At present,thermal recovery by steam injection is a main method for heavy oil recovery.In the process of steam injection,the parameters such as pressure,temperature,dryness and thermal loss interact,according to the supplied mathematical model of wellbore heat transmission,the steam parameters can be simulated accurately.The steam parameters vary with pressure and temperature,and thereinto,the pressure drops of steam—fluid phases vertical flow are calculated by this model with classical Beggs-Brill method;ascertained the influence of collar on the coefficient of global heat transfer,furthermore,corrected overall heat transfer coefficient.All these factors are taken into consideration.By sample calculation and comparison,it indicates that the model is reliable.

Drilled horizontal well is not absolutely horizontal, the well trajectory is undulant as wave shape. When the bending degree of wellbore is big,the conventional calculation formulas for horizontal well produetion would cause great error. It is necessary to further analyze the deliverability characteristics of horizontal well. In this paper,the horizontal well with curved trajectory is approximately regarded as a continuous structure which composed of a series of slant wells. We add two modifying faetors of slanted pseudoskin coefficient and partial penetrated pseudo-skin factor,and set up the slant well production formula for anisotropic reservoir. The production caleulated by the slant well production formula is compared with the Joshi＇s horizontal well production formula. We also discuss the effect of curved trajectory on horizontal well production. The results show that the curved trajectory can overcome the low vertical permeability and ensnre the high production for horizontal well when the anisotropy is strong. The horizontal well production increases with increase of slant angle of curved section. When the reservoir anisotropy is weak,the curved trajectory will reduce the horizontal well production.

For the sake of calculating horizontal well productivity in anisotropic reservoirs accurately,five kinds of anisotropic correction methods for horizontal well productivity formula are analyzed and some problems of existing correction methods discussed.By expressing permeability as the forms of arithmetic mean,geometric mean and harmonic mean,the productivity of horizontal wells decreases in turn,i.e.,geometric mean and harmonic mean correction can show the influence of permeability heterogeneity on the productivity of horizontal wells better than arithmetic mean correction.Based on the correction method of Chen′s formula,a new Joshi′s anisotropic correction formula is derived,and the result is in accordance with the one from Chen′s.Case study indicates that the anisotropy has a great influence on productivity of horizontal wells.

稠油由于沥青胶质含量高,蜡质含量少,因而粘度很高,流动困难,开采难度很大。热采技术作为稠油开发的主要手段,已经广泛应用于国内外稠油油藏的开发。介绍了目前稠油热采的主要方法,并根据稠油开发中存在的问题提出了今后稠油热采技术的发展趋势。