Enhancing volume and salinity of production water in oil and gas wells, Case study: Mozduran gas reservoir

The production of oil and gas in oil and gas fields is accompanied by production of water (Produced Water). Most of the reservoirs at the beginning of production have fresh water; but with passing time due to the increase in productions and decrease in pressure of reservoir, the produced water gradually becomes saline. The saline Production water causes severe corrosion in pipelines and well head facilitis leading to reduction in gas production. Determining the origin of salinity for reducing the salinity is most important. Khangiran gas field is located in the northeast of Iran which composed of two separate gas formations, Mozduran at lower and Shurijeh at the upper part. The produced water samples were collected from fresh and salty wells in the Mozduran reservoir as well as two deep samples from brine below the gas reservoir (at depth of 3 km) for comparison and different analyzes. The Mozduran reservoir has two major problems, high salinity of the produced water, as well as the volume of water produced, rendering some wells unexploitable. The results revealed that two deep water samples have different behaviors. The deep sample No. 17, taken at a higher elevation than sample No. 13, showed the signs of salt dissolution; whereas the brine from sample no.13 had the origin of the evaporated old sea water. Therefore, any of these brines in the Khangiran reservoir can be the possible source of salinity in produced waters. The saline produced water samples showed a similar behavior to brine sample no.13. The source of fresh produced water is also the condensation of water vapor in the reservoir during production.