Predicting the Distribution of Calcareous Glutenite in a Particular Formation

Mahu oilfield is the largest tight glutenite oilfield discovered in China, with a reserve of 1 billion tons, and has a good development prospect. However, the tight glutenite reservoir is characterized by strong heterogeneity, low porosity and low permeability, and is difficult to develop. Calcareous conglomerate was encountered during drilling in many reservoirs of Baikouquan Formation in the fault block of the Xia 72 well in the Ma 13 well block of the Mabei Oilfield, resulting in the deterioration of the physical properties of the reservoir and the decrease of gas logging or oil content, which not only reduced the formation drilling encounter rate, but also affected the later deployment of horizontal wells. The genesis, identification and distribution of the calcareous glutenite of the Baikouquan Formation in Mahu Depression were studied based on core data, thin section identification data, logging data and seismic data. The results show that the study area has a good combination of upper and lower strata which supplied both material and environmental conditions for the formation of calcareous glutenite. The calcareous cements of the calcareous glutenite were formed in the late stage of diagenesis, and their distribution are mainly controlled by sedimentary facies and early faults. The calcareous glutenites have bright-point reflection characteristics in seismic, and their distribution characteristics can be accurately reflected by the maximum amplitude attribute.