Quantitative evaluation of morphological characteristics of thin sand body: taking the deltaic distributary channel sand body as an example in Shengtuo oil field of Dongying sag, east of Bohai Bay Basin

Abstract Because of the small scale of distributary channel sand body and the superposition of sand bodies in vertical and lateral direction, drilling data with 150–200 m well spacing is difficult to describe its scale, shape and connectivity characteristics effectively. It has a great restriction on the recovery of these reservoirs. Taking Sheng2 Block of Shengtuo Oilfield as an example, the architectural elements of distributary channel are quantitatively investigated by using dense-drilling well and seismic data. Based on frequency division seismic data, the boundary of distributary channel belts are described vertically and laterally, and then the scale and morphological characteristics of channel bodies in the channel belt are characterized by using local dense well pattern data. The target layer can be divided into six channel belts longitudinally. After seismic frequency demultiplication, 60–75 Hz seismic data was used to describe the distribution of channel belts. From the bottom to the top, the width and distribution range of the channel belts decrease as a whole. Channel belt thickness and its width show linear positive correlation. On the channel-belt cross section, channel stories on the dense drilling-well logging profiles are identified with reference to the profile geometry of the distributary channel. On the channel-belt cross section, the projection distance between wells is fitted to a linear correlation with the thickness variation of channel stories. The ratio of the two parameters decreases from bottom to top of the target layer as a whole. The channel shape parameters predicted by the dense drilling-well logging section are of great significance to the study of paleocurrent deposition and paleohydrological evolution. At the same time, it has guiding significance for the development and adjustment of oil and gas reservoirs.