AE法油田最大主应力值的测量及其与油产关系

THE MAJOR PRINCIPAL STRESS OF OIL FIELD DETERMINED BY AE AND ITS RELATION TO PRODUCTION

介绍了笔者提出的声发射（AE）估测法。强调考虑孔隙压力的重要性，给出了科尔康油田九口井的测量结果和讨论：该油田现今地应力的有效最大主应力值σ1在762～1325m处随深度变化的规律；依据笔者提出的有效最大主应力值与钻井产油情况成负相关关系的观点，推断所测各井的产油情况；白2井深度为972．8～974．6m处的安山岩AE信号多寡有明显各向异性，由于此深度井段处σ1值明显偏低，推测安山岩岩层可能为裂缝储油岩层；AE法结合孔隙压力可给出σ1值，地层倾角测井资料给出孔壁崩落的优势方向即最小水平主应力方向，钻孔压裂可给出泵压力即最小平主应力值σ3，于是一个中间主应力σ2为上覆岩层压力，可以较精确地获得最大和最小主应力在水平面内的准三维应力状态。

AE stress estimation method is presented with emphasis on the importance ofpore pressure. The results of stress measurement in Ke'erkang oilfield by AE method aresiven and discussed. The regression equation is given for the variation of the effectivemajor principal stress σ1 with the depth of 762～1 325 m beneath the surface. There is thenegative correlation between the production of oil and the value of effective major principalstress and the state of production for each well is predicted. Based on notable anisotropy ofAE signal of andesite between 972. 8～974. 6 m in Bai 2 well and lower σ1, it is inferredthat andesite reservoir belongs to fractured oil reservoir. In the light of effective majorprincipal stress σ1 determined by AE method and in consideration of pore pressure in rock,the magnitude of major principal stress σ1 at oil well can be obtained. From shut-inpressure during oil well hydrofracturing, the horizontal minor principal stress σh isdetermined, and the middle principal stress σz is calculated from the overburden. Thedirection of horizontal minor principal stress can be given by preferred orientation of wellwall breakout. Thus a quasi-three dimensional stress state is obtained.