Method of determining the per strata reserve quality of an oil well

A method of evaluating the hydraulic potential of the section of a porous stratum that is filled with an incoming or outgoing moving effluent and that is defined by two depths respectively zlow and zhigh, the method being characterized in that it consists:

• in generating periodic modulation of the flow rate of the well;
• in lowering down the well and in activating for a few periods at the fixed depth zlow a sonde provided:
• i) with a device for precisely determining depth, either relative to the geological series by a gamma ray detector or relative to elements of the well (CCL);
• ii) with a clock;
• and
• iii) with physical sensors suitable for measuring at least the flow of effluent in the well, the pressure, the temperature, the mean density, and the head loss gradient;
• in extracting from these measurements:
• i) the amplitude ΔQlow of the sinusoidal component of the flow rate modulation relative to one of the imposed periods T;
• ii) the amplitude ΔPlow of the sinusoidal component of the pressure modulation relative to the same period;
• and
• iii) the phase delay of the pressure sinewave relative to the flow rate sinewave φlow;
• in determining the complex response Rlow to the cyclical test of period T of all of the active zones delivering effluent into the well between the bottom of the well and the depth zlow, by using the formula;
• R
• low
• =
• Δ
• ⁢
• ⁢
• P
• low
• Δ
• ⁢
• ⁢
• Q
• low
• ⁢
• ⅇ
• -
• ⅈφ
• low
• in raising the sonde to depth zhigh, activating it for a few periods at said depth, performing new measurements, and from the new measurements, extracting:
• i) the amplitude ΔQhigh of the sinusoidal component of the flow rate modulation relating to the imposed period T;
• ii) the amplitude ΔPhigh of the sinusoidal component of the pressure modulation relating to the same period T;
• and
• iii) the phase delay of the pressure sinewave relative to the flow rate sinewave φhigh;
• in determining the complex response Rhigh of all of the active zones delivering effluent into the well between the bottom of the well and the depth zhigh, by using the formula:
• R
• high
• =
• Δ
• ⁢
• ⁢
• P
• high
• Δ
• ⁢
• ⁢
• Q
• high
• ⁢
• ⅇ
• -
• o
• ⁢
• ⁢
• φ
• high
• in calculating the complex response Rstratum of the stratum defined by the fact that the effluent it contains is delivered into the well between the depths zlow and zhigh, by means of the formula:
• R
• stratum
• =
• R
• high
• ·
• R
• low
• R
• low
• -
• R
• high
• in postulating a physical model for the stratum by numerically inverting the mathematical formula giving the theoretical complex response;
• in determining the hydraulic characteristics of the stratum defined by the measured response Rstratum;
• in calculating the well productivity index IPstratum relating to the stratum in question and in deducing therefrom the mean deposit pressure PD in the stratum, by applying the formula:
• P
• D
• =
• P
• DH
• +
• Q
• stratum
• IP
• given that using the sonde, and prior to activating the flow rate modulator, both the stabilized downhole pressure PDH and the net flow rate Qstratum coming from the stratum are measured.