偶极横波远探测方位区分新方法

Novel method for dipole shear wave remote detection azimuth discrimination

偶极横波远探测仪器具有测量频率低、频带宽、信噪比高等显著优势,能够精确刻画井旁构造产状,在西北地区碳酸盐岩地层断溶体、断控体储层以及西南地区致密碎屑岩地层断缝体储层等应用效果显著。但由于偶极声源指向呈中心对称导致180°方位不确定性,难以实现方位探测。为克服这一缺陷,提出偶极横波远探测方位区分新方法,使用非对称发射、接收声系的偶极横波远探测测井仪采集多分量偶极横波数据,开展有限差分开展数值模拟并进行现场试验,形成处理解释软件模块。结果表明,与传统的对称接收方式相比,此方法打破了所接收的横波声场的对称性,实现了方位远探测。该方法定向放大了反射体所在方位的反射横波幅度,利用该特征可实现方位区分。现场试验与数值模拟结果一致,验证了该方法的有效性。新方法可为井旁地质异常体方位探测及侧钻井、加密井部署提供有力支撑。

The dipole shear wave remote detection instrument offers significant advantages such as low measurement frequency,wide frequency band,and a high signal-to-noise ratio.It can accurately characterize the attitude of geological structure near the borehole,making it especially effective in fracture-cavernous reservoirs and fault-controlled reservoirs of carbonate strata in north-west China,as well asin fault-fracture reservoirs of tight sandstone and shale strata in southwest China.However,realizing azimuth detection has been challenging due to the 180°azimuth uncertainty caused by the central symmetry of the dipolar source.To over-come this limitation,a novel method for azimuthal differentiation in dipole shear wave remote detection is proposed.Multi-compo-nent dipole data was acquired using dipole S wave remote detection logging tool with an asymmetric transmitters and receivers.The method involves conducting numerical simulations using finite differences and field tests.Additionally,a processing and interpreta-tion software module is developed.The numerical simulations demonstrate that the method can selectively amplify the reflected shear wave amplitude of the reflecto's azimuth,enabling azimuth discrimination.Field test results align with the numerical simula-tions,confirming the method's validity.This new approach provides robust support for azimuthal detection of geological anomalous bodies besides the well,as well as for the deployment of sidetracking wells and encrypted wells.