The term mixed scale pertains to the scales found in oil and gas production system containing both organic and inorganic constituents in such a way that either aqueous-based inorganic dissolver or solvent-based organic dissolver fails to act on it. These scales are also known as wetted scales. This research discovers formulations which can effectively dissolve and disperse mixed scales dominated by inorganic content. Micro-emulsion-based solutions are identified as the best in tackling such mixed scales. A few inorganic and organic dissolving chemicals along with surfactants and co-surfactants are considered in this research to develop environment friendly solutions. The stable micro-emulsions are subjected to detailed dissolution study to establish their efficacy. The synthesized chemical solutions are shown to dissolve mixed scales of different composition. A chelant-based micro-emulsion formulation is also found to be effective in dissolving difficult to treat metal naphthenate scales co-precipitated with organic content, which is a novel application.
Scale control during Alkaline Surfactant Polymer (ASP) flooding is a recognised challenge especially following ASP breakthrough at the production wells, due to continual mixing of the high pH ASP waters with reservoir brine. The effective performance of scale inhibitors (SIs) is a problem, given the high oversaturation expected due to mixing of injected alkali and formation water. Previous work (SPE 141551) described this challenge for a conventional system whereby ASP was injected into a reservoir containing low salinity / low divalent ion Formation Water (FW). This work showed that chemical performance (SI/ brine compatibility and performance) could be achieved using conventional inhibitors and that treatment of the production wells via downhole squeeze treatments was achievable. It also demonstrated that the production of high pH ASP fluids had a considerable impact on the retention and release properties of the chemicals. This paper progresses significantly from the previous work by examining a field case study. Although the formation water is a low salinity / low divalent cation brine similar to that in the earlier example, this field represents a considerably more severe scaling challenge since it has already been flooded with Sea Water (SW). The SW contains considerably higher divalent cation concentrations (c.f. Ca2+ ~ 450mg/l vs. ~40 mg/l for the formation water) and results in a considerably more severe challenge in terms of SI/Brine compatibility and chemical performance when examining a range of conventional SI's. The paper describes extensive modeling of the in situ conditions for this field following ASP flooding, extensive scale inhibitor performance tests across a wide range of conditions and mixtures of ASP/FW/SW together with a series of core flood tests to assess the potential for squeeze treatments in this new pilot ASP system. For the pilot, reservoir modelling was essential to simulate the expected mixture of ASP/FW/SW which would be produced, such that chemicals could be targeted for the expected produced mixtures (Note: increased FW:SW ratio results in more achievable inhibition) allowing chemical selection for squeeze. The pilot ASP flood in this field is now planned for 2014.
The studies involves several unique case for EOR fields in which crude oil samples were collected from from peninsular Malaysia and Borneo. These fields has different reservoir characteristic in pressure, temperature and gas composition. Five Crude Oil from EOR field were undergone Naphthenate acid extraction using acid IER techniques for further instrument analysis to classification of Naphthenate acid type's component. Comparison of soaps-microemulsion generated was then analyse using static bottle test and Naphthenates/Emulsions Flow Rig Tests. The findings shows the Malaysian crude oil is able to be classified by type of naphthenate acid which are mono-protic acid generating sodium carboxylate soap and tetraprotic acid known as ARN which leads to calcium naphthenate deposit. There are fields that located nearby each other has different characterization of crude and types of acids which leads to different type and severities of soaps-microemulsion and soaps-fines foams formation from apllied EOR chemical. Statics bottle test at higher water cuts shows significant differences with observation from Naphthenates/Emulsions Flow Rig Tests. From this paper classification of Naphthenate acid for Malaysian crude oil has been established with its behavior to induce Soaps-Microemulsion and Soap-Fines Foam in Malaysian EOR Fields using more representive method by Naphthenates/Emulsions Flow Rig Tests.
The injection of sea water for the pressure support of oil fields is commonly associated with the biogeneration of hydrogen sulfide (H2S) by sulfate reducing bacteria and/or archaea (SRB/SRA). H2S is extremely toxic and corrosive, as well as providing a source of sulfide ions for the formation of iron, zinc and/or lead sulfide scale. However, H2S production is rarely, if ever, associated with seawater breakthrough and its retardation can be linked to a number of mechanisms. Certain minerals (e.g. siderite, FeCO3, and/or iron oxides, FexOy) may react with produced H2S and retard its progress towards the producer wells. This is a generally beneficial effect but it is difficult to quantify and it is generally estimated from direct matching to the field appearance of H2S. Alternatively, H2S retardation factors are based on correlations with the mineralogy of the field and these are rather unreliable, since few experimental results have been published. In essence, this quantity (the H2S retardation factor) is more of a "matching parameter" rather than being truly predictive. Candidate mechanisms for sulfide scavenging by iron-bearing minerals have been experimentally identified and scavenging capacities have been determined for siderite FeCO3 in modified static adsorption tests and in dynamic pack floods, for aqueous-only systems. The effects of changing several conditions were studied, including temperature, initial pH and grain size. A combination of dissolution/precipitation and surface displacement mechanisms were identified in the static bottle tests and further confirmed during the dynamic sand/siderite and crushed-core pack floods. ESEM-EDX and particle size analyses established the presence of mobile FeS (<100 µm) in the column after the flood had reached completion, confirming the bulk precipitation of FeS from dissolved Fe2+. Bringing together these two mechanisms allowed for the rationalisation of the observed scavenging profile, with reference to the Ksp of siderite. By further understanding the mechanisms of H2S scavenging experimentally, it will be possible to incorporate these into field-prediction models. The absolute values obtained for the 8 wt% siderite packs were 1.03 and 1.74 mg/g at 25 and 96°C, respectively. Crushed core packs yielded significantly higher values of 5.76 and 5.80 mg/g at 25 and 96°C, respectively, which have been hypothetically attributed to the presence of iron-bearing clays in the core samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.