Tuha Santanghu Oilfield "Imbibition + Displacement" Awakens Shale Reservoirs

China Petroleum Network News (Reporter An Fengxia, Correspondent Li Shirui) As of October 28, the six well groups in the Santanghu shale oil field of Tuha Oilfield have increased their oil production by more than 3,000 tons this year, with an average daily increase of 15.5 tons. This is due to the implementation of the new "imbibition + displacement" technology.

The shale oil reservoir in the Ma 1 block of Santanghu Oilfield has the characteristics of low porosity, ultra-low permeability, and medium oil saturation. Its accumulation is controlled by high-quality source rocks and favorable phase belts. It is a typical shale oil reservoir with integrated source and reservoir. Compared with domestic shale oil, the shale oil in the Ma 1 block of Santanghu has a slightly lower maturity, a lower proportion of sweet spot thickness, and a lower pressure coefficient.

Previously, after the implementation of "horizontal well + volume fracturing" development of shale oil in the Ma 1 block, the reserves were effectively mobilized, but due to the lack of mature and supporting formation energy replenishment methods, it was difficult to stabilize production and the output decreased rapidly. In the absence of experience to learn from, the technical personnel did not wait or rely on others, but adhered to the development concept of "innovation has no limits, exploration has no taboos", and around the problem of how to replenish shale oil, through in-depth research on shale oil reservoir characteristics, core conditions, fracture network development characteristics and injection and production dynamic characteristics, innovatively proposed the "imbibition + displacement" technology to enhance recovery.

The large proportion of micro-nano pore throats in shale oil reservoirs determines that conventional water drive cannot mobilize crude oil in tiny pores, while the "imbibition + displacement" recovery enhancement technology can effectively make up for the shortcomings of conventional water drive that are difficult to mobilize crude oil in tiny pores, and has a better oil recovery effect. Relying on displacement to mobilize the remaining oil in large pores, relying on imbibition to mobilize the remaining oil in small pores, giving full play to the coupling effect of "imbibition + displacement" can realize the effective utilization of shale oil reserves and achieve the purpose of improving recovery.

Since the beginning of this year, Santanghu Oilfield has implemented a total of 6 "imbibition + displacement" test well groups in the Ma 1 block shale oil, and 5 well groups have achieved results, with an average daily increase of 3.1 tons per well group. At present, the increase in oil production of the 5 effective well groups is expected to be further improved. The successful test of the "imbibition + displacement" recovery technology has found a new path for significantly improving the recovery rate in the later stage of Santanghu shale oil development. It has become the first shale oil reservoir in Tuha Oilfield to stabilize and increase production through water injection, which has important reference significance for the efficient development of similar oil reservoirs in China.