Transient Pressure Behavior of Dual Lateral Wells

Abstract

This paper presents an analysis method of the transient pressure behavior of dual lateral wells. Conventionally lateral wells have been analyzed using horizontal well analysis techniques. As we will show in this paper, that if the phase angle between the two lateral sections differ from p, they can not be treated as horizontal well and such practices any result erroneous reservoir properties. An infinite conductivity solution for dual lateral wells was developed by coupling both; the infinite conductivity horizontal well model and the superposition concepts. From the sensitivity analysis study, it was found that infinite conductivity solution for dual lateral wells is affected by the horizontal anisotropy, phasing of the lateral sections, dimensionless horizontal separation, mechanical skin, wellbore storage. It is less affected by the dimensionless vertical separation and the contrast between the dimensionless lateral lengths. Transient pressure behavior of dual lateral wells appears to be more pronounced in the cases:for a phase angle decreasing,for a horizontal separation decreasing, andfor a horizontal anisotropy increasing. The effect of the phase angle decreases while increasing the dimensionless lateral lengths and horizontal separation. The effect of the horizontal anisotropy on the pressure behavior is more pronounced for high phase angles. The wellbore storage dominated flow period tends to be more affected for small dimensionless lateral lengths, LD. The effect of unequal lateral lengths and vertical separation are pronounced only at early times. The intermediate time pseudoradial flow period displayed by dual lateral wells is more distinguishable from the wellbore responses in the cases of a large phase angle and a high value of the horizontal separation. It is worthwhile to note that the responses of dual lateral wells having a phase angle, ß=p, may be viewed as an equivalent single horizontal well. Also Tiab's Direct Synthesis (TDS) technique methodolgy for dual lateral wells has been developed, which adds to the analysis of such wells. Few examples are solved in a step-by-step manner, which demonstrate the use of the method developed. Introduction The productivity improvement expected from horizontal wells is usually proportional to the length of the well. As the length of the horizontal well increases, drilling and well control become extremely difficult. In addition, transportation of a large volume of fluid along a long horizontal borehole results in considerable wellbore pressure losses affecting the productivity. In term of the well coverage, dual lateral wells are expected to provide an excellent alternative to the long horizontal wells. A thorough treatment of the well itself based on accurate computational methods for analyzing and predicting the well performance is needed for better understanding the dual lateral pressure behavior. Practically, the main characteristic features of the responses is that the dual lateral wells may be viewed and analyzed as an equivalent single horizontal well. However, this approach is a great simplification and is suitable only for certain phase angles and anisotropy ratios. Therefore, this approximation is restricted to a specific reservoir-well configuration and its use may introduce significant error in estimating reservoir parameters. For this purpose, we present a semi analytical dual lateral model based on that of the horizontal wells. According to our knowledge, there does not exist such a model to date. Literature review Over the last decade, a considerable amount of work has been published on various aspects of multilateral wells. Most of these works have been presented on the performance of multilateral wells as means of new technology to improve productivity. But only few of them treat the transient pressure behavior of multilateral wells. Karakas, Yokohama and Arima(1) have presented an interpretation of several transient tests conducted in multilateral wells. Using a numerical solution, they indicated that most multiple drain hole systems can be approximated by an equivalent single layer, single drain hole systems.

Field Applications of a Semianalytical Model of Multilateral Wells in Multilayer Reservoirs

“…Examples include work on spatial transformation for a deviated well in an anisotropic reservoir (Besson 1990), dual-lateral wells (Fahem et al 2003), multiple horizontal wells Retnanto and Economides 1996;Yildiz 2003), and segmentation technique (Gommanard and Horne 1996). There are also studies of transient solution in layered reservoirs (Kuchuk and Wilkinson 1991;Spath et al 1994;Kuchuk 1996), and field applications of multilateral wells in a multilayer formation (Vo and Madden 1995;Youcef et al 2008).…”

The Impact of Nonuniform Formation Damage on Long-Term Well Performance

“…[8][9][10][11][12][13][14] Pressure transient characteristics of horizontal wells influenced by formation damage have been studied by many researchers since the mid 1980s. [15][16][17][18][19][20] Goode and Thambynayagam 15 were among the first to incorporate the effect of uniform skin factor into the transient pressure solutions for horizontal wells. Later, researchers [16][17][18] have developed pressure-transient models that can handle nonuniform skin distribution as well as selective completion along horizontal wells.…”