A Novel Correction of Array Induction Logging Data for Horizontal Wells in Tight Sandstone Reservoirs

Array induction logging (AIL) is widely used for post- drilling measurements in horizontal (HZ) wells due to its multiple radial detection depths, high vertical resolution, and cost-effectiveness. However, the core algorithm of AIL, known as "software focusing" SF, is optimized for vertical wells, resulting in a weak focusing effect in HZ wells. This can lead to unexpected responses separation and resistivity horns with apparent values significantly exceeding the true resistivity. In tight sandstone reservoirs, the effects of dipping angle, mud invasion, and resistivity anisotropy are coupled, leading to extremely complicated tool responses. Unfortunately, existing resistivity correction methods are limited to deviated wells with relative dipping below 80 degrees. Therefore, the development of accurate and efficient processing of AIL data for HZ wells in tight sandstone reservoirs is imperative. The main challenge in processing AIL data for HZ wells lies in simulating the tool responses within a three- dimensional (3D) environment. The slow modeling speed, numerous inversion parameters, and limited measured curves make implementing a 3D inversion impractical for AIL data. To tackle this challenge, a novel hierarchical correction method for AIL data in HZ wells within tight sandstone reservoirs has been introduced in this paper. The essence of this new approach is to separate the influences of anisotropy and invasion in HZ wells, simplifying the complex 3D model into a combination of horizontal layered (1D) and cylindrical layered (1D) models. First, this paper established a coefficient library of true thickness correction based on a horizontal layered model to eliminate the effect of thickness, and the horizontal layered model is then simplified into a homogenous (0D) model. On this basis, a direct focusing algorithm for radial focused responses is introduced for the 0D model, improving the forward modeling speed. Furthermore, the responses after true thickness correction are input into the cylindrical layered model to correct the invasion effect. In addition, the anisotropy coefficient is determined by the measured responses of HZ well and the vertical section of the HZ well. Finally, the result of the invasion correction was input into the 0D model to complete the anisotropy correction. The new method significantly reduces the complexity of the inversion model and allows fast and accurate processing of AIL data for HZ wells in tight sandstone reservoirs. Validation with measured data demonstrates that the new method achieves a processing speed of four points per second, with accuracy errors controlled within 3%, meeting the needs of real-time inversion. Meanwhile, the new method can accurately characterize the invasion and extract the electrical parameters of tight sandstone reservoirs, which lays a solid foundation for fluid identification and reservoir evaluation.