Methods of Improving Recovery of Strongly Sensitive Heavy Oil Reservoirs

Abstract

The invention provides a method for improving the recovery rate of highly sensitive heavy oil reservoirs, which utilizes high-temperature clay stabilizers, slow-release acid liquid systems, high-efficiency oil displacement agents and carbon dioxide in the development of sensitive heavy oil reservoirs to improve Single well development effect, a new method to improve the recovery of sensitive heavy oil reservoirs. The technical plan is: firstly use the temperature-sensitive slow-release acid system to treat the pollution near the wellbore, then inject liquid carbon dioxide, use high-temperature clay stabilizer to protect the oil layer before steam injection, and inject high-temperature oil displacement during steam injection Dosage system. Then, after the well is closed and the well is soaked, the well is opened and the blowout is released, the pump is lowered into the well for continuous oil recovery. The field test shows that the average periodic oil-steam ratio of vertical wells reaches 0.4, the average periodic oil-steam ratio of horizontal wells reaches 0.6, and the periodic oil production exceeds 1000t. Laboratory experiments show that the development of this invention in sensitive heavy oil reservoirs involves technology, oil The final recovery rate of the reservoir can reach more than 35%.

Description

technical field [0001] The invention relates to an oilfield exploitation technology, in particular to a combination application of a high-temperature clay stabilizer, a slow-release acid solution system, a high-efficiency oil displacement agent and carbon dioxide in the development of sensitive heavy oil reservoirs to improve the development effect of a single well and increase the sensitivity A new method for the recovery of heavy oil reservoirs. Background technique [0002] With the massive consumption of conventional oil and gas resources and the rising demand for oil, heavy oil resources have become the main potential for lower development due to their wide distribution, huge reserves, and low reserves utilization rate. Domestic heavy oil resources are very rich, and the estimated proven reserves are 8 billion tons. Of the 2.06 billion tons of proven heavy oil reserves, 701 million tons are unused geological reserves. A considerable part of the undeveloped heavy oil re...

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Problems solved by technology

[0003] ⑴ High clay content, strong water sensitivity, difficult oil layer protection

[0005] (2) The oil layer is thin, the net-to-gross ratio is low, and the heat utilization rate of steam huff and puff is low

[0006]Because the oil layer is thin, the heat loss of the steam injected into the oil layer from the upper and lower cover layers increases, the lateral sweep volume of the oil layer becomes smaller, and the heat utilization rate decreases; in addition, the net total The heat ratio is also an important factor affecting the heat utilization rate. Due to the existence of the thin muddy interlayer, the heat loss in the oil layer increases, and part of the heat is consumed in the interlayer.

When the effective oil layer thickness and steam injection rate are the same, as the thickness of the interlayer increases, that is, the net-to-total ratio decreases, the oil-steam ratio becomes significantly lower, mainly because the heating radius of the oil layer becomes smaller, the heat utilization rate is low, and the throughput effect becomes smaller. Difference

[0007] (3) Crude oil has high viscosity, insufficient natural energy, and poor liquid supply capacity of oil wells

Both chemical cold recovery and conventional thermal recovery will produce a large amount of liquid entering the well, and the serious water sensitivity of the reservoir will lead to a huge loss of permeability. The failure of injection and production is an important system of this contradiction. Even if the anti-swelling hand is used before the process , the permeability damage caused during the drilling and completion process cannot be restored

In addition, the oil layer in the block is thin, the net-to-gross ratio is low, the heat loss is huge during thermal recovery development, and the thermal efficiency utilization rate is less than 40%. In addition, the reservoir energy is scarce and the recovery pressure is insufficient, resulting in a short thermal recovery production cycle and poor economic benefits.

[0010]Therefore, among the above-mentioned undeveloped sensitive heavy oil reserves, especially sensitive heavy oil reservoirs with a water sensitivity index greater than 90% and a layer thickness less than 6m are scarce It is of great practical significance to alleviate the conflict of crude oil demand and ensure the development of the national economy to explore the economic development mode of this type of oil reservoir with mature and supporting production technology, and to increase the degree of production and recovery of the corresponding reserves.

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