ResNet and CWT Fusion: A New Paradigm for Optimized Heterogeneous Thin Reservoir Evaluation

The endeavor to explore and characterize oil and gas reservoirs presents significant challenges due to the inherent heterogeneities that are further compounded by the existence of thin sand layers encapsulated in shale strata. This complexity is intensified by limited and low-resolution seismic data, missing critical well-log information, and inaccessible angle stack data. Conventional reservoir classification approaches have struggled to address these issues, primarily due to their limitations in handling missing data effectively and, hence, precise estimations. This study focuses on the characterization of thin, heterogeneous potential sands of the B-interval within the Lower Goru Formation, a proven gas reservoir in the Badin area. The reservoir sands with varying thicknesses are assessed in detail for their optimized description and field productions by handling challenges, including low seismic resolutions, heterogeneities, and missing data sets. An innovative solution is developed based on the integration of continuous wavelet transform (CWT) and machine learning (ML) techniques for the approximation of missing data sets, i.e., S-wave (DTS), along with enhanced elastic and petrophysical properties. The improved properties are augmented by the high resolution attained by CWT and captured variability more profoundly through the implication of residual neural networks (ResNet). The limitations of conventional approaches are harnessed by ML solutions that operate with limited input data and deliver significantly improved results in characterizing enigmatic thin sand reservoirs. The high-frequency petroelastic properties reliably determined the thin heterogeneous potential sand bodies and illuminated a channelized play fairway that can be tested for additional wells with low-risk involvement.

Petrography and Geochemistry of Dolomites of Samanasuk Formation, Dara Adam Khel Section, Kohat Ranges, Pakistan

Replacement dolomite occurs in Jurassic Samanasuk Formation in Dara Adam khel area of Kohat ranges, North-Western Himalayas, Pakistan. This study, for the first time, document the process of dolomitization and evolution of strata bound dolomitic bodies. Field investigation, petrography and geochemistry helped in unraveling the formation of several dolomitic bodies. Petrographically dolomites comprises of: (1) medium grain crystalline planer subhedral dolomite (Dol-I); (2) fine grained crystalline anhedral non-planer dolomite rhombs (Dol-II); (3) medium to coarse grained crystalline subhedral-anhedral non-planer dolomite (Dol-III) and coarse to very coarse grained crystalline saddle dolomite cements (SD). The saddle dolomites (SD) postdate the replacement dolomites and precede telogenetic calcite (TC) cements. Stable O and C isotope analysis shows that these dolomites have δ18Ovpdb ranging from -4.09% to -10.4 whereas the δ13Cvpdb ranges from +0.8 to +2.51. Major and trace elements data show that Sr concentrations of 145.5 to 173 ppm; Fe contents of 2198 to 8215 ppm; and Mn contents of 93.5 to 411 ppm. Petrographically replacive dolomites, saddle dolomite, and δ18Ovpdb values depicts neomorphism of replacement dolomites that were formed earlier were exposed to late dolomitizing fluids. As a result of basin uplift during the Himalayan orogeny in Eocene time, dolomitization event was stopped through occurrence of meteoric water. The Main Boundary Thrust (MBT) and its splays were most likely essential conduits that channelized dolomitizing fluids from siliciclastic rocks that were buried deeply into the Jurassic carbonates rocks, leading to more extreme dolomitization.

Complications related to intra-aortic balloon pump in cardiac surgery: a decade later

BACKGROUND

Our centre in 1995 reported 26% of vascular complications in cardiac surgical patients treated with intra-aortic balloon pump (IABP). However, during the last decade there have been improvements in IABP technology and insertion techniques. We aimed to evaluate the impact of these changes on the incidence of IABP-related complications in cardiac surgery.

METHODS

Demographics, indications, technique and complication rate in 186 consecutive patients treated with IABP from January 1994 to December 1998 (Group I) were compared with 323 consecutive patients treated with IABP from January 1999 to December 2003 (Group II) at our regional cardiothoracic centre. Data was variably expressed as mean with or without range and either standard deviation or range. Statistical significance was accepted at P<0.05.

RESULTS

There were 121 (65%) and 194 (60%) males in Group I and II, respectively. The mean age was 66+/-12.1 (17-88) years and the mean duration of IAPB use was 43.5h (range 3-144 h). Overall complication rate was 10% in Group I and 2% in Group II whereas vascular complications accounted for 3% in Group-I and 1% in Group-II. Logistic regression analysis demonstrated cardiogenic shock being strongly correlated to in-hospital mortality (OR 4.68; P=0.004) followed by older age (OR 3.12; P=0.034) and ejection fraction <35% (OR 1.78; P=0.03).

CONCLUSION

The study demonstrated a significant decrease in the IABP-related complications even though complexity of cases referred for surgery has increased. Henceforth, the risk of 1% vascular complications should play little influence on decision-making regarding the use of IABP.

Evolution of vascular brachytherapy over time: Data from the RENO-registry analysis

OBJECTIVE

To study the evolution of procedural variations in vascular brachytherapy (VBT) and their relationship to medium-term outcome.

METHODS AND RESULTS

The RENO (European Surveillance Registry with Novoste Beta-Cath) prospectively collected procedural and clinical outcome data on 1098 patients treated with VBT. Patients were divided for this analysis into Group-I, the first 50% registered, and Group-II, the last 50% registered. Shorter 30-mm source trains were more commonly used in Group-I (p<0.001) while longer 40-mm (p=NS) and 60-mm (p<0.001) source trains were more commonly used in Group-II. Mean dwell time for radiation seeds was longer in Group-II compared to Group-I (4.20+/-1.48 min vs. 4.14+/-1.44 min; p<0.05). Mean radiation dose was higher in Group-II (19.73+/-3.33 Gy vs. 17.92+/-2.68 Gy; p<0.001). Cutting balloons were more frequently used in Group-II (p<0.001). There was significant drop in the incidence of geographic miss in Group-II (3.2% vs. 9%; p<0.00005). There were nonsignificant trends towards reduction in angiographic restenosis, target vessel (TV) revascularisation, death and major adverse cardiac events (MACE).

CONCLUSION

There has been a learning curve and evolution of VBT techniques over time. In general, there has been an increase in radiation source length, use of cutting balloons, dwell time and radiation dose. This has resulted in significant reduction of geographic miss and a trend towards improve clinical outcomes. Continued development may result in further improvement in the treatment of patients with in-stent restenosis (ISR).

Failure of intravascular ultrasound to identify the site of recurrent focal coronary spasm during stenting

Focal coronary spasm is often associated with an area of mural plaque disease. This report describes a patient with recurrent severe coronary spasm unresponsive to medical treatment. Coronary arteriography and intravascular ultrasound identified a candidate area of minor coronary atheromatous disease but ergonovine provocation testing showed the spastic coronary segment to be distal to and distinct from this area. Coronary stenting of the site identified by ergonovine provocation testing was effective in relieving provoked and spontaneous spasm.

Ventricular fibrillation during electrical cardioversion of pre-excited atrial fibrillation

The Wolff-Parkinson-White syndrome can rarely present with pre-excited atrial fibrillation. In this condition the short refractory period of the accessory pathway can lead to rapid atrioventricular conduction. There is then a danger that at high heart rates the irregular broad complex tachycardia that results can deteriorate into ventricular fibrillation. The initial management of patients presenting in pre-excited atrial fibrillation requires cardioversion to sinus rhythm. This can be performed by DC cardioversion or pharmacological means. This paper describes the case of a patient presenting in pre-excited atrial fibrillation where electrical DC cardioversion lead to transient iatrogenic ventricular fibrillation.

Identifying priority patients for coronary angiography

We conducted an open observational study with blinded endpoint evaluation to validate the use of the Duke treadmill score in identifying patients likely to require coronary intervention. We studied 101 consecutive patients referred for coronary angiography from a cardiology clinic. All patients had a Bruce protocol exercise test. A 70% stenosis was regarded as significant. Patients were referred for percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) surgery, if indicated. The Duke score was calculated as follows: exercise time (min) - (5 x ST segment deviation [mm]) - (4 x angina index [text]). Patients were classified into low, medium and high risk. The patients at high risk are more likely to have a significant stenosis (53/58 vs 30/43: p = 0.01 [OR 4.59 95% CI 1.34-16.6]) and require CABG or PTCA (47/58 vs 16/43: p < 0.001 [OR 7.21 95% CI 2.69-19.8]) than those at medium/low risk. Multiple logistic regression analysis, including ST segment depression, exercise time and symptoms shows that the score independently predicts a significant stenosis (p = 0.002) and the need for coronary intervention (p = 0.001). Introducing the score can help to identify those patients who need priority investigation.

An epidemiological study of falls on integrated general medical wards

Reducing falls in hospital requires an environmental as well as a patient-orientated approach. We studied patient and ward characteristics relating to falls in an acute setting. In a prospective open observational study, we examined fall characteristics in two nuclear designed wards (A and B) and a longitudinal ward (C). We recorded 63 falls among 1609 patients. Ward C had the most falls (31 vs 18/14; p = 0.01), fall positive days (29 vs 15/10; p = 0.002) and fallers (27 vs 13/12; p = 0.001; OR 2.54, CI--1.41-4.57). Ward C had a higher cumulative risk of falls (p = 0.006) and fall positive days (p = 0.003). Choice of ward was a significant independent risk factor for falls (p = 0.01) when controlled for age, sex, and diagnostic variation between the wards. Most falls were intrinsic (A 66.7%, B 64.2%, C 61.3%, p = 0.45). A significantly higher proportion of falls on ward C occurred by the bed (p = 0.04). Significant differences exist between the wards, and fall reduction programmes should identify and compensate for adverse ward-related factors to increase the effectiveness of patient-targeted fall risk assessments.