Open hole (OH) completions are not very common in the GoM, but the area has seen an uptick in OH wells in recent years, and a few big projects have elected to use the same completion archetype. There are several different ways to complete an OH well, and one of these completion techniques involves running screens across the OH in Drill-In fluid (DIF), displacing the DIF out of the OH with brine, and then setting the packer, before pumping a filter cake breaker, designed to remove the filter cake and restore the reservoir permeability to near pre-drilling levels.
A review of past open hole (OH) well completions in GoM revealed that there was an inconsistent action of the breaker on the filter-cake: sometimes the breaker would react quickly, and sometimes there was no noticeable effect. This study led to the development of a new technology to allow better displacements of the OH, with the ultimate objective of reducing initial well skin induced by the drill-in fluid (DIF) and filter cake.
It was theorized that the low displacement rates would lead to poor removal of the mud from the OH, in turn leading to a poor breaker action on the DIF filter cake and a long-term impact on well injectivity and increased OPEX, as these wells tend to need an initial stimulation within a short timeframe after initial completion. The approach used was to develop a new tool to allow faster displacement rates, and test it on a trial well, to verify the results and validate this theory.
To solve this problem, a new tool was proposed, developed and fully tested in a tight deadline of 6 months. The new module allows up to 9 bpm rates and up to 3,500 psi differential pressure before setting the packer, versus the previous ∼800 psi differential pressure limit, present in all tools in the market, for that casing size (7 5/8").
During the first well trial, the tool allowed a displacement of the OH at double the pump rates obtained in previous wells in the same basin, with similar OH lengths, leading to the smallest volume of contaminated fluid interface seen to date, indicating a much better displacement. Once the well was put online, it achieved an injection rate above expectations, even when the drilled OH interval penetrated significantly less net sands than originally planned. The results on this single well trial seem to corroborate the theory posed, however it is recognized that more data is required to be certain of its results, and that will only come with time, as well performance is measured and compared with other wells that did not use the same technology.
The novelty of this new technology is the ability to obtain a better displacement of the OH, leading to a better breaker action and well cleanup in OH completions. Although the trial well was an injector well, the technology is equally applicable to producer wells. The paper will cover the problem description, installation procedures, development and testing of the technology, design aspects of using the technology and the successful implementation in the trial well.
