No abstract

A development in deepwater off Western Africa has been experiencing incompatibility between the incumbent scale inhibitor and a newly deployed corrosion inhibitor. Initial laboratory testing to determine the amount of scale inhibitor necessary to overcome the interference from the corrosion inhibitor indicated that the effects of the corrosion inhibitor could not be overcome by increasing the dose of the scale inhibitor. Testing of other scale inhibitors indicated that there was not a suitable scale inhibitor that could inhibit scale formation in the presence of the corrosion inhibitor. That initial work was performed using synthetic brines that contained no acetate/acetic acid buffer to help control pH of the system. Further work evaluating the effect of buffering upon scale inhibitor performance employed brine containing an acetate/acetic acid buffer. Once this buffer solution was employed in static bottle testing, it was observed that an alternative scale inhibitor previously tested now worked in the presence of the corrosion inhibitor. While it is known that corrosion inhibitors can impact scale inhibitor performance the impact of organic acid on this interaction has not been published.Since the field where the chemicals were to be applied is known to contain organic acids (upwards of 2,000 ppm), the testing which included the acetate/acetic acid buffer is viewed as a more representative test for the field than the testing that did not contain any organic acids. A field trial of the alternative scale inhibitor and the corrosion inhibitor has been under taken. The paper will present the results from two field trials, the laboratory evaluation to understand the mechanism of interaction and selection of the alternative inhibitor chemical. This paper will shed light on the challenging subject of scale inhibitor and corrosion inhibitor interaction and review the most appropriate test methods/conditions to select non interfering chemicals.

It has been proven that scale squeezes can be conducted effectively in the unconventional, horizontal fractured wells in the shale reservoir of the Bakken when using an optimal scale squeeze chemistry. Previous work has discussed inhibitor selection and performance testing along with early case histories and modeling work. This paper discusses new case histories and Place-iT modeling results based on several procedural variations including a range of overflush volumes in the squeeze treatment procedure and the inclusion of acid cleanouts. Novel, reduced-volume squeeze designs have successfully protected wells from scale deposition while limiting the direct and indirect costs associated with extra placement water. For unconventional shale wells in the Bakken, where produced water is typically very high in TDS and TSS, fresh water is most commonly used to execute squeezes. Reducing the total water volume reduces the costs of purchasing, transporting and storing fresh water. The amount of time and cost to pump the job is decreased. Less time and money is spent lifting the placement water, and consequently, there is less deferred production. In addition, in unconventional production acid treatments are commonly carried out in isolation to maintain production. In this work, applying acidizing stages at the front of the squeeze procedures, provides a novel "squimulation" process to fractured reservoir scale control treatments. For these unconventional horizontal wells, the use of larger water volumes—either several times full wellbore volume and/or several times daily water production—has not been shown to improve the longevity or cost-effectiveness of squeeze jobs. Contrary to conventional well applications modeled with Darcy flow, it appears diffusion is the more applicable mechanism for scale inhibitor transport in fractured shale wells. This mechanism is consistent with a reduced dependence on water volume deployed in the treatments. The lessons learned from the unconventional horizontal scale squeezes conducted in the Bakken have resulted in enhanced production and cost savings. There are significant implications for the industry as other key unconventional regions in the U.S. and around the world are looking into scale squeezes as an option for scale control.

The development of unconventional basins across North America for the past decade initially caused some in the industry to wonder if challenges found in unconventional basins would require new chemistries and technologies. As the basins have been produced and water chemistries evaluated and treated, it has become clear that established scale inhibitor chemistries and methodologies are suitable to treat unconventional scaling scenarios. However, the number of applicable chemistries can be limited as some of the most common scale inhibitor chemistries have been found lacking in iron tolerance. The biggest lesson learned over the course of the past decade has been to not underestimate the role that iron can play as spoiler not only in performance of scale inhibitor chemistries, but also in test methodologies and monitoring techniques. While the need to account for iron in conventional programs has not been taken for granted, the amount of iron produced in unconventional production basins has led to a re-evaluation of just how severely iron in solution can impact scale programs from product testing and selection all the way through to program monitoring. This paper highlights the brine chemistries in major North American unconventional basins, especially regarding iron. Test methods and results from dynamic scale loop and anaerobic static bottle testing will be highlighted as well as the limitations of using field brines in product evaluations. Field observations will be discussed to support the importance of proper product selection as well as monitoring techniques. This subject has implications for the industry as unconventional basins across North America continue to search for program improvements to drive reductions in total operational costs. Additionally, as unconventional basins are developed outside of North America, the lessons learned can be applied to efficiently develop best in class scale inhibitor programs. As appreciation for the impact of high levels of iron on scale inhibitor performance continues to evolve, there is a possibility that a smaller amount of iron tolerant scale inhibitors will limit the treatment options available in unconventional production basins.

Разработка и применение ингибитора солевых отложений для погружных электроцентробежных насосов, подходящего для эксплуатации в условиях чрезвычайно холодной погоды Сандра Линарес-Саманиего и Кевин Спика, компания Nalco Авторское право 2010 г., Общество инженеров-нефтяников.Данный доклад был подготовлен для проведения презентации на Российской нефтегазовой технической конференции и выставке SPE 2010, которая пройдет в Москве (Россия) в период с 26 по 28 октября 2010 г.Данный доклад был выбран Программным комитетом SPE по результатам экспертизы информации, содержащейся в представленной автором(-ами) резюме. Экспертиза содержания доклада Обществом инженеров-нефтяников не выполнялась, и доклад подлежит внесению исправлений и корректировок автором(-ами). Материал в том виде, в котором он представлен, не обязательно отражает точку зрения Общества инженеров-нефтяников, его должностных лиц или участников. Электронное копирование, распространение или хранение любой части данного доклада без предварительного письменного согласия Общества инженеров-нефтяников запрещается. Разрешение на воспроизведение в печатном виде распространяется только на резюме длиной не более 300 слов; при этом копировать иллюстрации не разрешается. Резюме должно содержать явно выраженную ссылку на то, где и кем был представлен данный доклад.