The Main Controlling Factors on the Evolution of the Cambrian Carbonate Platform in the Tarim Basin and Its Implications for the Distribution of Ultra-Deep Dolomite Reservoirs

Abstract

Cambrian age strata are the critical development and research stratum series of oil and gas reserves in the Tarim Basin, which contains rich oil and gas resources. The restoration of the Cambrian carbonate platform conversion and the main control factors of development has significant implication for the distribution of ultra-deep dolomite reservoirs. Based on a large number of drilling and outcrop profile data, the micro geomorphic characteristics of carbonate platforms in different periods of the Cambrian period are reconstructed in the western Tarim area, and the basin filling and structure, paleoclimate, sea level change, and seawater redox conditions are combined to analyze the main controlling factors of platform development in different periods and establish the platform evolution model. The characteristics and evolution of the Cambrian Tarim prototype basin are mainly controlled by the break-up of the Rodinia supercontinent, and its tectonic sedimentary pattern has evolved from the north–south differentiation pattern at the end of the Ediacaran to the east-west differentiation pattern of the Cambrian. The sedimentary framework of the Terreneuvian was mainly controlled by the development of paleo-uplift caused by structure and the change of seawater properties caused by the sea level variation. In the Series2 carbonate platform with extensive development, the internal differentiation is controlled by the new paleogeographic pattern of “three uplifts and two depressions”, and reef beach facies belt and platform edge begin to develop due to the lowering of sea level. Under the combined action of rapid accumulation of carbonate rocks, gradual stabilization of global sea level, and the change of ancient climate from warm and humid to hot and dry, the platform environment in the west of the Tarim Basin changed from a restricted platform environment to an evaporation platform environment, and the evaporation lagoon area in Bachu was significantly expanded in the Miaolingian. During the Furongian, the basin ended the evaporation lagoon sedimentary environment mainly due to the rise of sea level and developed a restricted platform environment again.