New Method for Characterizing Internal Structure of Fault-Karst Reservoirs and Analysis on Acidizing Fracturing Effect: A Case Study in HLHT Oilfield, Tarim Basin, NW China

Abstract Superimposed tectonic movement and karst erosion resulted in a combination of fractures irregular caves deep/ultradeep carbonate rocks, typically along major fault swarms. Outlining these fault-karst reservoirs mainly depends on recognizing the strong reflection seismic profiles; however, characterizing their internal structures is still difficult, which are represented as weak amplitude profiles. This study intended to propose method dissect structure reservoirs, contains four steps: (1) elimination signal interference by covering bed with energy recognition low based data conversion, frequency division, inversion; (2) gradient tensor analysis an anisotropic Gaussian filter for reservoir outlining; (3) faults cave basis wave-based (4) reevaluation number scale well test results verification volumes hydrocarbon reserves. The was used evaluation Halahatang (HLHT) oilfield, located north Tarim Basin. show that effectively recognized, error predicted depth decreases from more than 20 m before less 4 now; drilling success ratio increases 70% 90%. In addition, supports untapped around shut-in wells, provides guidance sidetracking plans. Further, comparing geophysical volume reserve production performance, certain can be evaluated; this basis, producing wells received high yields targeted acid fracturing. summary, improves prediction accuracy recovery efficiency reservoirs.