Posts tagged CHEMICAL SYSTEMS ENGINEERING
Bacterial Monitoring & Remediation in Pipelines

Bacteria inhabit the vast majority of oilfield water systems. These may either be attached to the pipe wall (i.e. sessile bacteria) or free floating through the system (i.e. planktonic bacteria). Planktonic bacteria do not directly contribute to the microbiologically induced corrosion (MIC) of pipeline systems; however, planktonic bacteria can attach to the pipe wall under the right conditions, becoming sessile bacteria. Consequently, there is some value in monitoring planktonic bacteria activity in a pipeline, although it is substantially less beneficial than monitoring the sessile population activity.

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Functionality Testing of Production Chemicals For Deepwater

Efficient production of oil and gas generally requires the use of specialty chemicals to ensure continuous and profitable system operability. The application of these chemicals help mitigate several flow assurance and integrity related challenges including asphaltene and wax deposition, scale build-up, hydrate blockage, corrosion, etc. In offshore applications, particularly in deepwater (DW), where many components of the production system are not easily accessible, it is critical to ensure safe and reliable chemical delivery to obtain maximum recovery without any lost production or asset integrity issues.

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Corrosion Modeling: Comparison, Interpretation & Limitation

Corrosion modeling is a vital tool in the pre-Front End Engineering Design (pre-FEED), FEED, and operational stages of the life of pipeline and equipment systems. Corrosion and materials engineers often rely on corrosion prediction models to select appropriate materials for construction, incorporate sufficient corrosion allowance into a design, and evaluate chemical corrosion inhibitor requirements or recommend other corrosion mitigation methods.

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Subsea Chemical Cleanliness Specifications

Operators and chemical vendors responsible for chemical delivery to subsea developments are aware that the use of chemicals with unacceptable solids loadings can result in the plugging of injection lines, subsea metering systems, subsea connectors, and downhole injection locations. However, there is relatively little agreement across the industry regarding the exact chemical cleanliness specifications that need to be applied.

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Revised Gulf of Mexico Produced Water Discharge Requirements

The objective of this article is to summarize the main requirements of the permit, identify changes from the previous permit, and call out edits between the draft and final issue of the permit as these pertain to the discharge of produced waters and other treated waters from offshore production and water injection facilities.

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Axial Mixing in Pipe Displacement

It is frequently necessary to displace the contents of a pipeline or umbilical tube (fluid B) with another fluid (fluid A). If we don’t use a pig to separate the liquids, there will be mixing at the interface (axial mixing). The mixing zone requires us to over flush the line to effectively remove fluid B from the line. Below, we address a method of calculating the length of the mixing zone in order to determine the effective overflush requirement for a given pipeline or umbilical tube.

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Water Soluble Organics: Definitions & Removal Methods

Produced water overboard discharge is permitted in much of the world, but is subject to discharge limits. In the Gulf of Mexico (GoM), oil and grease (O&G) in produced water is limited to 29 mg/l average and 42 mg/l for excursions. Similar limits are in place in much of the rest of the world. O&G consists mainly of dispersed organics, but some organics dissolve in water in measurable concentrations. Produced water separation systems focus on removing dispersed oil via gravity-based separation methods. These work effectively on dispersed, O&G; however, these systems do not effectively remove water soluble organics (WSOs). Where WSOs exist in concentrations greater than 29 mg/l, conventional produced water treating systems cannot achieve GoM overboard discharge limits.

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Methanol in Produced Water Discharge

Methanol (MeOH) is widely used in multiple applications in the offshore oil and gas industry. It is typical practice for offshore oil production facilities to treat and dispose of produced water via overboard discharge, making MeOH one of the highest volume discharges of production-treating chemicals. Considering the significant volumes and concentrations described above, it becomes necessary for every asset to consider the environmental effects of MeOH overboard discharge and to assess appropriate mitigation strategies, as required.

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Hydrates: Prediction, Mitigation & Remediation Techniques

Hydrates and hydrate plugs can restrict flow, damage equipment, and potentially jeopardize the safety of personnel. Hydrates are formed as a result of the bond between gas and water molecules that occur at high-pressure, low-temperature environments. In deepwater, hydrates can form at temperatures higher than the ambient seabed temperature; hence, prevention and remediation of hydrates is a serious concern for deepwater operators.

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Produced Water Polishing

Produced water systems can be divided into 3 parts including primary, secondary, and polishing, as shown in Figure 1. In earlier GATEKEEPERs, the primary and secondary stages were discussed. Primary treatment is typically done via hydrocyclones or sometimes skim tanks. Secondary treatment is typically done via flotation units. Effluent from the second stage generally meets overboard discharge requirements and the polishing stage is typically not needed.

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