Research On Well Pattern Infillingof ⅧⅨ Oil Groups Of Shuanghe Oil Field In Biyang Depression

Well pattern Infilling technology is one of the methods to enhance oil recovery and also one of regular measures to improve development effect in domestic and international oilfield. The reservoir properties of ShuangHeⅧⅨoil group is poor .The current well pattern of ShuangHeⅧⅨoil group is an irregular five well pattern and the well spacing is 250 to 300 meters. However, it's difficult to inject water for the reason of the threshold pressure gradient is too high, and there isn't enough energy for production well because of lacking of injection water from injection well. These two points are the reasons which result in the fast productivity decline rate and the poor development effect. According to the statistics, in ShuangHeⅧⅨoil group, the composite decline rate of production is 10%, the natural decline rate of production is 15%, the water flood control degree is only 86%, and the ultimate water flood recovery of current well pattern is only 37.0%. Therefore it is necessary forⅧⅨoil group to infill the well pattern in order to improve development effect.According to the reservoir geological conditions and problems in development ofⅧⅨoil group, by using reservoir engineering and reservoir simulation technical, this paper analyses the well pattern adaptability of the current well, studies on well pattern infilling, and demonstrates a reasonable injection-production well spacing and the economic and technical limits of infilling a well. These provide a basis for the next deployment of infill wells. The main research results of the paper are as follows:①Five-point well pattern with well line obliquely crossing with oil-water contact is the preferred well pattern for conventional vertical well infilling in non-essential oil layers ofⅧⅨoil group.②Five-point well pattern which horizontal well as oil well & vertical well as water well ,with the horizontal-section parallel the oil-water contact is the preferred well pattern for horizontal well & vertical well infilling inⅧⅨoil group.②According to the threshold pressure gradient, the oil sands area, economic parameters, the worked out well spacing ofⅧⅨoil group is 200 meters.④The minimum effective thickness a vertical infilling well required is no less than 4 meters, while that a horizontal infilling well required is no less than 3 meters. the minimum reserves a horizontal infilling well required is no less than 5.75×104t. Finally, according to the previous studies,this paper works out 3 well pattern infilling schemes, and then determines the best well pattern infilling scheme with the reservoir numerical simulation technique, and predicts the production of ShuangheⅧⅨOil groups with the best well pattern infilling scheme.