Managing severe-to-total lost circulation can be especially challenging in naturally fractured formations. This situation becomes further complicated if it is a producing formation. Particulate lost circulation materials (LCM) have been used to manage lost circulation for many years. However, current LCMs are not efficient in terms of size and application methods to cure severe-to-total losses, such as highly fractured reservoirs.

In the present paper, a novel acid-soluble combination in the form of an engineered composite LCM solution (ECS) with a multi-modal particle size distribution (PSD) has the potential to manage severe-to-total loss circulation situations in naturally fractured reservoir formations. The multi-modal PSD and unique combination of particles will help manage any uncertainties in fracture sizes, and the larger particles present will aid in plugging large fractures. The results of a laboratory investigation will be presented, highlighting the potential benefits of this solution.

When managing severe-to-total losses in highly fractured reservoir formations, particulates alone may not be effective, thus the LCM should preferably be acid soluble. The combination of a large multi-modal PSD LCM containing a fibrous material along with platelet particles was designed as a candidate for dealing with these extreme losses. The solution developed is capable of plugging laboratory-simulated fracture sizes in the range of 5,000 μm. It was further demonstrated that supplementing with another larger LCM platelet materials enhanced its capability to seal 0.5 in. (12.5 mm) in the lab. A significant determination in the solution developed is up to 96% soluble in 15% HCl and organic acids. This paper will discuss in detail the product concentration, testing methodology, and results. In addition, the strategy to apply these materials in the field will be discussed.

The large PSD, acid-soluble LCM solution can help manage uncertainties in fracture sizes and allow for curing severe-to-total losses in naturally fractured reservoir formations.

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