Offshore Oil Recovery Research Articles

Response Options for an Offshore Deepwater Blow-Out, A Generic Evaluation of Individual and Combined Response Strategies

Abstract The low oil recovery rates reported during Macondo (3–5% of the released oil) have caused discussions regarding the efficiency of mechanical recovery compared to other oil spill response options. These low recovery rates have unfortunately been used as reference recovery rates in several later modelling studies and oil spill response analysis. Multiple factors could explain these low rates, such as operational priorities, where dispersants and/or in situ burning are given priority before mechanical recovery; extended safety zones; availability of adequate equipment and storage capacity of collected oil; the number of units available; the level of training and the available remote sensing support to guide operations. This study uses the OSCAR oil spill model to simulate a deep-water oil release to evaluate the effect of different response options both separately and in combination. The evaluated response options are subsea dispersant injection, mechanical recovery, and a combination of these. As expected, Subsea Dispersant Injection (SSDI) was highly effective and resulted in a significant reduction in residual surface oil (8% of released oil volume, versus 28% for the non-response option, NR). However, using large offshore oil recovery systems also reduced residual surface oil with a similar amount (9% of released oil volume). These results deviate significantly from the efficiency numbers reported after the Macondo incident and from later modelling studies scaled after the Macondo recovery rates. The increased efficiency of mechanical reported in this study is mainly due to inclusion of updated descriptions of response capabilities, reduced exclusion zone, a more realistic representation of surface oil distribution and modelling of response units' interactions with oil, (efficient oil recovery only on thick parts of the oil slick). The response capabilities and efficiency numbers for the different response options used in this study are based on equipment specifications from multiple response providers and authorities (Norwegian Clean Seas organisation (NOFO), Oil Spill Response (OSRL), Norwegian Coastal Administration (NCA), US Bureau of Safety and Environmental Enforcement (BSEE) and others). These capabilities are justified by well-established contingency plans, offshore exercises and annual equipment performance testing with oil.

Natural Dumpflood in Malaysia Succeeds as Low-Cost Offshore Oil-Recovery Method

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 196498, “First Natural Dumpflood in Malaysia: A Successful Breakthrough for Maximizing Oil Recovery in an Offshore Environment With Low-Cost Secondary Recovery,” by Muhammad Abdulhadi, SPE, Toan Van Tran, SPE, and Najmi Mansor, Dialog Group, et al., prepared for the 2019 SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition, Bali, Indonesia, 29–31 October. The paper has not been peer reviewed. The complete paper describes the first successful implementation of natural dumpflooding offshore Malaysia as a case study to provide insight into the value of using the approach to maximize oil recovery in a mature field, particularly in a low-margin business climate. Background Field B, located offshore Balingian province approximately 80 km northwest of Bintulu, has a water depth of 90 ft and is highly compartmentalized and faulted, with almost 100 faults present. The field features three subfields further divided into nine major fault compartments. Eight primary reservoirs exist, with more than 20 subreservoirs stacked atop one another with multiple drive mechanisms, including water drive, gas-cap drive, and solution gas drive. Several of these subreservoirs are thick sands between which communication exists through juxtapositions, shared gas caps, or aquifer. Other subreservoirs are isolated by thin layers of shale apparent in certain wells but absent in others. The high complexity of Field B requires any opportunity identified to be thoroughly evaluated and examined before execution. Field B is a moderately sized field discovered in 1976, with production commencing in 1984. During the 30 years of oil production, the field peaked at 30,000 B/D in 1990 and dipped to 3,000 B/D in late 1999. The facilities consist of four drilling platforms, a processing platform, and a compressor platform. A total of 48 wells were drilled in the field, with most wells completed as dual-string producers. The recovery factor (RF) of the reservoirs ranges from 10% for solution gas drive to 50% for strong water drive. The behaviors of these reservoirs are starkly different. The solution gas-drive reservoirs have poor-quality sand (less than 200 md), a low productivity index, limited sand thickness (less than 30 ft), limited sand connectivity, and sharp pressure decline after 2 to 3 years of production. The water-drive reservoirs, however, have good-quality sand (up to 5,000 md), a high productivity index, thick sand (greater than 40 ft), extensive sand connectivity, and limited pressure decline. The stark differences in the reservoirs’ behavior further complicate field management. The field currently is in late life, with recovery to date of 19% with an RF of 23%. Most of the water-drive reservoirs are already swept up to the crest, while the solution gas-drive reservoirs are depleted nearly to abandonment pressure. After 30 years of production, the total field water cut was at 80%, while oil production was approximately 5,000 B/D, signifying the diminishing economic life of the field.

Improved oil recovery sensor

A new type of sensor was developed to measure oil content in seawater or other highly saline waters for offshore oil spill recovery operations. Currently responders do not have a quantitative method for knowing in real time how much water they are collecting with their oil. The sensor combines two measurement principles: a dielectric measurement and an eddy current loss measurement. The dielectric measurement is used for high oil content mixtures and emulsions that are of water-in-oil type, leading to a relatively low electrical conductivity. The eddy current measurement is used for low oil content mixtures and emulsions, that are of oil-in-water type, and have high electrical conductivity. Both measurements are carried out at high frequencies, in the 10–50 MHz range, which makes the measurement insensitive to the type of oil and its dispersion, as well as polarization effects, while maintaining sufficiently large skin penetration depths. The sensor was demonstrated in laboratory tests as well as at the Bureau of Safety and Environmental Enforcement’s (BSEE’s) Ohmsett testing facility using mixtures of several crude and refined oils with water salinities in the 1–5% range. In all cases, the sensor provided a reliable oil content measurement with average errors of about 3% in a laboratory setting and about 7% during Ohmsett testing, which is sufficient for offshore oil recovery operations. Having this information will allow a responder to make on-the-spot adjustments to maximize recovery efficiency. In addition, the sensor will provide data on overall oil/water collection during a response. Other uses include oil and gas industry applications, where oil-water mixtures need to be evaluated for oil content or, equivalently, for water cut, and where high-water salinity prevents use of traditional sensors based on the dielectric principle alone.

ANALYTICAL SOLUTION FOR A LONG WAVES PROPAGATION IN TWO-LAYER FLUID OVER A SUBMERGED HUMP

The study of internal waves has become important because they are associated with the energytransfer mechanism across continental shelf edges. In addition, they also can cause strong localizeddepartures from the surrounding ocean conditions, resulting in increased shear stresses on underwaterstructures and large variations in acoustic transmission properties of the ocean. Therefore, the internal wavescause problems in many areas such as offshore oil recovery, acoustic propagation in the ocean, and deepwater outfall. Hence, this paper is conducted to study the two-layer long-waves propagation throughsubmerged humps using analytical solution. Equation involved in this study are mild slope equation and themethods involve are separation of variables and a series solution. In this study the effect of the geometry ofthe hump when water waves propagating through the humps are also studied. Besides, the density ratio alsogive significance effect to the surface wave elevation. An analytical solutions obtained in this study is usefulin reviewing applications and condition of the wave amplitude on submerged hump.

Bisulfite reductase and nitrogenase genes retrieved from biocorrosive bacteria in saline produced waters of offshore oil recovery facilities

Water-flooding is a common strategy to enhance oil recovery in reservoirs. Maintaining quality and standards of produced water avoids oil biodegradation, biogenic souring and biocorrosion during operations, which are influenced by sulfate-reducing (SRB) and Fe (III) reducing bacteria. The aim of this work was to increase our knowledge of corrosive bacterial communities inhabiting saline produced waters of offshore oil exploitation facilities through retrieving sequences of functional genes, for instance, dsrAB and nifD of Desulfovibrionales, Desulfobacterales and Desulfuromonadales taxonomical orders. Five clone libraries were generated with retrieved sequences acquired from different saline produced waters, with and without biocide dosing. The dsrAB phylogenetic analyses showed Desulfomicrobium, Desulfovibrio, and Desulfohalobium as well as Desulfococcus, Desulfosarcina, Desulfobacter, Desulfobacterium and Desulfobulbus. The retrieved nifD genes displayed the Fe (III) reducing bacteria (Desulfuromonadales) such as Desulfuromusa, Pelobacter, Malonomonas, and Desulfuromonas. The relative abundance in all waters was: the Desulfovibrionales were represented by 55.28% of analyzed clones; the Desulfobacterales by 26.83% and 17.89% for the Desulfuromonadales. Diversity measures were calculated by the Shannon index (H′), which showed that there was a high degree of diversity between all produced waters; however, dominance in produced water with biocide was detected by a Desulfovibrio taxon.

Complete genome sequence of Denitrovibrio acetiphilus type strain (N2460T)

Denitrovibrio acetiphilus Myhr and Torsvik 2000 is the type species of the genus Denitrovibrio in the bacterial family Deferribacteraceae. It is of phylogenetic interest because there are only six genera described in the family Deferribacteraceae. D. acetiphilus was isolated as a representative of a population reducing nitrate to ammonia in a laboratory column simulating the conditions in off-shore oil recovery fields. When nitrate was added to this column undesirable hydrogen sulfide production was stopped because the sulfate reducing populations were superseded by these nitrate reducing bacteria. Here we describe the features of this marine, mesophilic, obligately anaerobic organism respiring by nitrate reduction, together with the complete genome sequence, and annotation. This is the second complete genome sequence of the order Deferribacterales and the class Deferribacteres, which is the sole class in the phylum Deferribacteres. The 3,222,077 bp genome with its 3,034 protein-coding and 51 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.

The northern sea route today

1. 1. Outline of typical recent season's operations; freighting pattern, equipment employed, length of season. 2. 2. Current uses for the route: routine resupply, including to some inland areas; bringing out raw materials (minerals, timber); bringing in fuel and manufactured goods, including river craft; absence of significant through traffic. 3. 3. Future prospects: greater use for resupply, including to inland areas where routes from the south cannot be expanded; enlarging through traffic; possibility of year-round navigation; prospects in the central polar basin opened by Arktika voyage to North Pole in 1977; importance for offshore oil recovery in Kara Sea; possible effect of change in ice conditions, arising either naturally or through change in river run-of.

AN OFFSHORE MECHANIZED SORBENT OIL RECOVERY SYSTEM USING VESSELS OF OPPORTUNITY

ABSTRACT An experimental prototype offshore oil recovery system for use on vessels of opportunity has been developed by the Civil Engineering Laboratory under the sponsorship of the Navy's Supervisor of Salvage. The system is based on the concept of mechanized broadcasting, harvesting and recycling of polyurethane sorbent chips. A two-component, drop-type sorbent broadcaster was designed to uniformly distribute the sorbent in the high wind and wave conditions expected in the open ocean. Theoretical analyses of vessel motion indicated the harvester can be rigidly mounted to a barge-type vessel but that at least vertical articulation is required when mounted on an offshore work boat. The experimental prototype was functionally tested at sea without oil. The tests indicated that the waves and surface currents generated by the vessel can increase the interaction between the sorbent and the oil and enhance the sorption process. The tests also aided in identifying the characteristics of the sorbent required for use in a system of this type.