用普通源距全波列测井资料识别裂缝和天然气的方法

^RECOONIZING FRACTURE AND NATURAL GAS BY THE DATA OF GENERAL SPACING FULL WAVETRAIN LOGGING

ＡＴＬＡＳ１６０３普通源距全波列测井资料由于源距短，横波及斯通利波信息难以提取，因此其应用受到了很大限制。但据大量资料观察，该全波列测井资料在储层存在裂缝或是含气部位，往往其纵波能量明显衰减，而不单是纵波前波幅度明显衰减。应用能量比法（Ｒ＝Ａ２／Ａ０ ），可以据Ｒ值的变化情况来直观识别裂缝和天然气；另一种方法是能量差比法（ＷＤＲ＝△Ａ／Ａ２）。把ＷＤＲ、Ｒ这两个指标结合起来考虑时，其效果会更好。当记录的纵波幅度值较大（但其首波不限幅）时，可用纵次首波峰值计算能量比、能量差比值；当记录的纵波幅度中等时，宜用纵波第一个周期的能量计算；当记录值较小时，要用纵波前两个周期的能量计算Ｒ、ＷＤＲ。该方法用在川西非常规致密砂岩中识别裂缝及天然气，取得了良好的效果。

Because of ATLAS 1603 general spacing full wavetrain logging data with short saacing, it is difficult to extract the information of shear and Stoneley wave, so that the application of the data is restricted. Through observating a lot of data, the energy and first wave amplitude of Compressional wave are obviously attenuate whileexisting fractures and gas bearing positions. Fractures and natural gas can be visually identified by energy proportionality method (R= A2/Ae ) or energy difference proportinality method (WDR =△A/A2 ) according to the change of R value. When the recorded amplitude value of compressional wave is bigger (but the amplitude of first wave is not restricted), the proportionalities of energy and energy difference can be computed by the peak value of the first compressional wave; When the recorded value of compressional wave is middle. the proportionalities should be computedby the energy of the first period of compressional wave; When the recorded value is lesser, R and WDR are computed by the energies of the first and second periods of compressional wave. A good result of recognizing the fractures and natural gas of non-conventional tight sand in West Sichuan is obtained by the methods.