Characteristics and Controlling Factors of Paleozoic Buried-Hill Reservoirs in the Talara Basin, Peru

The Paleozoic (Carboniferous) Amotape Formation in a metamorphic-rock buried hill in the Talara Basin, Peru is an important regional exploration target, where a series of oil and gas reservoirs have been discovered. The daily oil production of Well EA2311 located in the La Guna buried hill in Block X, Peru is 2,890 barrels per day, and the cumulative oil production of Well EA2294 is 1.1 million barrels, indicating that this region has broad exploration prospects. Paleozoic metamorphic-rock buried hills have complex reservoir conditions, and the types and controlling factors of reservoirs in the buried hill remain unknown. These factors restrict oil and gas exploration in this region. Based on paleogeomorphology analysis and by making full use of data such as core data, thin-section analysis data, scanning electron microscopy (SEM) data, well log data, and seismic data, this paper analyzes the conditions for the formation of Paleozoic (Carboniferous) metamorphic-rock buried-hill reservoirs in the Talara Basin, Peru, determines the types of reservoirs, and reveals the main factors controlling the development of fractures in such reservoirs. The results of this study show that the main types of rocks in the Carboniferous Amotape Formation are quartzite and slate, and gneiss and phyllite have developed locally in this formation; the reservoirs are fractured and porous, which can be classified into weathering crusts and inner reservoirs in the vertical direction; the level of development of fractures is related to the thickness and purity of quartzite and the transformation by paleo-tectonic stresses. This understanding provides valuable guidance for the selection of favorable exploration zones in buried hills and the search for the subsequent exploration direction.