A Comprehensive Reservoir Characterization and Water Flooding Optimization for Different Types of Reservoir – Case Study of a Giant Carbonate Reservoir in the Middle East

Abstract

Carbonate reservoirs are of strong heterogeneity. Their geological features and dynamic behaviors vary significantly for different types of carbonates. Characterizing the distribution of different types of carbonates and proposing different development strategies are critical for a successful development of carbonate reservoirs. This paper focuses on a super-giant carbonate reservoir with OOIP (Original Oil in Place) of more than 20 billion barrels. However, it has been naturally depleted over the past 40 years. Its reservoir pressure is approaching the bubble point pressure. Therefore, it is critical and urgent to propose optimized water flooding plan for this reservoir. In this paper, the dataset includes seismic data, well logs, production history, dynamic surveillance data, et al. Firstly, three reservoir types are characterized as good, medium and poor reservoirs based on static and dynamic data. Then, the stacking patterns of different reservoir types are concluded and their distributions are determined, which provide us the foundation to propose customized water flooding plan. Finally, the water flooding performances of different stacking patterns are analyzed and full-field development strategies are proposed based on fine-scale geological modeling and numerical simulation. Results indicate that stacking pattern has intimate relationship with facies map. For example, the distribution of stacking pattern A, in which good reservoir accounts for the majority, is consistent with the distribution of favorable grainstone shore facies, indicating very good reservoir quality that resulted in higher production rate, longer stable production period, and slow decline. In addition, different offtakes, well patterns, pressure maintenance, well types of different reservoir stacking pattern are determined based on the simulation results and distribution of different stacking patterns. The EUR is increased by more than 20% compared with natural depletion. This paper offers a reference case of grouping different types of reservoirs and proposing customized water flooding plan, which help engineers and geologists to better develop other similar fields.

Horizontal well placement optimization based on matrix directional continuous element summation algorithm

“…Deng et al (2010) implemented a comprehensive approach integrating proactive well placement technology, thorough rock physics and petrophysics studies, geomechanical analysis, and real-time interpretation and reservoir simulation, successfully enhancing productivity beyond initial predictions for horizontal wells in the complex offshore field of Bohai Bay. Yu et al (2015) applied numerical reservoir simulation to model CO 2 injection as a huff-n-puff process in Bakken tight oil reservoirs, revealing that CO 2 molecular diffusion significantly enhances oil recovery, especially in formations with lower permeability, longer fracture half-length, and more heterogeneity, providing valuable insights into the effectiveness and key parameters of CO 2 enhanced oil recovery in unconventional tight oil reservoirs. van Vark et al (2004) conducted a simulation study evaluating various enhanced oil recovery processes in low permeability carbonate reservoirs in Abu Dhabi, concluding that miscible acid gas injection emerges as the preferable recovery method due to its favorable interaction with native oil, efficient asphaltene dissolution, and advantageous mobility ratio.…”

“…Reservoir engineers often use the predicted development performance to optimize development plans. Wei et al (2017) utilized a comprehensive dataset, including seismic data, well logs, and production history, to categorize a super-giant carbonate reservoir into three types (good, medium, and poor), established their distribution patterns, and proposed tailored water flooding plans based on fine-scale geological modeling and reservoir numerical simulation, effectively increasing the estimated ultimate recovery (EUR) by more than 20% compared to natural depletion. Li et al (2016) introduced a systematic technique combining analytical and numerical production analysis, pressure transient analysis, material balance analysis, and geological analysis to effectively evaluate reservoir properties and forecast production performance of fractured vuggy carbonate gas condensate reservoirs with complex characteristics.…”