TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractProduction from the deepwater Bonga turbidite reservoirs was started in November 2005. As with all waterflood and Enhanced Oil Recovery schemes, 'world-class' Well and Reservoir Management (WRM) is the foundation of a successful project. A comprehensive WRM plan was defined for Bonga very early in the project, and its implementation from start-up has demonstrated tremendous value.More than 220 MMstb have been produced as of March 2009 from 13 subsea producers, and reservoir pressures have been maintained by water injection from the start of production in 13 subsea high rate water injectors, allowing high field production rates to be sustained. Well and reservoir performance data obtained during the first three years of production, and information from 4 D seismic shot in early 2008 are now used to optimize the planning and drilling of additional wells as part of the Phase 2 development drilling project. Bonga is a 'brownfield' that is not immune to normal well and asset integrity issues, and declines in well injectivity and productivity. Ability to respond swiftly to these issues is part of the Bonga WRM Plan. This paper presents key elements of successful WRM in Bonga. These include people factor and cross discipline integration, Smart Fields ® capability, 'live' WRM Plan and monitoring, good understanding of subsurface, application of integrated production modelling, intervention readiness and effective well integrity management. The paper concludes on key learnings applicable to future deepwater waterflood projects.

This study was composed of two experiments which investigated the response of two strains (Arbor Acre and Cobb 500, respectively) of broiler chickens to in ovo injection of inorganic salts of zinc, copper and their combination. A total of 300 hatching eggs [only 148 (59.20 %) and 232 (90.27 %), respectively, were fertile] each of Arbor Acre and Cobb 500 strains of broiler chickens were used in both experiments. These eggs were distributed into four treatments: control, in ovo inorganic Zn (80 µg.egg−1), Cu (16 µg.egg−1) and combined Zn and Cu (80 µg.egg−1 Zn and 16 µg.egg−1 Cu). The data obtained in both experiments were subjected to Completely Randomized Design (CRD) at the 5 % probability level. The results showed increased hatchability (P < 0.05) in eggs injected with the combination of inorganic salts of Zn and Cu in Experiment I and daily intake was influenced in both experiments. The carcass traits, organ development and gut morphometry were not significantly influenced by the treatment groups. The total serum protein and albumin of the birds were significantly (P < 0.05) increased by in ovo injection of inorganic salts of Zn and Cu at day 49 in the Experiment I. The study concluded that in ovo injection of inorganic salts of Zn at 80 µg.egg−1 and/or Cu at 16 µg. egg−1 could be adopted to increase feed intake with: attendant enhanced growth, enhanced immune response, increased albumin and total protein contents of blood serum in the strains of broiler chickens used.

Bonga producer (Well-X) became severely impaired during a series of interventions (to address SCSSV failure), with oil potential dropping from 18 to 3 kbod. The Well and Reservoir Management team believed the initial impairment was most likely caused by fines migration and secondly by fluid (MEG and brine) losses to the formation during interventions. A two-fold treatment was recommended –solvent (surfactant) and half stre gth mud acid to target the two impairment mechanisms. Considering the relatively low productivity and remaining reserves, the downside risk was low from a subsurface perspective. The major concerns were related to HSSE and integrity risks pertaining to unspent FPSO. Lessons learnt similar jobs by other acid flow-back to the Bonga from successful executions of Operators enabled the Bonga team to demonstrate the necessary risk management and purs e the concept towards execution. To minimize cost, the recommended deployment method was by bull-heading the treatment from the Field Support Vessel, via a flexible hose connected to the tree, and subsequently to back produce the well fluids to the FPSO with injection of Soda Ash to neutralize any unspent acid on the topsides. The key challenges that needed to be addressed were: Identifying an appropriate stimulation recipe, Ensuring adequate pump rate of stimulation fluid given limited pressure rating of the flexible hose, Managing flowback of unspent acid to topsides, Metallurgy compatibility with the stimulation fluid, ydrate risk and Production of H2S from chemical reaction. Full integration of the various functional aspects was essential for effective planning and execution. The Well-X stimulation led to an increase in production frrom 3 to 22 kkbod, with PI improving from 1.4 to 86 bpd/psi; a PIF of 60. Industry experience shows that gaains from mud acid stimulation to attack fines can typically be sustained for up to 12 months, while the partial gain from surfactant to remove MEG/brine impairment is expected to be sustained permanently. TThhis success paves the way for further acid stimulation in the Bonga field where fines migration is typical among producers, and provides opportunities for production acceleration in the field and other upcoming developments.

One hundred and forty-four, one day – old broiler (arbor acre strain) chicks were used in a 49-day trial to assess the influence of oral administration of black seed oil on growth performance, carcass traits and bacteria load in broiler chickens. The birds were divided into four groups (36 per group) and randomly assigned to treatments with varying levels of black seed oil (1.5 ml/L, 3.0 ml/L and 4.5 ml/L of water) and control (antibiotics). Data obtained were subjected to one-way Analysis of variance at α0.05 . Oral administration of varying levels of Nigella sativa oil did not have any significant (P>0.05) effect on the growth performance indices (final weight includes 1899.49, 1940.28, 1888.51 and 1795.83g across the groups) and carcass traits of broiler chickens. Black seed oil had no significant (p>0.05) effect on the faecal bacteria count, only numerically reduced total blood coliform count with increasing 6 dosage of Nigella sativa oil (0.50, 0.40, 0.33 and 0.40 × 10 cfu/ml) in water while caecal coliform reduced (p <0.05) markedly at 4.5ml/L dosage (2.03 vs 2.53, 2.37, 2.43). It was concluded that a minimum dosage of 4.5ml/L of black seed oil be adopted for a significant reduction in bacterial load in chickens.

The Bonga field came on stream in November 2005 with 16 predrilled wells (9 producers and 7 water injectors). The field is characterised by unconsolidated rock but with permeabilities in the multi darcy range. The reservoirs are undersaturated and contain light crudes in the 28-35 deg API range. The field contains STOIIP of over 4 billion barrels across 6 reservoirs and it is developed by waterflood. The reservoir characteristics have culminated in high injection and production rates per well with injection rates above 60 kbpd and production rates above 50 kbpd achieved for some wells. Plateau field production and injection was achieved soon after start up with production and injection at or near nameplate capacities of 225 kbopd and 300kbwpd respectively. This continued until H1 2008 when injectivity decline set in. As water breakthrough had already occurred, the reduced deliverability of the water injectors further compromised the voidage replacement capacity of the system. Net result was that the field fell off plateau but production was soon restored to near plateau level. Since then, production has been off plateau intermittently with the integrated team taking action to ameliorate the situation and to bring the field back to near plateau level of some 200 kbopd. The key issues/challenges that have resulted in production decline include: injector impairment, inadequate topsides injection capacity, injection well failures, baffles mitigating injector-producer connectivity, producer impairment, ScSSV failures, injector longevity, injection water quality, produced water handling, premature water breakthrough. Cross discipline corrective and innovative measures have been taken to address the above challenges and maximise value from this field. The measures cut across subsurface, wells, topsides, subsea and production operations disciplines and include: Backflush/refrac, acid stimulation, increased injection capacity, improved injection water quality, fracture mode injection only, drilling of horizontal wells as preferred option for injectors, breaking down of connectivity baffles by sustained high rate water injection etc. This paper captures the key learnings from the Bonga experience and the corrective measures applied. The field overview and performance history of the field are illustrated in figs 1&2.