Geothermal Gradient And Heat Flow Maps Of Offshore Malaysia: Some Updates And Observations

An update of the geothermal gradient and heat flow maps for offshore Malaysia based on oil and gas industry data is long overdue. In this article we present an update based on available data and information compiled from PETRONAS and operator archives. More than 600 new datapoints calculated from bottom-hole temperature (BHT) data from oil and gas wells were added to the compilation, along with 165 datapoints from heat flow probe measurements at the seabed in the deep-water areas off Sarawak and Sabah. The heat flow probe surveys also provided direct measurements of seabed sediment thermal conductivity. For the calculation of heat flows from the BHT-based temperature gradients, empirical relationships between sediment thermal conductivity and burial depth were derived from thermal conductivity measurements of core samples in oil/gas wells (in the Malay Basin) and from ODP and IODP drillholes (as analogues for Sarawak and Sabah basins). The results of this study further enhanced our insights into the similarities and differences between the various basins and their relationships to tectonic settings. The Malay Basin has relatively high geothermal gradients (average ~47 °C/km). Higher gradients in the basin centre are attributed to crustal thinning due to extension. The Sarawak Basin has similar above-average geothermal gradients (~45 °C/km), whereas the Baram Delta area and the Sabah Shelf have considerably lower gradients (~29 to ~34 °C/km). These differences are attributed to the underlying tectonic settings; the Sarawak Shelf, like the Malay Basin, is underlain by an extensional terrane, whereas the Sabah Basin and Baram Delta east of the West Baram Line are underlain by a former collisional margin (between Dangerous Grounds rifted terrane and Sabah). The deep-water areas off Sarawak and Sabah (North Luconia and Sabah Platform) show relatively high geothermal gradients overall, averaging 80 °C/km in North Luconia and 87 °C/km in the Sabah Platform. The higher heat flows in the deep-water areas are consistent with the region being underlain by extended continental terrane of the South China Sea margin. From the thermal conductivity models established in this study, the average heat flows are: Malay Basin (92 mW/m2), Sarawak Shelf (95 mW/m2) and Sabah Shelf (79 mW/m2). In addition, the average heat flows for the deep-water areas are as follows: Sabah deep-water fold-thrust belt (66 mW/m2), Sabah Trough (42 mW/m2), Sabah Platform (63 mW/m2) and North Luconia (60 mW/m2).

A technique for intra-procedural blood velocity quantitation using time-resolved 2D digital subtraction angiography

Background 2D digital subtraction angiography (DSA) is utilized qualitatively to assess blood velocity changes that occur during arterial interventions. Quantitative angiographic metrics, such as blood velocity, could be used to standardize endpoints during angiographic interventions. Purpose To assess the accuracy and precision of a quantitative 2D DSA (qDSA) technique and to determine its feasibility for in vivo measurements of blood velocity. Materials and methods A quantitative DSA technique was developed to calculate intra-procedural blood velocity. In vitro validation was performed by comparing velocities from the qDSA method and an ultrasonic flow probe in a bifurcation phantom. Parameters of interest included baseline flow rate, contrast injection rate, projection angle, and magnification. In vivo qDSA analysis was completed in five different branches of the abdominal aorta in two 50 kg swine and compared to 4D Flow MRI. Linear regression, Bland-Altman, Pearson’s correlation coefficient and chi squared tests were used to assess the accuracy and precision of the technique. Results In vitro validation showed strong correlation between qDSA and flow probe velocities over a range of contrast injection and baseline flow rates (slope = 1.012, 95% CI [0.989,1.035], Pearson’s r = 0.996, p < .0001). The application of projection angle and magnification corrections decreased variance to less than 5% the average baseline velocity (p = 0.999 and p = 0.956, respectively). In vivo validation showed strong correlation with a small bias between qDSA and 4D Flow MRI velocities for all five abdominopelvic arterial vessels of interest (slope = 1.01, Pearson’s r = 0.880, p = <.01, Bias = 0.117 cm/s). Conclusion The proposed method allows for accurate and precise calculation of blood velocities, in near real-time, from time resolved 2D DSAs.

A less invasive system for the direct measurement of ventilation in fish

Most previous systems for quantifying ventilatory flow in fish involve prior anesthesia and difficult surgery to sew or glue membranes to the animal, which are undoubtedly stressful. By modification of the original “van Dam box” design and incorporation of an electromagnetic blood flow probe, we have developed a less invasive system that avoids these problems and provides breath-to-breath measurements of ventilatory flow in real time. The fish can be quickly moved in and out of the apparatus, facilitating repeated measurements on the same animal after different treatments. We have used the system to document the hyperventilatory and hypoventilatory responses to environmental hypoxia and hyperoxia, respectively, in both ∼400-g trout (Oncorhynchus mykiss) and 10-g goldfish (Carassius auratus); the method is easily adaptable to fish of other sizes. Separate experiments on trout have demonstrated that responses to these treatments in buccal pressure amplitude, breathing frequency, and ventilation index are not altered by the attachments used in the apparatus. This less invasive methodology may prove more acceptable to animal ethics committees.

PSVIII-9 Effects of different sources and levels of dietary iron and selenium on the postprandial net portal appearance of these minerals in pigs

This study compares the post-absorptive levels of iron (Fe) and selenium (Se) in pigs fed different sources and levels of these minerals. Twelve 55-kg pigs were surgically equipped with portal and carotid catheters and a portal ultrasonic flow probe and used in a cross-over design to assess the 11-hours net portal-drained viscera (PDV) flux of serum Fe and Se after ingestion of boluses containing adequate (A; 200 and 0.6 mg) or high (H; 400 and 1.2 mg) levels of these minerals from dietary inorganic (I) or organic (O) sources. Arterial Fe concentrations increased (158 %) within the first six hours post-meal and gradually decreased thereafter (P &lt; 0.01). Values for I were greater than O until six hours post-meal (P &lt; 0.01) and for A than H between five and eight hours post-meal (P ≤ 0.01). There was a tendency for the interaction source x level (P = 0.07) on net PDV fluxes of Fe where values for AI were greater than AO (P = 0.02). The cumulative Fe PDV appearance (% of intake) was greater for I (2.2 %) than O (-1.7 %) after four hours post-meal (P = 0.02) but this effect was no longer detected at 11 hours post-meal. Arterial Se concentrations decreased by 7 % from pre-meal values until 11 hours post-meal (P &lt; 0.01) and this decline was more pronounced for O than I (P = 0.03). Net PDV flux of Se was positive but only during the first 90 minutes post-meal (P &lt; 0.01). The cumulative Se PDV appearance (% of intake) was greater for I (20.0 %) than O (-3.8 %) at 45 minutes post-meal (P = 0.04) but this effect did not persist thereafter. In conclusion, net availability of Fe and Se was greater for I than O during the early post-meal period. Whether these results reflect non-absorption or greater O intestinal retention remains to be elucidated.

Minor impact of constraint from perivascular flow probes on wave intensity analysis

Perivascular flow probes are considered the gold-standard for measuring volumetric blood flow in animal studies. Although flow probes are generally placed non-constrictively around the vessel of interest, pressure-elevating interventions performed during an experiment may lead to vessel expansion and some probe-vessel impingement, particularly in highly compliant vessels such as adult sheep aorta or major pulmonary arteries in fetus lambs. This study assessed to what extent such mild flow probe constraint may impact on wave intensity analysis. We also investigated whether errors arising from flow probe constraint could explain apparent pressure reflection indices ( Rp > 1) that have been observed in fetus lamb pulmonary arteries under some experimental conditions. These questions were investigated with one-dimensional models of an adult sheep aorta and fetus lamb pulmonary artery, with a virtual flow probe incorporated as a non-linear external constraint term in the vessel constitutive equation. Model-derived flow and pressure were subjected to standard analysis procedures that would be applied experimentally (correcting for apparent velocity lags and calculating wave speed via the PU-loop method). For the adult sheep model, simulations covering a wide range of haemodynamic conditions revealed a mostly minor effect (<10%) of probe constraint on the intensity and pressure effects of the three major waves (forward compression wave, forward decompression wave, backward compression wave). Moreover, flow probe constraint had essentially no impact on Rp in the fetus lamb model, suggesting that such constraint is unlikely to be responsible for an observed Rp > 1. Mild flow probe constraint is likely to have little impact on wave intensity analysis.

Robotic sheath-flow probe electrospray ionization/mass spectrometry (sfPESI/MS): development of a touch sensor for samples in a multiwell plastic plate

In the previous work, sheath-flow probe electrospray ionization (sfPESI) equipped with a touch sensor was developed for conducting samples.