Patent ID: 8701762

Claim:
A method for determining a fluid influx profile and near-wellbore area parameters comprising: measuring a first bottomhole pressure in a wellbore, operating the wellbore at a constant production rate during a time sufficient to provide a minimum influence of a production time on a rate of a subsequent change of a temperature of the fluids flowing from production layers into a wellbore, changing the production rate, measuring a second bottomhole pressure after changing the production rate, measuring for each productive layer a fluid influx temperature as a function of time after changing the production rate, determining for each productive layer a derivative of the measured fluid influx temperature with respect to a logarithm of time, calculating relative production rates of the productive layers as Y i + 1 = [ 1 + ( ∑ k = 1 i ⁢ h k t d , k ) · t d , i + 1 h i + 1 ] - 1 where Y i+1 is a relative production rate of (i+1) layer, i=1, 2 . . . , h k is a thickness of a k layer, t d,k is a time at which the temperature derivative becomes constant for the k layer, h i+1 is a thickness of an (i+1) layer, t d,i+1 is a time at which the temperature derivative becomes constant for the (i+1) layer, determining for each productive layer a fluid influx temperature change corresponding to the time at which the temperature derivative becomes constant, and calculating skin factors of the productive layers as s = ψ · θ - θ d 1 - ψ where ψ = Δ ⁢ ⁢ T d c · ɛ 0 · ( P 1 - P 2 ) θ=ln(r e /r w ), r e is a drain radius, r w is a radius of the wellbore, θ d =ln(r d /r w ) r d is an external radius of the near-wellbore area, c is a non-dimensional coefficient, ε 0 is a Joule-Thomson coefficient, P 1 is the first bottomhole pressure in the wellbore measured before the production rate has been changed, P 2 is the second bottomhole pressure in the wellbore measured after the production rate has been changed, ΔT d is a fluid influx temperature change corresponding to the time at which the temperature derivative of the measured fluid influx temperature becomes constant.