Romanian oil production is characterized by mature fields with a big variety of different fluid parameters. The total number of wells exceeds 10,000, most of them equipped with sucker rod pumps. Corrosion has been a big challenge in the past decades. Metal consumption was a permanent problem causing high failure rates in pumping units, flowlines, pipelines and production facilities and thus leading to high well intervention and maintenance expenditures as well as to production losses. To maintain the oil production in this environment, the first steps concentrated on identifying corrosion mitigation measures leading to a distinct decrease of internal corrosion covering all operational units. Downhole inhibitor treatment was identified to be most effective to achieve this goal. A key issue was to find inhibitors in laboratory tests showing a maximum protection rate in many different production fluids thus minimizing the number of total inhibitors used. Subsequently the inhibitor treatment had to be established in the fields in a large scale and a corrosion monitoring system had to be established to verify the efficiency of the selected inhibitors in the field. This was done mainly by coupon measurement. The first results showed that inhibitor injection can achieve a high protection rate, but many measures have to be set to achieve an optimum inhibitor concentration at each location. This paper gives an overview of the first results of an inhibitor treatment and corrosion monitoring program recently established and of future corrosion monitoring activities in Romania?s mature oil fields.
Fluid properties (e.g. temperature; pressure; composition of oil, gas and water; water cut; existence of scales, wax, sand; flow velocities)
Material (e.g. equipment size; year of construction; material; wall thickness; corrosion allowance; design temperature and pressure; max. operating temperature and pressure)
Protection (e.g. type, amount of corrosion inhibitor; type of treatment; scale inhibitor; paraffin inhibitor; bactericides; demulsifiers; coating; sacrificial anodes; cathodic protection, chemical injection points; corrosion rates)
Inspection (e.g. NDT; UT; repair; replacement; lifetime; time between failures; leaks)
Operators of mature oil fields commonly are confronted with a variety of problems. This is particularly the case when ownership of the field has changed and some of the original conditions are unknown. In many cases the maintenance of the facilities and installations had been neglected in the past. The first step after the acquisition of such a mature oil field should be proper compilation of all relevant data for corrosion management including following parameters:This data compilation should be the basis for a risk assessment to define the main problem areas which is the prerequisite for further corrosion control measures.
Romania has a long tradition in producing oil and gas, the first oil production goes back 150 years. Romanian onshore oil production is characterized by mature field environments and marginal production. More than 10,000 wells are producing approximately 200,000 BOEPD. In 2004 the Romanian oil company Petrom was privatised and OMV acquired a majority stake and started the initiative for improving the corrosion situation.