Techniques of Reinjecting 100 of Produced Water in Daqing Oil Field

摘要

In the history of over 40 years of development, DaqingrnOilfield has witnessed three phases of development: basic wellrnpattern, infill well pattern, and tertiary oil recovery. To copernwith that, three sets of systems including general producedrnwater re-injection, produced water fine treatment re-injection,rnand polymer flooding produced water re-injection have beenrnset up catering to the varied requirements in injection waterrnquality of different well patterns. Among them, general waterrnre-injection system feeds the basic well pattern and primaryrninfill well pattern; fine treatment water re-injection systemrnserves secondary and tertiary infill well pattern as well asrnmarginal low-permeability oilfields; and polymer water reinjectionrnsystem is dedicated mainly to polymer floodingrnblocks.rnAiming to satisfy the requirements of the oily producedrnwater treatment and oilfield water re-injection development,rnand based on the specifications of the original produced liquidrnand output water, Daqing Oilfield water treatment system isrndivided into four subsystems, they are: general produced waterrntreatment, produced water fine treatment, polymer floodingrnproduced water treatment, and clear fresh water treatment.rnOriginal liquid to the produced water treatment subsystemrncomes from water flooding and dehydration stations, part ofrnthe treated water is re-injected to the basic well pattern and thernprimary infill well pattern, the remaining portion goes throughrnfine treatment before being re-injected into the secondary andrnthe tertiary infill well patterns. Original produced liquid to thernpolymer flooding produced water treatment subsystemrnoriginates from polymer flooding and dehydration stations,rnand all of which is re-injected to the basic well pattern and thernprimary infill well patterns after being treated. As for thernmarginal low permeability oilfields, due to their lowrnpermeability, the original liquid coming from dehydrationrnstations is treated straight in the fine treatment station beforernbeing totally re-injected, in locations where the producedrnwater quantity can not satisfy the injection demand,underground water and surface water will be treated to reachrnquality required by the low permeability reservoir injectionrnprocess.rnThe key process of the water re-injection technology is torntreat the produced liquid into standards required by reinjection.rnThis thesis is to introduce the produced waterrntreatment technologies used in Daqing.