Strategy and Planing EOR for Caracara Sur Field, Colombia

Abstract

The Caracara Sur Field (Llanos Basin, Colombia) consists of multilayered compartmentalized fluviodeltaic reservoirs. Sands have Darcy-level permeability, contain a medium-quality oil (21° API), and are subject to very strong aquifer support. The reservoirs are produced with artificial lift, either selectively or commingled. After six years of development, oil production is expected to decline. Ongoing efforts to maintain the production plateau include infill and horizontal attic oil drilling and selective completions. However, there is a limit to what can be achieved considering the strong aquifer drive and unfavourable mobility ratio. This encouraged the investigation of enhanced/increased oil recovery (EOR/IOR) methods which has resulted in screening a number of EOR processes and the planning of a pilot project in the field. EOR/IOR screening evaluation identified chemical EOR processes as the most suitable techniques for the field. Polymer, alkaline-polymer (AP), Alkaline-Surfactant-Polymer (ASP) and surfactant-polymer (SP) are the technologies under consideration. A careful and complete project plan has been developed, customized for the field’s most challenging characteristics: fresh formation water, in-situ oil viscosity of 12 cP, relatively high reservoir temperature (above 175 °F), the need to inject and produce commingled, (up to six stacked reservoirs) and most importantly the strong and drifting aquifer, which is expected to influence sweep efficiency. The plan includes laboratory studies, multi-scale high-resolution reservoir simulation, single-layer single-well tests of injectivity and residual oil saturation, and a multi-layer inter-well pilot prior to full-field deployment. Tracer technology has been developed in-house to support the project. Back flow tracer tests and single-well tracer tests will be conducted in the field to evaluate aquifer drift and to determine the remaining oil saturation. Comprehensive evaluation will permit the design of an efficient vertical injection profile, appropriate injectivity and chemicals displacement in a multi-reservoir field. The planning stage of the Caracara Sur EOR strategy, including the screening evaluation and the first project results, provides guidelines and solutions that can be used on other EOR projects in similar fields and facing similar challenges, not only within the Caracara Block itself, but within the Llanos Basin and elsewhere: A ‘fast-track’ program, whereby screening and field studies are done partly in parallel targetting shortened elapsed time for the pilot evaluation. If results are technically successful this will allow profitable full-field EOR implementation. Use of an in-house project team supported by integrated laboratory expertise (leveraging CEPSA’s petrochemicals experience) is proving to be efficient and successful in delivering a high quality technical solution.

A comprehensive review of alkaline–surfactant–polymer (ASP) flooding

“…Mangala was reported to have an ASP project . The EOR studies on the Caracara Sur field in Llanos Basin, Columbia were conducted, but a field pilot or an application has not been seen reported. Several papers have been presented about the design and preparation of the offshore ASP pilots in two fields, St. Joseph in Malaysia and La Salina in Venezuela .…”

Essentials of Upscaling Surfactants for EOR Field Projects

“…ASP or SP is a logical extension and has the promise to liberate the trapped oil. Consequently, there are several pattern-flood pilots in progress or about to be executed to evaluate ASP at a scale relevant to commercial scale application [14][15][16][17][18][19][20][21][22].…”

Strategy for Calibrating a Field-Scale Numerical Simulation Study for the Implementation of a Chemical Enhanced Oil Recovery Pilot Using Core Flooding and Pre-Pilot Experiments

“…Full understanding of the performance of the ASP process and the relevant mechanisms of ASPformation interaction is challenging, especially for the CCS reservoirs with its own unique characteristics and uncertainties (Cubillos et al 2013). Challenges are associated to uncertainties related to the original oil in place, fluid saturation distribution, lateral connectivity, aquifer connections & strengths and the residual oil saturation estimation.…”