Identification of Fracture Types and Characterization of Horizontal Well Development on Fractured-Carbonate Reservoir

Abstract

X Oilfield is located in Persian Gulf Basin, a stable continental shelf region in the northern margin of Arabian Plate. It is an important oil-producing area in the middle part of Mesopotamia Basin. K formation is the major oil-bearing carbonate reservoir in Cretaceous Period. A method has been established to identify the fractured reservoir zone based on static and dynamic data analysis, which determine the reservoir types and fracture distribution in K formation. This research indicates that: 1. The production zones comprise two types of vertical fractures: large-scale fractures and small-scale micro fractures. The large-scale fractures are mainly developed along the faulted zone while the small-scale micro-fractures extend to the whole formation. Therefore, the main reservoir type in K formation is fracture-porosity reservoir which micro fracture is connected by the matrix pore. 2. The vertical small-scale micro fractures control the water flow direction and the development of water flow channel in the process of water injection. The fracture-porosity reservoir type determines the characteristics of oil producer that produce oil without water in a short period and water content with rapid increasing. However, the water rising rate decline year by year. The annual average water cut rate maintain at 2% when the water cut reach to 60%–70%. 3. K formation will preserve in the middle and high-water production stage for a long time. Thus, the key process to stabilize the oil recovery is to supply the formation energy through water injection.

Copyright 2019, IFEDC Organizing Committee.

This paper was prepared for presentation at the 2019 International Field Exploration and Development Conference in Xi’an, China, 16–18 October, 2019.

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