On RAI and FDFE Simulations of Acoustic Well Logging Scheme

Numerical simulation can help us to understand the characteristics of the complicated wireline and LWD (Logging While Drilling) acoustic wave fields. The RAI and FEM are commonly used to simulate the acoustic logging wave fields. The former is numerically fast but is difficult to implement for non-axial symmetric models such as tool isolation design and acoustic LWD tool eccentricity. On the other hand, the FEM can be numerically demanding for large 3D models but can handle general spatial variations of elastic properties. This paper extends the application of RAI method to calibrate and associate with Frequency Domain Finite Element (FDFE) method in conjunction with the Perfectly Matched Layer (PML) to simulate the acoustic well logging response in complicated borehole environment. In the RAI method, we have improved the implementation scheme to essentially control the accuracy and to match the geometry of FDFE simulations. The examples to combine the two methods to ensure the correctness of the numerical simulations in complicated wireline and LWD acoustic reflection image are presented.