The Study Of Mechanism And Enhanced Oil Recovery Of Artificial Strong Edge Water Flooding

Oilfield water flooding development generally contains four stages,including initial water cut stage,middle water cut stage,high water cut stage and extra-high water cut stage.At present,the majority of the oilfields in our country have entered into high and extra-high water cut stage.The main reservoir types of the Jianghe districts in Shuanghe Oilfield is up dip pinchout of lithologies which has edge water that is been controlled by monoclinal structure.The reservoir has experienced high yield,production decline,low and stable stage,and at the moment it has entered the high water cut development period.There is nearly 4000m³/d of water to deal with the way of re-injection in the outside edge.There are some reasons that the main layer,which experienced heavy flooding,and non-main layer share the same well pattern.And oil wells are mainly located in the middle reservoir and up dip pinchout district.In addition,edge position had no injection and no production.So a large number of the remaining oil has not been used effectively in edge position.The recovery ratio of fault-block oil reservoir which has strong edge water is high.In order to enhance the recovery ratio,the successful experience of development of fault-block oil reservoir which has strong edge water has been learned to do wide spacing and high delivery capacity flooding,and artificial strong edge water flooding has been formed.Currently,the methods of enhancing the recovery ratio by artificial strong edge water flooding has begun to be used in some domestic oil fields,and it is still in the further exploratory stage.Based on the overlying analysis,sublayers suitable for artificial strong edge water flooding were selected through the study of the mechanism of enhancing the recovery ratio with artificial strong edge water flooding and the general principles of selecting layers.Through the method of establishing geology pattern and numerical analogue,we get distribution characteristics of remaining oil,reasonable water intake per unit thickness,reasonable pattern well spacing and reasonable re-production time in selected layers,which guide the adjustment of field plan in order to achieve the best effects of water injection and improve oil recovery.The results are as follows:?1?It's the mechanism of artificial strong edge water flooding,which intend to improve displacement efficiency and conformance factor by enhancing water flooding PV,making edge water advancing from"tonguing"into"entire advancing",resuming the producing energy from"pointing recovery"into"entire recovery"and re-accumulating remaining oil,and ultimately achieve the purpose of enhancing the recovery ratio.?2?The general principles of selecting layers with artificial strong edge water flooding mainly consider reservoir factors,development factors and engineering factors.There are factors of selected reservoir that structure is relatively simple,reservoir develop stable with a certain thickness,width of fault,and permeability,and block is relatively closed.That there is a certain original controlled well pattern and producing wells are less or nearly abandoned is selected as developmental aspects.In terms of engineering,it's inclined to choose what the workload of technology and auxiliary project is relative simple and operation is easy.?3?The reservoir data of geology,physical property,edge water energy,injection or production well is analyzed in 16 small layers,?and?formation of Jianghe district,according to the general principles of artificial strong edge water flooding.And 3 sublayers,which are suitable for that,were finally selected.?4?There are some distribution characteristics of remaining oil by establishing geology pattern and numerical analogue in selected layers.Firstly,remaining oil is located in which physical property is relatively good and thickness is large.Secondly,there is still remaining oil,which can be used as one of potential tapping direction,but side oil has been external eruption because of intracontour waterflooding.Thirdly,the remainder oil saturation relatively high in incomplete edge or corner area of flooding network,where physical property and thickness is both not good.However,remaining reserves is limited for that reason,but that area can be used as one of potential tapping direction in extra-high water cut stage.?5?Three selected small layers obtained parameter optimization through numerical analogue in order to enhance the recovery ratio.Finally,it's 20m³/?d·m?as reasonable water intake per unit thickness of V₁₁ layer,40m³/?d·m?as reasonable that unit thickness of V¹₁₂individual layer,which is belong to injection well of edge water and 16m³/?d·m?as reasonable that unit thickness of VI²₁₇ layer.In addition,the reasonable re-production time of study area is 6 months and it can be directly well startup to produce in VI²₁₇ layer,because the layer has been discontinued for more than 6 months.