Well log Sequence Stratigraphy and Petrophysical Properties of the Shiranish Formation in the Kirkuk Oil Field (K-260 and K-229)

Abstract

The Shiranish Formation comprises the globigerinal marls and limestones of the Upper Senonian (Upper Campanian-Maestrichtian). The present study has been discussed the pertophysical properties of this marly rocks in Kirkuk oil field (K-260 and K-229). The study area is located in northeastern Iraq (Kirkuk areas). This area lies within the Zagros foreland basin, bordered on the northeast by the Zagros Mountains and on the southeast by the Arabian Shield, and consists of linear and high amplitude folds that trend in a northwest-southeast direction. The Shiranish Formation was deposited during the transgression period after the sea level fall marked by the glauconitic contact (SBI) with the Kometan Formation. According to the general facies observation with the gamma ray and resistivity logs patterns, there are two major units in this Formation. The first unit is represented by six cycles of transgressive system tracts (TST) which bounded the upper unit by maximum flooding surface; the second unit is represented by three cycles of high system tracts which unconformably underlying of Aaliji Formation. According to the porosity type and the conductivity properties in addition to decreasing and increasing of shale effect (Gamma Ray) for the Shiranish Formation within K-260 and K-229 there are five petrophysical zones. These zones may be divided in to two Groups:-A.Low petrophysical properties rocks, this include the zones II and IV. B.Good petrophysical properties rocks, this include the zones I, III and V.The zones of group B are important rock units because there are shows of fractured porosity and gas effects in the zones three and five. Where, the zone three is represents a gas effect when the neutron and density porosity are extrusive. While the zone five are represent the fractured porosity in addition to present of gas effects. The first zone is different from the previous two types by the type of rock is limestone and the fabric/porous type is moldic and intragranular grainstone. At the last of this study the researcher is suggested that the Shiranish Formation may be a good reservoir rocks (fractured reservoir).