The Study Of Horizontal Well Water Cut Rising Model In The Hadexun Oilfield

The donghe sandstone reservoir of Hadexun oilfied is an oil reservoir with edge and bottom water reservoir. Thanks to the adequate natural energy,the horizontal wells of the oil-water phases region easily prone to bottom water coning in the donghe sandstone reservoir of Hadexun oilfied, which cause the oil-water interface and rise with the shape of cone. However, the water cut of horizontal wells in oil region is also growing rapidly because of intrude water from the edge water in the reservoir,this bring about edge and bottom water breakthrough time is short during the development of the whole reservoir.If water cut is increasing too fast, it will inevitably affect the economic benefit of oilfield production in low oil prices today. According to the characteristics of horizontal well development in the donghe sandstone reservoir, this paper study the model of water cut rise mainly from the following several aspects of the donghe sandstone reservoir: classify the type of water cut rise of horizontal wells in the donghe sandstone reservoir and sum up several models of the horizontal water cut rise. On the basis of the type of the water cut rise of horizontal wells, study the water cut increasing rate, and predict water cut for every type. At last, study the mechanism of water cut rise of horizontal wells and put forward the measures for every model to control water cut grow.By analyzing the production data of 95 wells in donghe sandstone oilfield, the paper divide these wells into two categories: one is the wells with water free production period while the others do not. On this basis, we made a graph which vertical is water cut while abscissa is cumulative oil production, to analyze the change of water cut. It sums 6 models of water cut increase in horizontal wells of Hadexun donghe sandstone oil field: model 1, wells has water free production period and the raise of water cut is slow; model 3, wells has water free production period and water cut is revealed a trend of fluctuations; model 4, wells has not water free production period and the raise of water cut is slow; model 5, wells has not water free production period and the raise of water cut is fast; model 3, wells has not water free production period and water cut is revealed a trend of fluctuations.Though research in 6 models of water cut increase in horizontal wells of donghe sandstone oilfield, the result shows that model 3 and model 5 have better development effectiveness while model 1 and model 6 is good, model 2 and model 6 has an actually modest effective.This paper predicted exploitable reserve of these 6 models by using A,B,C,D type water drive curves. The result shows that model 1 had more exploitable reserve than the other 5 models. So we should consider the wells which has more exploitable reserve while taking water control measures.Build a conceptual model of 4 kinds typical wells, through Numerical simulation to research the influence of the height of water avoidance, sandwich, daily fluid production rate and oil-water viscosity ratio on the rise of water cut Through the study: the main influence factors of the model 1 is the height of water avoidance, sandwich, daily fluid production rate and oil-water viscosity ratio; the key influence factors of the model 2 is the daily fluid production rate and oil-water viscosity ratio; the major influence factors of the model 4 is the height of water avoidance, sandwich and daily fluid production rate; the principal influence factors of the model 5 is the sandwich, daily fluid production rate and oil-water viscosity ratio.According to the 4 models the corresponding water control measures was put forward, the main water control measures of model 1:(1) full use the existing interlayer to calculation the interface production;(2) avoid the acidification of the model well. the key water control measures of model 2:(1)take the measure of reshooting and water shutoff;(2) the location of horizontal wells must first be considered when design new horizontal wells in pure oil field,then considering the water cut ratio of horizontal wells, And the horizontal well should be arranged in the middle part of the reservoir which distance of edge water. the major water control measures of the model 4:(1) prevent the model 4 convert to model 5 in the process of the development, the main method is put into production of new wells, transfer and the reshooting measures of some well;(2) calcareous interlayer also exist in the model 4, can not take measures of acid fracturing, the principal influence factors of the model 5(1) well shutdown when it achieve the economic limit water cut;(2) horizontal well away from the oil-water phases region should empty into the artificial interlayer.