新型贴井壁式阵列方位侧向测井数值模拟与响应特性

在现有侧向测井仪器基础上,提出了一种新型贴井壁式阵列方位侧向测井电极系,该仪器能提供径向和周向方位电阻率测量.该电极系采用贴井壁测量方式,提供5种径向探测深度.利用三维有限元方法模拟了阵列方位侧向测井电极系的井眼影响特性、径向探测特性、纵向分层能力、方位分辨能力,并模拟其对井周地层、水平井非对称泥浆侵入和倾斜地层的响应.在导电泥浆中最大探测深度为1.23m,纵向分辨率为0.3m,可以识别出0.1m薄层,方位分辨率为20°.贴井壁测量时,纵向分辨率不受泥浆和围岩电阻率的影响,能够准确测量井周方位电阻率,较不贴井壁测量具有很大优势,同时利用12条方位电阻率曲线能够反映出水平井泥浆非对称侵入特性,倾斜地层倾角和倾斜方向.

Numerical simulation of the new sidewall array azimuthal laterolog and response characteristics

Based on existing lateral logging instruments,a new sidewall array azimuthal laterolog sonde is proposed,which allows measurement of radial and azimuthal resistivity with five radial investigation depths. Using the three-dimensional finite element method,we simulate the effects of borehole, radial investigation characteristics,longitudinal layering ability and azimuthal resolution. Moreover, the responses of the sonde in resistivity measurement around the borehole, in the horizontal well with asymmetric mud invasion and in dipping strata are also simulated. The results show that the biggest investigation depth of this device can reach 1.23 m for conductive mud. This sonde can also recognize 0.1 m thin bed without mud invasion, with 0.3 m longitudinal resolution and 20åzimuthal resolution. The sidewall way can accurately measure the resistivity around the borehole, basically eliminates the effect of the borehole and surrounding rock on the longitudinal resolution and has more advantages than the non-contact device.The twelve azimuthal resistivity curves can also reflect the characteristics of asymmetric mud invasion in the horizontal well and dipping strata.