A comparative study of fishbones technology and hydraulic fractures in a tight carbonate reservoir using EDFM : field case application
Creators: name: Lliteras Popoca, David Orlando
name: 0000-0002-0644-9322
Publisher: name: The University of Texas at Austin
Year: 2022
Subjects: Multilateral stimulation technology
Fishbones technology

description: The oil and gas industry is among the world’s most capital-intensive sectors. Oil and gas companies are constantly innovating and in search of new technology to increase oil production of current and new field prospects. A recent multilateral stimulation technology, named Fishbones technology designed to improve reservoir stimulation, has gained attention in recent years aiming to boost hydrocarbon production. In addition to offering competitive price, target selectivity, productivity of fracturing and reduced operation time compared with hydraulic fractures, Fishbones technology has the advantage of keeping the flow laterals open, being unsusceptible to closure during production time. Here, we present the first reservoir-simulation studies to compare Fishbones technology to hydraulic fracture completions with the goal of evaluating the advantages and disadvantages and to provide practical recommendations before field implementation. Using a refined sector model extracted from a tight carbonate reservoir in onshore, Mexico, we build simulation models under a wide range of possibilities. The permeability of the reservoir is in the range 0.1-12 md and the studied field has 10 vertical wells that produce gas and condensate and 15 new prospective wells. We place the hydraulic fractures and fishbones laterals using an adaptation of the non-intrusive Embedded Discrete Fracture Model (EDFM) method, originally developed to model conductive faults and fractures, in conjunction with a commercial reservoir simulator to evaluate the well performance and propose the best technical/economic option. We first validate our model against field data, including a registered 650% improvement in condensate rate after acid hydraulic-fracturing treatment. A sensitivity evaluation is performed by varying the reservoir properties, fishbones laterals geometry (length, deployed angle, lateral spacing), different hydraulic fracture geometries, additional parameters, and adding the field natural fracture network. Results show a slightly larger cumulative condensate production after utilizing 11 fishbones subs (44 fishbones laterals with 40-ft length and ½ inch diameter) compared to the implemented hydraulic fractures (226-ft length) in the already producing well. Fishbones laterals demonstrated a superior performance over a hydraulic fracture in reservoirs matrix permeability larger than 1 millidarcy, for well-connected natural fractures networks and in reservoirs with a defined water contact. Natural fractures orientation allows a greater number of laterals-fracture connections, increasing the fracture network and the cumulative hydrocarbon production. We determined it requires hydraulic fractures with at least 100 md-ft conductivity and 80 ft half-length to attain enhancement in production equivalent to that of the fishbone’s laterals. Such requirements in fractures are generally not maintained, because even if the initial conductivity is large, the fractures typically lose conductivity due to closure effects as the wells flow back and the pressure depletes. We explain that Fishbones technology provide considerably greater conductivity than hydraulic fractures, which is proven to be advantageous for long-term recovery. As the permeability of the reservoir decreases, however, the favorability of hydraulic fractures increases, owing to the increased contacted surface area, which becomes increasingly important at smaller permeability.Findings suggest an improved performance of hydraulic fractures in unfractured reservoirs, low reservoir anisotropy and in well-spacing larger than 1,000 ft. According to an extensive literature survey, we found no studies in the literature that assessed the Fishbones technology against hydraulic fracturing in presence of a natural fracture network. In our study, we provide recommendations on the advantages and disadvantages of the two completion techniques and the lessons learned from the application at a specific area of interest. The Fishbones technology scenario resulted in a more positive economic outcome, according to a deterministic net present value assessment, which may support the use of Fishbones technology in this new development field. The evolution and future implementation of this technology in the studied area will provide additional data to optimize both completions design and field development strategies.