This paper describes the interventionless approach that was successfully executed during the Pyrenees early production phase to identify the timing and location of water breakthrough. Chemical inflow tracers were installed in key production wells within the lower completion along the horizontal production sections. Results from this work have supported the reservoir simulation history matching process and confirmed the performance of the inflow control devices (ICDs). These data in conjunction with the real time rate information from subsea multiphase meters has allowed proactive reservoir and production management that has contributed to the early identification of additional infill opportunities.

The oil and gas fields of the Exmouth Sub-basin, offshore WA, have presented a number of significant challenges to their exploitation since the first discoveries of heavy oil and lean gas were made in the late 1980s and early 1990s. Presently, some 20 oil and gas fields have been discovered in a variety of Late Jurassic to Cretaceous clastic reservoirs from slope turbidites to deltaic sands. Discovered oils are typically heavily biodegraded with densities ranging from 14–23° API and moderate viscosity. Seismic imaging is challenging across some areas due to pervasive multiples and gas escape features, while in other areas resolution is excellent. Most reservoirs are poorly cemented to unconsolidated and thus require sand control. Modest oil columns, most with gas caps, and variable permeability, present challenges for both maximising oil recovery and minimising the influx of water and gas. Oil-water emulsions also present difficulties for both maximising oil rate and metering production. To date, more than 300 MMbbls have been produced from five developments (Enfield, Stybarrow, Vincent, Van Gogh and Pyrenees), and in 2013 the Macedon gasfield began production. This peer-reviewed paper focuses on the variety of technologies—geoscience, reservoir, drilling and production—that have underpinned the development of these challenging fields and in doing so, transformed the Exmouth into Australia’s premier oil producing basin.

The formation of oil-water emulsions presents a major challenge for the petroleum industry. Emulsions in wells and flowlines cause higher viscosities and lead to larger pressure drops, reducing production performance. The empirical modelling of emulsion viscosity as a function of water cut is presented. Measurement techniques for emulsion viscosity in a laboratory are explored and their use in a multiphase flow simulator to predict well and flowline pressure drops is explained. The reverse of this methodology can also be used with field data to back calculate the ostensible emulsion viscosity curve. Using the BHP Billiton operated Pyrenees oil development as a case study, this paper contrasts the laboratory derived and reverse engineered viscosity curves generated across a number of wells that have produced to the point of natural emulsion inversion. A possible mechanism for the differences between the two is proposed. In the latter part of 2014, a campaign of downhole demulsifier dosing across the Pyrenees fields was intiated with considerable success. The impact of this chemical injection on emulsion viscosity modelling is also explored in detail.

The Woollybutt Oil Field was discovered in 1997 and further appraisal drilling delineated two separate oil accumulations in the Early Cretaceous Barrow Group Sandstone; the Woollybutt North and South Fields. The Woollybutt North Field came on production in April 2003 with an expected field life of three years. Subsequent review and development drilling in 2005 extended the Woollybutt North Field life to 2008. The tie back of the Woollybutt South Field in 2008, previously thought to be an uneconomic area, has again increased total field life expectancy and consequently increased the expected ultimate recovery for the field. Issues with the unknown level of productivity of the poorer quality basal Mardie Greensand reservoir and the seismic velocity gradients across the field, generated a large uncertainty in both well productivity and structural closure of the field. A review was undertaken which integrated geophysical, geological and reservoir engineering expertise. This review resulted in the revision of the Woollybutt geological model and the development of the Woollybutt South Field. An additional benefit was to also extend the production life of the Woollybutt North Field. This paper describes the original geophysical and geological model and demonstrates how simulation history match feedback can influence the mapping of the structural closure of the field. This result was integrated with a wireline mini drill-stem test within the poorer quality reservoir sandstone and led to the development of a new geological model. Subsequently the decision was made to develop the Woollybutt South Field, which is dominated by this poorer reservoir; the basal Mardie Greensand. Woollybutt is operated by Eni Australia (65%) with partners Exxon Mobil (20%) and Tap Oil (15%).

Background: Road traffic accidents remains as one of the leading causes of death and life-long disability worldwide. Objectives: This study aimed to determine the prevalence and associated risk factors for road traffic accidents in Juba, South Sudan. Methods and materials: This are a retrospective study using data from registers at Juba Teaching Hospital and Directorate of Traffic police between 1st January to 31st December 2018. Data were collected, cleaned and entered into a computer database. Statistical analysis was performed using SPSS Version 21 Software. A variable with a p value of <0.05 was considered statistically significant. Results: Out of 7862 patients were recorded in the OPD at Juba Teaching Hospital (JTH), 7.3 % (575/7862) were road traffic accident (RTA) cases. This is at rate of 7313 per 100,000 of the population. Of all the 575 cases of RTA in JTH, 82% (472/575) were males and 18% (103/575) females with age ranging from 9 months to 97yrs and a mean age of 26.9yrs, SD+/-12.53. Most of the patients 37 % (214/575) were of age group 31-40years, with majority 36% (207/575) coming from an unidentified location. Munuki block had the highest 25.2% (145/575) within Juba city council , while areas outside Juba city council had the least 7.5% (43/575). Interestingly most of the patients 44 % (253/575) presented to the OPD at night, while 19 % (111/575) presented in the morning. Most 20 % (113/575) presented to the OPD in May 4 % (23/575). There were no cases in June.Out of 1081 drivers involved in RTA, age group 31-40yrs (37%), 21-30yrs (37%), 21-30yrs (36%), 31-40yrs (42%) and 31-40yrs (31%) had an outcome of car accidents causing death, severe injuries, slight injuries, damage and influenced by alcohol respectively with p=0.015. It was noted that 81% (926/1141) drivers had driving licenses, while 19% (215/1141) driving without licenses. Private cars were associated with the highest outcome;56% causing death, 50% causing slight injuries and 42% causing severe injuries with p=0.01. Unfortunately, 82% of drivers driving under alcohol influence were drivers driving private cars as the highest with p=0.000. Out of the 1472 cars registered, majority were private cars 38% (27/71), 36% (134/373), 47% (222/475) and100% (11/11) were involved in accidents causing death, severe injuries, damage to property and driven under influence of alcohol respectively with p=0.003. Motorcycles reminded leading cause of slight injuries, 39 % (214/542) but also the second leading in causing severe injury 35 % (190/542) as well as damage to property 20 % (96/475). Most of the cars 22% (13/58) caused accidents resulting to death as well as slight injuries 16.8% (67/404) in March; severe injuries 13.3% (39/291) seen in November, where as damage to the property 13.6% (40/296) in February. Accidents due alcohol intoxication 50% (16/32) were seen in January but p=0.58. Conclusion: Road traffic accidents still remain a public health problem in Juba with younger age drivers involved in accidents.