基于Iverson模型的低渗透率油层压裂高度测井预测研究

The Logging-prediction of Low-permeability Reservoir Fracturing Height Based on Iverson Model

低孔隙度低渗透率砂岩油层常需进行水力加砂压裂改造。为了防止压开围岩,将压裂缝控制在产层段内,需要预测给定施工压力下储层压裂缝的延伸高度。分析压裂缝延伸机理、确定压裂缝形态和方位及延伸方向;利用测井资料计算地层应力和破裂压力,定性分析压裂缝延伸情况。压裂缝的形态取决于地层应力的大小和方向,裂缝的方位垂直于最小水平主应力方向,缝高延伸终止于最小水平主应力高值处。使用改进后的Iverson应力差模型进行压裂缝高度预测。将该方法应用到长庆油田华庆工区储层的压裂工程中,其结果与压后检测高度的相对误差小于15%,与实际压裂及产能情况相符,效果良好。

Hydraulic fracturing is necessary for low porosity and low permeability sand-shale res- ervoir. This needs us to predict the fracture extending height in some given pressures to avert fracturing the surrounding rocks and control the fractures in the reservoir. Firstly, this thesis an- alyses how to know the height of fractures, how to sure the shape and azimuth of fractures and extend directions. Log data are used to forecast the formation stress and fracturing pressures and qualitatively analyse the fractures extendings. The fracture geometries are dependent on the for- mation stress and its direction. The fracture azimuth is vertical to the direction of the main mini- mum horizontal stress where the fracture extending height ends up. The modified Iverson model is used to forecast the fracturing height and process the post fracture responses. This method is used in fracturing process of Ordose Basin, and the fracturing result is below 15% than that of the post fracture detected height. The predicting result is consistent with that of fracturing and production, so the method can be used to guide the fracturing operations.