Short process integrated pre-separation water +
filtration produced liquid treatment reinjection technology

Technical background

1) Most of China's oil fields have entered the high water cut development period, the comprehensive water cut of crude oil is as high as 90%, and the liquid content and comprehensive water cut show an increasing trend year by year. A small increase in water content can lead to a large increase in liquid volume. Taking Shengli Oilfield as an example, the comprehensive water cut increased by 1%, and the liquid volume increased by about 40 million tons, an increase of 12.88%.

2) A large amount of produced water is transported to the combined station for centralized treatment, and the qualified produced water is returned to the water injection station for re-injection over a long distance.

Short process integrated pre-separation and filtration technology

Problems to be solved in high water cut oilfield

· Overload operation of gathering, transportation and output liquid treatment system.

· Ineffective heating of large quantities of produced water and long-distance round-trip transportation increase energy consumption and operating costs, operation management and maintenance costs; At present, the average round-trip gathering and transportation cost of Sinopec is 4.86 yuan /m3. If it is calculated according to 100×104 m3/d produced water, it needs to spend 4.86 million yuan per day, and the annual cost reaches 1.774 billion yuan.

· Produced water treatment process is complex, high investment, low treatment efficiency and high operating cost.

· Produced water from different blocks is treated centrally in the joint station, resulting in poor compatibility between reinjection water and reservoir, which affects waterflood development.

Implementation of pre-separation of water can improve economic benefits

The implementation of pre-separation of water, at the wellhead, well group, metering station or transfer station in advance to separate most of the produced water and meet the local treatment standards after re-injection, the remaining low water cut oil is sent to the joint station for centralized treatment, can simplify the process, save investment, reduce energy consumption and operating costs, and avoid large-scale expansion of the joint station.

There are problems with the pre-separation technology

The existing pre-separation device has a high oil content index (generally about 500mg/L, some up to 1000mg/L), so it is necessary to build a produced water treatment station to independently treat the produced water, which requires high investment, complicated process flow and heavy management workload.

It is impossible to achieve miniaturization and integration of facilities, and new construction requires land acquisition.

The problem of backwashing water source of the well site filter cannot be solved, so it is necessary to build a new well site backwashing water tank.

The low-cost and short-process integrated pre-separation technology (gas-liquid separation, water separation, and the produced water treatment to meet the water quality standards, local re-injection) can replace the traditional pre-separation device and the entire produced water treatment station, saving 50% of the investment, 70% of the land area, 60% of the operating cost than the traditional process technology, and has obvious advantages. Using deep bed filtration and in vitro scrubbing technology, the filtration accuracy and backwashing effect of the filter bed are greatly improved. Strong scrubbing, good backwash effect, no need to connect to external backwash water source.