Summary Calcium carbonate (CaCO3) scale is a common problem in the oil industry, leading to reduced well performance and obstruction of the safety valves. Recent field experiences indicate that scaling may be a problem at lowersaturation ratio (SR) than earlier anticipated. In a high-pressure, high-temperature scale cell, crystal growth in synthetic formation water has been studied. Induction times and growth rates have been determined by use of a microscope cell. The results have been interpreted by use of nucleation theory. The findings indicate that wells may be safely operated at SR below 2.5 at85°C. At higher temperature, crystal growth is less dependent on SR and the temperature dominates the system. Care should therefore be taken when operating wells at temperatures greater than 100°C. Introduction Precipitation and deposition of CaCO3 is a common problem in the oil industry. The scaling problems occur during pressure decrease of the produced formation water. The consequence may be reduced performance of the well and in some cases influence on the operation of downhole safety valves(DHSVs).The carbonates precipitate from the produced water as release ofCO2 gas gives increased pH and supersaturation of CaCO3 . The kinetics of the reaction is a function of temperature (i.e., slow kinetics at low temperature). The rule of thumb for prediction of CaCO3 scaling problems has until lately been based upon the work by Oddo and Tomson. Their conclusion from field experiences in the Hitchcock field in Texas, and Farida offshore Indonesia, was that produced water from vertical wells may be supersaturated up to saturation ratio SR=2.51 before any scaling problems occur. The bottomhole temperature was moderate (88 to 104 °C). In some relatively recent field developments, the design of the completion and the need for chemical placement in new wells(e.g., scale inhibitor injection lines) have been partly based on these findings.

The sub sea development of the Ormen Lange gas field located in the Norwegian Sea will use MEG (mono-ethylene-glycol) for hydrate inhibition. Gas, condensate and MEG + water will be transported through a multiphase carbon steel pipeline to the onshore process plant at Nyhamna located on the west coast of Norway. pH adjustment and film forming corrosion inhibitor will be used to control the corrosion rate in the pipeline. Although the corrosion rate is low during production, iron will be produced due to corrosion and follow the MEG/water phase. Most of the iron will be removed as iron carbonate particles during the MEG regeneration process but about 10ppm iron as particles and ions is expected to circulate in the MEG-loop. Production of formation water will result in carbonate scaling when pH stabilised MEG is used as corrosion control unless a scale inhibitor is used. Three commercial scale inhibitors have been tested for this system. Tests have been performed without iron, with iron ions and with iron carbonate particles present. The results from the tests showed that the scale inhibitor concentration had to be increased considerably when iron ions were present compared to experiments without iron. The scale inhibitors performed poorer at the same inhibitor concentration in tests where iron carbonate particles were present than in tests with iron ions. Scale inhibitor concentrations up to 400ppm were used in the tests without achieving satisfactory scale protection when iron particles were present. In addition tests with lowering the amount of pH stabiliser have been performed. Tests with combining scale and corrosion inhibitors have also been performed. No scale inhibitors have shown satisfactory performance when iron carbonate particles were present in the tests. Introduction The Ormen Lange gas field is a sub sea development located in the Norwegian Sea 120 km from the shore in mid Norway. Norsk Hydro Produksjon is operator for the planning and development phase. Shell will take over as operator when Ormen Lange comes on-stream in October 2007. Sub-zero seabed temperatures in combination with the high-pressure conditions in the carbon steel multi phase pipelines favour the formation of gas hydrates and ice. MEG (mono-ethylene-glycol) will be injected to prevent hydrates and ice from forming in the sub sea pipeline. The MEG will be pumped out to the injection point in carbon steel pipelines. From the start of production the wells will also produce condensed water (CW), CO2 and organic acids, besides hydrocarbons. The pH of this water phase will be low due to the presence of CO2 and organic acids. pH adjustment and film forming corrosion inhibitor (CI) will be used to control the corrosion rate in the carbon steel pipeline1. The pH stabiliser will be added to the MEG. The degree of pH adjustment varies from full pH stabilisation to partial pH stabilisation. When partial pH stabilisation is used, a film forming corrosion inhibitor has to be used in combination with pH stabilisation to achieve corrosion control in the pipeline. Although the corrosion rate is low during production, iron will be produced due to corrosion and follow the MEG/water phase. Most of the iron will be removed as iron carbonate particles during the MEG regeneration process but about 10ppm iron as particles and ions is expected to circulate in the MEG-loop. Later in the field life formation water (FW) breakthrough may occur in the wells resulting in a co-production of FW and CW. CaCO3 crystals may form if the formation water mixes with the pH-stabilised MEG. The high pH and the presence of MEG reduce the solubility of CaCO32. The crystals may form a layer on the pipeline wall. The MEG that is pumped out from the onshore facilities is denoted Lean MEG, while Rich MEG is the Lean MEG after this has been mixed with the well fluids. Several commercial scale inhibitors (SI) have been tested in dynamic tube blocking tests and static tests. Since iron is known to have influence on the performance of scale inhibitors3 their efficiency was determined with and without the presence of iron.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractCalcium carbonate scale is a common problem in the oil industry leading to reduced well performance and obstruction of the safety valves. Recent field experiences indicate that scaling may be a problem at lower Saturation Ratio (SR) than earlier anticipated. In a high pressure, high temperature Scale Cell crystal growth in synthetic formation water has been studied. Induction times and growth rates have been determined using a microscope cell. The results have been interpreted using nucleation theory. The findings indicate that wells may be safely operated at SR below 2.5 at 85 o C. At higher temperature crystal growth is less dependant on SR and the temperature dominates the system. Care should therefore be taken when operating wells at temperature above 100 o C.

Spinal fluid samples were obtained from 18 asphyxiated term (GA 40 + 2 wks, BW 3064 2 583 gms) neonates to determine whether CSF LDH and CPK are useful predictors of neurologic disability following perinatal asphyxia. These values were compared with CSF enzymes from 7 term (GA 40 5 1 wk, BW 3521 + 510 gms) nonasphyxiated infants. Asphyxia was present if the 5 min. Apgar score was < 4 or pH < 7.0 or failure to breathe by 10 min. or hypotonia persisting for 2 hrs. Spinal fluid samples were obtained from the asphyxiated infants at 11.8 2 5.3 hrs. and from control infants at 32.4 + 29 hrs. Neurodevelopmental follow-up ranges from 3-15 months in the 15 surviving infants. Abnormal outcome includes death (3), some form of cerebral palsy (8), a& normal Gesell screening (7) or abnormal brain stem auditory responses (4). 8 infants are presently normal. CSF-LDH ( Si dbury) .A number o f endogenous chemical f a c t o r s p l a y a r o l e i n development o f the b r a i n . W e have shown t h a t several peptide neurotransmitters i n f l u e n c e neural development by permanently r e g u l a t i n g t h e expression o f t h e i r own receptors. The regulat i o n o f t h e r e c e p t o r s a f f e c t s t h e animalbs s e n s i t i v i t y t o t h e peptide and i t s behavior. For example, substance P (SP) i s a p e p t i d e important i n p a i n pathways. When administered t o neon a t a l r a t s (1 ~g/pup/day) d u r i n g t h e f i r s t week a f t e r b i r t h , SP permanently increased t h e number o f SP r e c e p t o r s i n several sensory regions o f the b r a i n . The r a t s as a d u l t s showed g r e a t e r s e n s i t i v i t y t o cutaneous s t i m u l a t i o n than c o n t r o l r a t s . S i m i l a rl y , r a t s i n j e c t e d as neonates w i t h o p i a t e peptides d u r i n g t h e f i r s t week a f t e r b i r t h ( 1 pg/pup/day) had more o p i a t e recept o r s i n several b r a i n regions than c o n t r o l s . These r a t s showed g r e a t e r t o l e r a n c e o f m i l d l y noxious s t i m u l a t i o n than c o n t r o l s , i n d i c a t i n g t h a t they were more s e n s i t i v e t o t h e i r endogenouslyreleased o p i o i d peptides.These experiments i n d i c a t e t h a t e a r l y exposure t o neuropeptides has a long-term i n f l u e n c e on b r a i n f u n c t i o n by r e g u l a t i n g expression o f peptide receptors, and t h e r e f o r e t h e b r a i n ' s a b i l i t y t o respond t o neuropeptides.NEUROTOXIC COMPLICATIONS OF CONTRAST CT I N CHILDREN. Computed c r a n i a l tomography (CT) has been considered a safe and accurate method f o r studying i n t r a c r a n i a l l e s i o n s i n children. As a d i a g n o s t i c adjunct, r a d i o g r a p h i c c o n t r a s t m a t e r i a l i s adm i n i s t e r e d i n t r a v e n o u s l y ( I V ) t o enhance and f u r t h e r c h a r a c t e r i z e l e s i o n s such as vascular malformations. T r a d i t i o n a l i o n i c cont r a s t agents can penetrate t h e blood b r a i n b a r r i e r (BBB) and e x e...