Scale deposition down hole is a well-known and common production problem throughout the industry. Successful treatment of scale where it is first deposited near wellbore can be challenging in many cases, and sometimes impossible in others. While production assurance and scale inhibition chemicals have traditionally been added as a liquid in the fracturing fluid, this approach is often not very efficient or effective as a standalone inhibition strategy. Quite often a significant fraction of the chemical immediately returns during the initial flow back with only a small portion remaining for future inhibition. This then typically necessitates reapplication of the inhibitor chemicals using a squeeze treatment or continuous injection.
The chemical delivery system described here utilizes porous ceramic proppant, which has been infused with the appropriate production chemical(s) and encapsulated. The infused ceramic proppant is added at a designed small weight fraction to the rest of the proppant volume in the fracture treatment. It is manufactured to perform as both a proppant and a chemical delivery system so it replaces an equivalent volume of standard proppant in its dual function as a proppant [Duenckel, 2014]. After placement in the fracture the chemical slowly releases from the proppant over the designed treatment period. This chemical delivery system allows for a large amount of chemical to be placed within the fracture, releasing slowly, without negatively impacting conductivity. The proppant is encapsulated with a semipermeable membrane which controls the release of production chemicals during placement and production. This provides long term scale protection and production assurance which eliminates the need for additional costly well treatments and lowers overall lease operating expense.
In addition to describing the chemical delivery system, this paper will present a case history in which five wells in the Uinta Basin were treated with scale inhibitor using this new delivery system. In this application the infused porous ceramic was added in at a design fraction to natural frac sand treatments. Inhibitor returns will be presented which illustrate the efficient, long term protection of the entire production system from both barium sulfate and calcium carbonate scale.
This paper will be useful for all production and completions engineers and technicians who are engaged in providing long term scale prevention and production assurance.
Author(s): Joshua G. Leasure: CARBO Ceramics Inc., Robert J. Duenckel: CARBO Ceramics Inc., Jeff Hebert: CARBO Ceramics Inc.
Paper Number: SPE-173792-MS