低渗透油田重复压裂裂缝形态规律研究

Study on fracture pattern law for re-fracturing in low permeability reservoir

达引朋 2 赵文 2 卜向前 2 张矿生 2 李志文 2 吴顺林 2

中国石油长庆油田公司油气工艺研究院，陕西 西安 710018 低渗透油气田勘探开发国家工程实验室，陕西 西安 710018

Research Institute of Oil and Gas Technology, Changqing Oilfield Company, PetroChina, Xi′an 710018, China State Engineering Laboratory for Exploration and Development of Low permeability Oil and Gas Fields, Xi′an 710018, China

油井重复压裂是目前老油田提高单井产量的主要措施之一。为了提高重复压裂的针对性和措施效果，有必要对重复压裂裂缝形态进行研究。文中以长庆油田某低渗透油藏为例，选取典型的菱形反九点井网为分析单元，采用数值模拟方法，研究了考虑注采和一次裂缝影响条件下不同位置的储层应力变化规律和油井重复压裂裂缝形态。结果表明，不同注采比条件下，储层应力总的变化规律是随着注采时间的延长，储层应力变化幅度呈增大趋势；同一注采比条件下，应力改变随时间而变化，总的规律是应力的改变先增大后减小；应力改变最大的时间出现在20~30个月，因而是最佳的重复压裂时机；井网不同位置的油井水力裂缝的转向半径不同，中心井和角井的规律接近，而中间井的规律差别较大，总体上中间井的水力裂缝转向半径小于中心井和角井。

The re-fracturing of oil well is one of main offensive measures to increase the single well production of maturing oilfield. In order to improve the pertinence and measure effect of re-fracturing, it is necessary to study the fracture pattern of re-fracturing. Taking a low permeability reservoir in Changqing Oilfield as an example, this paper studies the reservoir stress change law in different positions and the fracture pattern for re-fracturing under the condition of fracture influence by selecting the typical diamond-shaped inverted nine spot well pattern as the unit of analysis and using the numerical simulation method. The results show that under the condition of different injection-production ratio, the total change law of reservoir stress changes as the injection-production time prolongs. The reservoir stress change amplitude shows a trend of increase. Under the condition of the same injection-production ratio, the change of stress varies with time. The general law is that the change of the stress increases first and then decreases. The maximum change time appears in 20-30 months or so, so it is the best time of re-fracturing. The steering radius of hydraulic fracture for oil well is different in different well pattern position. The law of center well and angle well approximates and the law of middle well is greatly different. On the whole, the steering radius of hydraulic fracture for middle well is smaller than that of center well and angle well.

10.6056/dkyqt201206026