Finding the Exploration Sweet Spot — Lessons Learned So Far in the Kurdistan Region of Iraq

Abstract

Abstract

Frontier exploration has a learning curve that requires operators to “figure things out” and isolate the “best portions” of a basin quickly and cost effectively. While climbing the curve often occurs through trial and error, systematic study and integration of the petroleum system elements throughout the exploration cycle can expedite the ascent. In the Kurdish Zagros several key and unique elements of the petroleum system have risen to the top that significantly impacts our assessment of opportunities.

At first glance the Zagros appear to be a “simple” fold and thrust belt. However, regional transects indicate basement depth varies from north to south and plays a key role in the evolution and prospectivity of the Zagros. In the north, the basement is shallower, and the fold and thrust belt appears to have a single detachment level. In the south, the basement is deeper and the presence of a thicker detached Tertiary section results in differences in trap styles and structural complexity. Additionally, throughout the Kurdish Zagros the Mountain Front Flexure may delineate thin-skinned vs. thick-skinned deformation and explain some key differences in the timing of structures.

One of the most enigmatic elements of this region is the spatial and vertical variability of oil and gas properties over very short distances. We observe variations in fluid density, chemical composition, and gas impurities in hydrocarbon accumulations that allude to a complicated charge and hydrocarbon alteration history. Preliminary geochemical results indicate that the presence of multiple effective source rocks at different thermal maturities is a key component to this.

Although the vast majority of reservoirs in the Kurdish Zagros are naturally fractured reservoirs, matrix porosity and permeability are still key components to the storage and deliverability of hydrocarbons to the well bore. Careful analysis of rock data allows us to properly identify environments of deposition and create models that we can use to predict facies successions and matrix properties away from the well-bore. Relying on the evaluation of matrix properties by logs alone leads to erroneous interpretations of pay due to the highly variable nature of carbonate pore systems created by depositional and diagenetic processes.

These lessons learned from Kurdish Zagros further highlight the importance of undertaking a detailed, yet regional, approach to understanding petroleum system elements.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016