Jianghan Oilfield intensive farming "experimental field" to improve oil recovery

News from Sinopec News "After five years of research and research, the polymer flooding field test has achieved initial results: At present, the injection pressure in the test area has increased by 1 MPa, the water cut of the well group has dropped by 3%, and the production has shown an upward trend, especially The key wells of the central well have been effective
.

” On August 5, Jianghan Oilfield Research Institute tertiary oil recovery expert He Jianhua said

After decades of development, Jianghan Oilfield has a comprehensive water cut of 90.
2% and a recoverable reserve of 87.
4%, but the average oil recovery rate is only 24.
9%
.

In this regard, the oilfield prefers "experimental fields" to carry out new technology tests, exploring polymer flooding for waterflooding heavy oil, exploring chemical cold recovery for thermal recovery heavy oil, and exploring pulse injection and production for low-permeability, medium- and high-water-cut oil reservoirs in order to further increase the recovery.

Magic polymer and calcium and magnesium ions "turn enemies into friends"

Polymer flooding refers to adding polymer to the injected water to reduce the oil-water mobility ratio and expand the swept volume, thereby increasing the recovery factor
.

The implementation of polymer flooding has always been the dream of Jianghan Oilfield, but for many years, due to reservoir conditions, the dream has not become a reality

In recent years, the Research Institute of Petroleum Exploration and Development has cooperated with Jianghan Oilfield to research and develop a suspension microcrystalline polymer system, which makes the polymer change from being afraid of calcium and magnesium ions to using calcium and magnesium ions to increase viscosity and increase efficiency.
The high content of calcium and magnesium ions in the Bamianhe oil area is not suitable for polymer flooding
.

However, after only 10 days of on-site polymer injection, they found that the pressure of the injection equipment was abnormally high, and the wellhead displacement dropped rapidly, and the first time it was judged that it was caused by the fouling and blockage of the static mixer
.

Opening the static mixer found that a large amount of sediment almost blocked the pipeline

　　In April this year, the polymer flooding project in Block Mian 1 entered the full polymer injection stage.
A total of 37 tons of polymer and 190 tons of viscosity enhancer have been injected.
The average water cut of the five wells in the eastern part of the well group has dropped from 98.
3% to 93%.
The oil volume has risen from 5.
2 tons to 8.
2 tons, which initially achieved good results
.

　　Let heavy oil "from chronic to impatient"

　　The thermal recovery heavy oil reserves of Bamianhe Oilfield is 39.
3 million tons.
It has been huffed and puffed for 3 to 6 rounds, and the recovery rate is only 11%.
However, problems such as flooding and steam channeling have started to appear one after another, and the thermal recovery effect and benefit are getting worse and worse
.

　　"Heavy oil is difficult to recover because of its poor fluidity.
The main reason is that the content of asphaltenes and gums is too high.
The properties of heavy oil must be changed
.

" He Jianhua said, "It's a bit like changing a person's character, turning a chronic person into an impatient person.

　　They have developed an "active" self-diffusing polymer viscosity reducer, which brings polar groups into the heavy oil, opens up the stacking structure of asphaltenes and gums, weakens the interaction between heavy components, and achieves thickening.
Oil viscosity reduction
.

In the indoor evaluation, the dynamic viscosity reduction rate of the viscosity reducer with a concentration of 3.

　　At present, this water-soluble viscosity reducer has been implemented for 6 well times, and the oil has increased by more than 1,000 tons within the validity period.
The input-output ratio has reached 1:1.
1 at an oil price of 40 US dollars/barrel, and the economic efficiency of the measures has reached 100%
.

　　In the next step, they will actively learn cold production viscosity reduction and flooding technology from Shengli Oilfield, optimize formulas, reduce costs, and strive to realize the transition from throughput to displacement as soon as possible
.

　　Pulse injection allows more oil to be replaced by water

　　The ultra-low permeability reservoirs of Pingbei Oilfield have entered a period of rapid water cut.
Among them, the water cut of the SP199 well area has risen from 55% in 2008 to 73% at present
.

In response to this, Jianghan Oilfield has carried out research on the integration of physical model and digital model to tackle the pulse injection and production technology

　　Pulse injection and production is to realize the full replacement of formation fluid by adjusting the injection parameters of the water well, so that more oil is replaced by water, and at the same time optimize the parameters of the oil well, realize the uniform adjustment of the pressure field and the flow field, and achieve the purpose of water control and oil stabilization
.

　　Pingbei Oilfield adopts pulse injection and production with 15 days of injection and 30 days of stoppage.
Since the beginning of this year, 120 water wells have been implemented, covering 14.
34 million tons of reserves.
The water cut of the SP199 well area in the core area has dropped by 2.
6 percentage points, and the block has increased daily oil by 4.
9 tons
.

　　In the next step, they will focus on research on pulse injection-production pressure conduction, remaining oil distribution rules, and field dynamic tracking evaluation, and continue to improve the pulse injection-production adjustment model for low-permeability reservoirs
.

(Shi Jianfen, Wu Hua, Zhu Shouli)