Diagenesis and Burial History of the Lower Cretaceous Travis Peak Formation, East Texas: Controls on Permeability in a Tight Gas Sandstone

摘要

Petrographic and geochemical studies were used to determine the diagenetic and burial history of Travis Peak sandstones in East Texas and to relate the diagenesis to permeability variations within the formation. Permeability in much of the formation has been reduced to less than 0.1 md by compaction, cementation, and minor pressure solution. Travis Peak sandstone is quartzarenite and subarkose, having an average composition of Q95F4R1. The first authigenic cements to precipitate were illite, which coated detrital grains with tangentially oriented crystals, and dolomite. Next, extensive quartz cement, averaging 17% of the rock volume in well-sorted sandstone, occluded much of the primary porosity. Quartz is most abundant in the lower Travis Peak, in well-connected sandstone beds that were deposited in braided streams. Dissolution of orthoclase and albitization of plagioclase followed quartz cementation and occurred prior to mid-Cretaceous movement of the Sabine Uplift. Illite, chlorite, and ankerite precipitated after feldspar diagenesis. Oil migrated into Travis Peak reservoirs in the Late Cretaceous from Jurassic source rocks. Later deasphalting of the oil filled much of the remaining porosity in some zones near the top of the formation with reservoir bitumen.