15 m, is selected equal to 2.5-3.0 kHz, 6.3-6.9 kHz, 10.3-11.9 kHz, 14.2-16.9 kHz and 19.4-21.6 kHz.