Abstract

Steam stimulation well shows much difference production performance with conventional well. An extensive inflow performance relationship (IPR) for steam stimulation well was obtained by regression based on the thermal numerical simulation. It has been shown that the amount of energy injected and horizontal well length play an important role. Two stages appear about reservoir pressure performance in the production period, joint is at the point where cumulative production to injection ratio is unity; maximum production rate shows two stages, joint is at at the point where ln (Xd) is 0.003. For the same amount of energy injected, production performance is almost identical. Well performance become better as the horizontal well length increase for a specific drainage area. The new IPR equations have been successfully tested through a numerical simulation running and applied in artificial lift designing of two oil fields in China.

Introduction

Although steam stimulation has been successfully used in heavy oil reservoir for decades, there exists unsolved problem in well operation designing, no suitable IPR equation is available for this kind of well. As the progress of horizontal well drilling, horizontal well with steam injection makes this problem more complex.

Several authors have made studies on IPR. In 1968, Vogel developed a famous IPR equation, this equation states the relation between dimensionless bottom-hole pressure and dimensionless production rate for solution gas drive reservoir, reservoir is under the steady state. Reservoir pressure and maximum production rate are constant and can be known with the help of well-test operation. However, this equation can not be used in artificial lift designing for steam stimulation well due to the limitation of well-test operation, reservoir is composite after steam injection and is under strong unsteady state. Obviously, it defies the Vogel's guidelines, reservoir pressure and maximum production rate are definitely changing in the production period. So, the purpose of this work is to extend Vogel's equation, including to construct the relation between reservoir pressure or maximum production rate and recovery; energy injected and horizontal well completion length will be involved. With the same way, water-cut and liquids temperature changing relations can be found also.

Brief of IPR Study Method

The following simplifying assumptions have been made:

  1. Reservoir is horizontal, with no dipping, both of upper and bottom cap rocks have no difference;

  2. There is neither gas cap at the top nor free gas inside the sand and no hydrocarbon distillation occurs, oil viscosity reduction is a principal mechanism;

  3. Fluid saturation are uniform throughout the reservoir, steam stimulation is in the first cycle;

  4. A specific (X type) water/oil and gas/oil relative permeability curve and no temperature dependent was used;

  5. No capillary pressure effect was involved;

P. 887

This content is only available via PDF.
You can access this article if you purchase or spend a download.