The theory of horizontal well test has shown that the linear flow is the dominant flow at intermediate time. However, the existence of a bilinear flow regime as intermediate time flow during the horizontal well transient behavior complicates more the analysis of horizontal well tests. In order to bridge this gap, a mathematical equation describing the bilinear flow has been proposed by Jelmert and Vik for infinite homogeneous and anisotropic reservoirs. By using TDS method, better estimates of the directional permeabilities and the effective horizontal well length are obtained The main objectives of this paper are to reveal the following:

  • The evidence of the occurrence of a bilinear flow in horizontal wells as intermediate time flow regime.

  • The determination of the controlling factors and origins of the bilinear flow.

  • The establishment of an analogy between a horizontal well and a finite conductivity vertical fracture.

  • The application of conventional and Tiab's Direct Synthesis (TDST) methods on the equation developed to determine the reservoir and well characteristics, where hassi-Messaoud field of Algeria.


One of the most significant technological advances in the petroleum industry over the last decade has been the extensive development of horizontal well drilling technique. Horizontal wells are now common in many Reservoir management applications, so it has become important to be able to interpret well test in horizontal wells.

It is well known that horizontal wells, because of their long open interval into which fluid enters the wellbore, exhibit number of flow regimes during the transient period, however depending on the reservoir heterogeneity, well geometry and production conditions one or more of these flow regimes may be missing.

The major purpose of well test pressure analysis is to determine critical formation properties that are of potential in optimizing an individual completion or optimizing the depletion plan of a reservoir.


Early investigation by Daviau et al.(1985). Clonts and Ramey (1986). And Goode and Thambinayagam (1987) revealed the unique reservoir pressure behavior as a direct result of various flow regimes encountered during a Horizontal well pressure test. The different flow regimes that may appear in transient pressure test are early time radial flow in the vertical plane, hemiradial flow, linear flow, late radial flow, and late time linear flow.

Several authors have included The effect of wellbore storage either by analogy to vertically fractured wells (Daviau et al,1985) or by deconvolution of early time rate data(Kuchuk et al.1989). The presence of such effect complicates the analysis of the vital early time flow regimes.

Ozkan et al., 1989; Kuchuk et al., 1990. Issaka and Ambastha., 1992 enhanced the pressure transient analysis by using the derivative functions for horizontal wells. Which finally provided an accurate estimate of the duration of various flow regimes.

Different interpretation methods are used based on the developed models such as specialized plots as semi-log or square root of time. (Goode and Thambinayagam,1987; Odeh and Babu, 1990; Kuchuk et al, 1990) and log-log type curve matching techniques (Clonts and Ramey, 1986, Ozkan et al 1989).The above methods are instructive and time consuming.

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