The Cerro Dragon (CD) Field, located in the San Jorge Gulf Basin (SJGB) of Argentina, offers a significant opportunity for improved volumetric sweep efficiency because of an adverse mobility ratio and spatial anisotropy, typical of the multilayered channels deposits of SJGB. The center of these channels becomes a highly conductive "thief zone", resulting in preferential channeling of injected water to the offset producers without creating an oil bank. As a consequence, sweep efficiency is reduced and operating costs are increased due to the handling of large volumes of produced water. These thief zones are the target for improved reservoir conformance using a thermally activated particle technology known as BrightWater® (BW), developed and patented by BP, Chevron and Nalco Company.
Testing of deep reservoir conformance in Argentina utilizing the BW technology began in 2006 with pilots in the Piedra Clavada and Koluel Kaike fields (Mustoni, et al., 2010). Screening, design and implementation of the BW conformance project in the CD Field was the result of experience gained from these earlier applications. The CD Field conformance project represents a larger scale application of the BW technology in terms of number of wells treated, layers per well, oil reserves, and treatment volumes.
This paper describes the methodology utilized to evaluate and rank BW conformance candidates from a database of more than 100 blocks in the CD Field. A detailed discussion of the candidate selection methodology will be presented, including laboratory testing, chemical formulation and volumes, well surveillance, inter-well tracer, and simulation studies.
This paper will also describe details of internally developed processes that optimized the logistics of field implementation, including simultaneous injection of the chemical solution in multiple injection wells and multiple subsurface mandrels.