Unconventionals Meets Deepwater; Lower Completion Limited Entry Liner with Retrievable Ball Drop Diversion System applied in a Deepwater Brazil Carbonate Field

Abstract

In order to economically develop the Albian Carbonate Macae formation in the Campos Basin Deepwater Brazil an extended reach horizontal well is required. Due to the tight nature (low permeability) of the rock, stimulation of the reservoir is required. Completion designs and techniques for treating extended reach horizontal wells in deepwater are limited. Most applications for these type wells in Deepwater are ineffective (high skin/low PI) and inefficient (trip/time intensive) affecting project economics. A completion system was developed that allows for safe, effective and efficient stimulation and installation of such an extended reach horizontal well in Deepwater. This paper will describe the design, testing and execution of a unique Deepwater completion system that adapts a known multi-stage ball drop system used in onshore unconventional reservoirs, for example the US and Canada, to a known horizontal open hole sand control system to effectively matrix acidize a 2000 m horizontal open hole thru a Limited Entry Liner with reservoir segmentation. The system uses a Retrievable Ball Drop Diversion System (RBDDS) consisting of multi-stage frac sleeves run on wash pipe. The RBDDS is run inside a limited entry liner that is segmented into stages or intervals by openhole programmable interventionless packers (Mendes et al. 2014) all run in a single trip and with no pipe manipulation required while stimulating. It furthermore leaves behind a robust lower completion system for the life of the field. This 2000 m lower completion system was successfully run in the Albian Carbonate reservoir and all stages treated with 15% HCl with minimal NPT, no harm to people or environment. At the time of completion, this well was the longest horizontal reservoir section and longest step out well drilled and completed in Brazil. This Limited Entry Liner System together with the RBDDS proved to be a very efficient, effective and deepwater friendly system. Introduction Low permeable deepwater carbonate reservoirs have created many challenges to produce economically. The wells typically require extensive reservoir contact that has to be stimulated in order to achieve an acceptable Productivity Index, PI. Field A, Albian Carbonate in the Campos basin offshore Brazil falls into this challenging category. Effectively stimulating long horizontals has long been an industry challenge onshore and even more so in a deepwater environment. With the advent of Unconventionals in the US and Canada the ability to stimulate long horizontals has generated a great deal of focus and effort over the last few years. The high rate and multi-stage fracture stimulations done on these wells has resulted in the development of new industry techniques, notably using frac sleeves operated by dropping balls, and pumping down plugs and perforating guns to isolate and perforate each stage. This paper will review the concept selection process, detailed design work, testing, and implementation results of an extended reach horizontal well that utilizes onshore Unconventional ball drop technology adapted to a Deepwater setting to effectively stimulation a 2000 m long horizontal section. The well and stimulation treatment was considered an apparaisal effort such that if the production from the well is suitable it will open up the full Albian Carbonate for further development.