Water plugging method for lower-layer water of thin-interlayer heavy oil reservoir and adopted water-plugging agent system

Abstract

The invention relates to a water plugging method for lower-layer water of a thin-interlayer heavy oil reservoir and an adopted water-plugging agent system, and belongs to the technical field of oil exploitation. The water plugging method comprises the following steps: a nitrogen foam slug is injected into a water outlet oil layer to restrain the lower-layer water from invading into an interlayer;then an interlayer gel slug is injected and mainly composed of water glass, a water glass cross-linking agent and water, the interlayer gel slug enters the interlayer, and after gelatinization, poresin the interlayer are plugged; and then a plugging gel slug is injected and mainly composed of alkali lignin, an alkali lignin cross-linking agent and water, the plugging gel slug enters the boundaryof the oil layer and the interlayer, and after gelatinization, the boundary of the oil layer and the interlayer is plugged. According to the water plugging method for the lower-layer water of the thin-interlayer heavy oil reservoir, the three slugs are adopted to mainly plug the lower part of the oil layer, the interlayer and the upper part of a water layer, the lower-layer water is restrained from running into the oil layer, and the development effect on the thin-interlayer heavy oil reservoir is improved.

Description

technical field [0001] The invention relates to a method for shutting off water in the lower layer of a thin interlayer heavy oil reservoir and a water shutoff agent system used, belonging to the technical field of petroleum exploitation. Background technique [0002] The implementation of the water shutoff technology mainly includes two important steps: selecting the water shutoff agent and running the water shutoff agent into the well. After selecting a suitable water shutoff agent, the water shutoff agent needs to be solidified and gelled to play a water shutoff effect, which is a key step for the water shutoff agent to be effective. Reservoir conditions and well completion methods have an impact on the location of the plugging agent, especially in horizontal wells where bottom water and fracture seepage are the main water, and the water flooded part is closely connected with the oil layer, and open hole completion and other methods make the formation and annular parts T...

AI Technical Summary

Problems solved by technology

[0003] The existing water plugging agents mainly use granular, resin, gel, and foam plugging agents. The solid particle type plugging agents have poor migration ability and cannot pass through sand control screens, and cannot achieve deep formation plugging; resin type plugging agents The plugging agent is sensitive to the environment, difficult to control, and high in cost; the plugging strength of the foam type plugging agent is low; the conventional gel type plugging agent mostly uses polymer as the main agent, and the viscosity of the base fluid is high, so it is difficult to enter the channel of water channeling

[0004] In heavy oil reservoirs with thin interlayers, the energy of the lower layer water is sufficient. Because the interlayer is thin and has a certain permeability, with the steam injection production, the lower layer water can easily pass through the interlayer and enter the oil layer, resulting in rapid water flooding of the oil layer. , Most oil wells are produced with high water cut. During the steam injection process, the steam enters the water layer along the water channeling channel, and the steam utilization rate is low, which increases the production cost and affects the development effect of such oil wells.

[0005] For heavy oil reservoirs with thin interlayers, because the interlayers have a certain shielding effect on the lower water, the physical properties of the oil layers are relatively poor, and it is difficult for conventional plugging agents with high viscosity to enter the interlayers, so they can only form plugging in the oil layers. After plugging, it is easy to form secondary water channeling, and the effect is poor

[0006] When the existing plugging agent system is used for water plugging in thin interlayer heavy oil reservoirs, it is difficult to balance the relationship between plugging strength and plugging agent base fluid viscosity, and the plugging effect on the water outlet point of thin interlayer heavy oil reservoirs is limited