Rate Transient Analysis Transforms Exploitation of Mature and Tight Fields

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_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23731, “Unleashing the Potential of Rate Transient Analysis: Transforming the Exploitation of Mature and Tight Fields, 40-Year Mature Field Case Study,” by Amr Gharieb Ali, Apache; Mohamed A. Gabry, SPE, University of Houston; and Ahmed Algarhy, SPE, Marietta College, et al. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ The objective of this paper is to address the power of old, cheap data integration with the rate transient analysis (RTA) technique in the development of mature and tight fields. The absence of sophisticated reservoir modeling data further complicates the situation. However, the paper intends to explore the potential of diverse sets of production data over an extended period, available for interpretation and integration with production operations data, to revolutionize the exploitation of mature and tight fields. Introduction Mature oil fields, such as the subject Field X, which commenced production approximately 40 years ago from late Cretaceous reservoirs, often are repositories of untapped information and potential. Field X in particular stands as a testament to the enduring vitality of such mature assets. Even after decades of exploitation, it continues to demonstrate robust production potential, making it a remarkable case study within the industry. During the past 10 years, production in Field X has been primarily driven by the ATC reservoir, albeit at a reduced rate. This recent phase of extraction, aided by hydraulic fracturing, has revealed inefficiencies. Most notably, a lack of optimization in well spacing and hydraulic fracture design has been noted. Against this backdrop, this paper delves into the application of RTA in mature fields. The authors propose an innovative workflow that leverages historical data sources often overlooked, highlighting the transformative potential of RTA in reinvigorating development strategies for aging tight reservoirs. The goal is to understand, optimize, and revolutionize operational strategies in mature fields by use of a synergy between RTA, hydraulic fracturing, and simulation studies. Methodology Field X, encompassing approximately 100 producing wells spread across 22 distinct zones, initially tapped into 22 separate reservoirs, achieving a notable start of more than 10,000 STB/D. This study concentrates on the development of the northern area of Field X, specifically targeting the ATC reservoir. The focus is on exploiting tight oil reservoirs through the application of hydraulic fracturing techniques. To enhance the efficacy of these fracturing treatments, nodal analysis was used. The optimization process faced challenges, however, because of the uncertainties surrounding the drainage area and permeability characteristics of the ATC reservoir. In the authors’ approach, the drainage area was conservatively estimated to be half the well spacing. The permeability values were derived from porosity logs. This led to a wide permeability range of 0.5–5 md, introducing complexities in the fracture-optimization process. Post-fracturing, the wells exhibited production rates ranging between 100 and 200 STB/D, using sucker rod pumps (SRPs) for artificial lift. The production profiles showed a steep initial decline, stabilizing at approximately 50 BOPD over a 7-year period. This production behavior indicated substantial reserve potential.