Reservoir Characteristics And Sedimentology Of Lockhart Formation Kohat, Khyber Pukhtoonkhwa, Pakistan.

Abstract

The present account of core analysis in Sahib Gul-1 OGDCL led to the identification of reservoir characteristics (porosity and permeability) and Sedimentology (petrography, micropaleontology, diagenetic changes, and environment of deposition) of the Lockhart Formation. Lockhart Formation encountered in Sahib Gul-1 is of Paleocene age and consists of limestone. A total of 9 samples were collected from the core of the Lockhart Formation in Sahib Gul-1 OGDCL. Thin sections were prepared for their detailed petrographic studies that led to the classification of Lockhart Limestone and its environment of deposition, as well as its diagenetic study. 30 plugs were taken from the core of Sahib Gul-1 and analyzed for reservoir characteristics i.e. porosity and permeability. All the studied samples of Lockhart Formation are classified as PackstoneGrainstone consisting of microfossils and sparite as cementing material. In some samples, distortion of fossils and stylolitic sutures are present as diagenetic imprints. The environment of deposition is high-energy shallow marine. The plug analysis indicates that the porosity is negligible ranging from 1.03% to 4.32% and permeability is in the range of low-fair (0.01-5.31 mD). The formation does not fall in good reservoir quality in the Sahib Gul-1 well due to diagenesis where the porosity and permeability are occluded due to sparite cement as well as tectonic stresses.