The application of Sonic and Gamma-Ray well logs in keybeds determination and the evaluation of the Asmari reservoirs caprock, Pazanan oil field

Category Petroleum Geology
Group GSI.IR
Location The 25 Symposium of Geosciences
Author A.Zarvani-B.Soleimani-H.Bakhtiari
Holding Date 03 July 2007
 

The application of Sonic and Gamma-Ray well logs in keybeds determination and the evaluation of the Asmari reservoirs caprock, Pazanan oil field

 

Abstract:

The caprock prevents the reservoir, Pazanan oil field, hydrocarbon to more upward form a trap. Mudstone is the main component of the Asmari reservoir caprock in Pazanan oil field. This field located at 150km SE Ahvaz with 60km long to 4-6km width. The caprock was evaluated by the help of Sonic and Gamma-Ray well logs and petrographic data of more than 300 thin sections and as well as SEM analyses of selected samples. These analyses carried out on 10 wells samples. Based on these data, the cap rock can be divided into 6 Keybeds: A,B,C,D,E,F. The caprock thickness decreases to 6m in some cases. The maximum value determined in C-keybed. This thinning may be assigned to tectonic activity. Unsuitable caprock lithology causes a well to collapse during drilling. Texturally, several types such as spherolitic, porphyroblastic, enterolitic and nodular are dominance. Anhydrite crystals were under went diagenetic variations and of these marked by replacement and calcitization. Microscopical studies and lithological variations of caprock offers a sabkha -lagoonal environment to Gachsaran Formation. Lithological variations could be detected an alternative of wet to dry hot weather during caprock deposition

tags: QAZVIN