The method of determining a production well flow profile, including determination of hydrodynamic characteristics of reservoir pay zone

Abstract

The invention relates to oil and gas production industry and can be used in production well logging operations. The method of determining a production well flow (production) profile in terms of hydrodynamic characteristics of individual reservoir units (their productivities and far-field reservoir pressures) in a multilayer reservoir includes temperature Tf(1) and bottomhole pressure pb(1) measurements along the wellbore after the well has been producing for a long time at a known constant rate in a quasi-stationary regime, after which the rate is changed by a predetermined value for a period sufficient for a new quasi-stationary flow regime to set in, and then temperature Tf(2) and bottomhole pressure pb(2) measurements along the wellbore are repeated. Whenever necessary and practicable, additional temperature and bottomhole pressure measurements along the wellbore are performed in different well-operation regimes, at different total flow rates. Then the reservoir pressure plex and productivity Kl are estimated and flow rates Vl are determined for each l-th unit (l=1, 2, . . . L, where L is the top layer number) in each well-operation (production) regime on the basis of bottomhole pressure and temperature measurement data, with the total production rates of the well in all logging regimes being known, by solving the system algebraic equations, starting from the topmost layer L (l=L, . . . , 2, 1).ClQl(T∧fl−T∨fl)=Kl(plex−pbl)(Tlex−T∨fl+εfl(plex−pbl)),Vl=Kl(plex−pbl),where εfl is effective (non-stationary) Joule-Thomson coefficient;Tlex—the average geothermal temperature across the l-th layer;T∨fl—the flowing temperature at the lower boundary of the l-th layer;T∧fl—the resulting flowing temperature at the top of the l-th layer;Cl—the ratio of the volumetric heat capacity of flow above the top of the l-th layer and that of the flow entering the well from the l-th layer;Tcl—the mean mixing temperature of the fluid flow from the l-th layer;Ql—the total cumulative flow rate of the l-th layer and all the underlying layers.pbl—the measured bottomhole pressure at the depth of the layer l.Application of this invention increases the accuracy and reliability of estimation of the wellbore flow (production) profile through determination of hydrodynamic characteristics of individual reservoir units (their productivities and far-field pressures) in a multilayer reservoir.

1 - 4 . (canceled) 
     
     
         5 . The method of determining a production well flow profile, including determination of hydrodynamic characteristics of reservoir pay zone, wherein:
 with reservoir pressures p l   ex  or productivities K l  of all the reservoir units in the bottomhole being known, temperature T f   (1)  and bottomhole pressure p b   (1)  along the wellbore are measured after the well has been producing for a long time at a known constant rate at least in one quasi-stationary regime, then estimate unknown values of productivity K l  or reservoir pressure p l   ex  and determine the total flow rate V l  of each l-th reservoir unit,   or   with reservoir pressures p l   ex  and productivities K l  of all or part of the multilayer reservoir units in the well being unknown, temperature T f   (1)  and bottomhole pressure p b   (1)  along the wellbore are measured after the well has been producing for a long time at least in two quasi-stationary regimes at known and different total well flow rates, then estimate unknown values productivity K l  and reservoir pressure p l   ex  and determine the total flow rate V l  of each l-th reservoir unit;   the reservoir unit pressures p l   ex  and productivities K l  are deduced and total flow rates V l  are determined for each l-th unit (l=1, 2, . . . L, where L is top layer) in each production regime on the basis of the bottomhole pressure p b  and temperature T f  measurement data, with total rates of the well in all logging regimes being known, by solving the system of algebraic equations (1)-(2), starting from the topmost layer L (l=L, . . . , 2, 1).
     C   l   Q   l ( T   ∧   fl   −T   ∨   fl )= K   l ( p   l   ex   −p   bl )( T   l   ex   −T   ∨   fl +ε fl ( p   l   ex   −p   bl )),  (1)
 
     V   l   =K   l ( p   l   ex   −p   bl ),  (2)
 
   
       where ε fl  is the effective (non-stationary) Joule-Thomson coefficient; 
       T l   ex —the average geothermal temperature across the l-th layer; 
       T ∨   fl —the flowing temperature at the lower boundary of the l-th layer; 
       T ∧   fl —the resulting flowing temperature at the top of the l-th layer; 
       C l —the ratio of the volumetric heat capacity of flow above the top of the l-th layer and that of the flow entering the well from the l-th layer; 
       T cl —the mean mixing temperature of the fluid flow from the l-th layer; 
       Q l —the total cumulative flow rate of the l-th layer and all the underlying layers. 
       p bl —the measured bottomhole pressure at the depth of the layer l; 
       L—the top layer number. 
     
     
         6 . The method according to  claim 5 , wherein to set the new quasi-stationary regime the total well flow rate is changed by the predetermined value and then temperature T f  and pressure p b  measurements along the wellbore are repeated. 
     
     
         7 . The method according to  claim 6 , wherein the set value of the total well production rate variation is 25-50% of the initial rate. 
     
     
         8 . The method according to  claim 6 , wherein the time sufficient to reach the new quasi-stationary regime ranges from 12 hours to 2-3 days. 
     
     
         9 . The method according to  claim 5 , wherein the second regime in horizontal well is the shut-in. 
     
     
         10 . The method according to  claim 5 , wherein a high-precision thermo-hydrodynamic simulator is additionally used to predict the temperature and bottomhole pressure profiles along the wellbore.