碳酸盐岩缝洞型储层是我国西部探区重要的储层,包含较多的孔、洞、缝,其波场信息复杂,常规偏移成像对其成像效果不佳,这已成为制约勘探发展的重要因素.为此本文推导并实现了基于反演思想的高精度最小二乘逆时偏移成像方法,并将其推广应用到碳酸盐岩缝洞型储层.通过对三个基于西部探区实际地质情况建立的典型模型的成像试算,可以发现:与常规逆时偏移结果进行对比,最小二乘逆时偏移能够准确的刻画出裂缝溶洞的位置、形状、大小,验证了该方法在碳酸盐岩缝洞型复杂地质模型的保幅性和成像精度方面的优势.
Fracture-type carbonate reservoirs are important reservoirs in western exploration area, containing many holes and joints with complex wave field information. Conventional reverse time migration (RTM) will produce poor imaging result which restricts the development of exploration. This paper presents the theory and work flow of least square reverse time migration (LSRTM) and applies it to the fracture-cave carbonate reservoirs. Numerical test on typical model which is based on the actual geological conditions in western exploration area and comparison with RTM show that LSRTM can accurately depict the position, shape, size of cave cracks and has the advantages of precision, amplitude preservation.