Surveillance Helps to Get a Better Understanding of Reservoir Connectivity in Azeri Part of ACG

Abstract

Accurate and timely information is essential to monitor, control and manage reservoir and well performance. At the present, production and reservoir engineers as well as production geologists have a challenging task of managing oil and gas reservoirs. This requires a broad knowledge of the reservoir supported by fit-for-purpose integrated technologies and real time access to relevant data. In the Azeri-Chirag-Gunashli (ACG) field development, downhole information is commonly acquired through uses of LWD (logging while drilling) tools to obtain a standard log suite and obtain formation pressure measurement, production logging and well testing. In addition, Downhole Temperature Sensors (DTS) has been installed on someACG wells to provide continuous temperature readings across the reservoir so as to obtain critical understanding of reservoir behaviour, connectivity and fluid distribution.ACG structure is located in the offshore of Azerbaijan part of the South Caspian Basin (Figure 1). The structure is an elongate anticline with 3 main accumulations ( Figure 2): 1). Shallow Water Gunashli (SWG) is in the northwest operated by SOCAR and on production since 1980; Deep Water Gunashli (DWG) extended from SWG to the east and became a part of ACG field operated by AIOC with production start-up in 2008; 2). Chirag situated in the centre of the structure that has been on production since 1997; 3). Azeri is in the south east which is in production since 2005(Wethington et al., 2002. ACG structure is complicated by the presence of several mud volcanoes and series of faults and seismic elements cutting field along the length. Development of field is under 30 years PSA that expires in 2024.This field contains 16 hydrocarbon-bearing reservoirs of Pliocene age. Each of the reservoirs is regionally identifiable, laterally extensive and correlatable within the long distance. They comprise stacked fluvial-deltaic sandstones deposited by the paleo-Volga delta, flowed from the north to the south into the lacustrine South Caspian Basin.The main producing interval in Azeri field is a Fasila reservoir that has been subdivided into 5 sublayers (Fasila A,B,C,D, & E) based on the first appraisal well stratigraphy. A stratigraphic section of Fasila reservoir from one of ACG wells shown on Figure 3 illustrates high net-to-gross (NTG) Fasila B and Fasila D sublayers separated by lower NTG Fasila A, C and Fasila E layers.Azeri development proceeds under crestal gas and peripheral water injection support. Therefore understanding of compartmentalization of the structure plays significant role in production efficiency.

Peculiarities of Azeri-Chirag-Guneshli Field Compartmentalization

“…Ряд промысловых исследований подтвердили сомнения в степени гидродинамической разобщенности площади. В частности, результаты трассерных исследований пласта Перерыв указали на достаточно хорошую связь в межскважинном пространстве [1]. Показательными также стали продолжительные исследования поведения непроводящей зоны в куполе залежи, которая при создании определенного градиента давления становилась проводящей, что было отмечено прямыми измерениями пластового давления [2].…”