Reunderstanding and Potential Exploration Effect of Yangta 5 Reservoir

Yangta 5 Cretaceous reservoir was known to be a massive reservoir with bottom water in the early stage. It has good production effect, but it shows the dynamic and static contradiction of water in high parts and no water in low parts of the structure. Based on the sequential processing of high-resolution seismic data, the framework of rich oil and gas zones was constructed. Below the unconformity is the cutting of the Bashijiqik Formation and above it is the overlying of the Paleogene strata. It drives the re-understanding of Cretaceous Bashijiqike formation stratigraphic correlation in Yangta block, which changed from the previous isothick correlation to the differential denudation correlation. Then, by comprehensively using seismic, logging and production dynamic data, the top argillous interlayer of Bashijiqike Formation was finely characterized by gamma pseudoacoustic inversion. Three sets of interlayers divided the thick-bedded sandstone into four independent production units from top to bottom. The Yangta 5 Cretaceous reservoir type was rerecognized from the previous bottom-water block reservoir to the edge-water stratified reservoir. Based on the above knowledge, when water was found in the upper and lower oil intervals of well YT5–3, the oil production of more than 20,000 tons in the middle interval was achieved by means of re-drilling without water, which provides a new idea for the rolling exploration of reservoir potential.