Expandable graphite plugging agent system for deep channel blocking of heavy oil reservoir steam flooding and injection method

Abstract

The invention relates to an expandable graphite plugging agent system for deep channel blocking of heavy oil reservoir steam flooding. The system comprises, by mass fraction of the total mass of the plugging agent system, 0.5%-1.0% of low-temperature expandable graphite particles, 0.4%-0.8% of medium-temperature expandable graphite particles, 0.3%-0.6% of high-temperature expandable graphite particles, 0.1%-0.2% of carrying fluid, and the balance fluid preparation water; and the carrying fluid is a non-ion polymer water solution, and the mass fraction sum of all the components is 100%. According to the expandable graphite plugging agent system for deep channel blocking of the heavy oil reservoir steam flooding, the temperature-resisting non-ion polymer water solution serves as the carrying fluid, the graphite particles with different initial expansion temperatures are carried into a deep stratum, and according to the distributing characteristics of the temperature gradient field of a steam flooding steam channel, the graphite particles with the different initial expansion temperatures slowly expand, so that deep channel blocking for the steam flooding steam channel is achieved, and further the swept volume of the steam flooding is enlarged.

Description

technical field [0001] The invention belongs to the field of oil field chemistry, and in particular relates to an expandable graphite plugging agent system and an injection method thereof for deep steam channeling of heavy oil reservoirs. [0002] technical background [0003] my country is rich in heavy oil resources, accounting for about 30% of the total oil reserves, and steam injection is the main way of heavy oil reservoir exploitation. For unconsolidated sandstone heavy oil reservoirs or heavy oil reservoirs with fractures, after long-term steam flooding, the formation forms a dominant seepage channel, which makes the injected steam escape along the high-permeability layer, and the swept volume of steam decreases, resulting in oil wells containing As water volume rises, yields fall. Prevention and control of steam channeling by steam flooding is an important way to improve the sweep efficiency of steam flooding in heavy oil reservoirs and a problem to be solved urgentl...

AI Technical Summary

Problems solved by technology

Due to the short effective period of high-temperature foam, fast jelly formation, and poor migration of inorganic particles in conventional steam channeling measures, the deep channeling technology of steam flooding in heavy oil reservoirs is facing great challenges

High-temperature foam sealing agents mainly include temperature-resistant foaming agents such as alkylbenzene sulfonate and α-olefin sulfonate, which can improve steam (water) flooding sweep coefficient and oil displacement efficiency, but high-temperature foam construction is relatively complicated. Poor controllability in formation, short validity period

In addition, for long-term steam-flooded high-temperature formations, the stability of the foam drops sharply, reducing the channel sealing effect

High-temperature jelly-type channeling agents are mainly composed of heat-resistant polymers, tannin extracts (modified tannin extracts), lignin and other systems and aldehyde cross-linking agents, which can withstand temperatures of 200°C, but due to excessive concentration, the cost In addition, due to the high formation temperature (≥150°C), the gelation time of the jelly-type blocking agent system is generally less than 10 hours, resulting in poor deep migration ability of the jelly-type plugging agent system, and it is impossible to realize deep steam sealing. Channeling; granular plugging agents mainly include inorganic rigid particles such as ultra-fine cement and clay. Such plugging agents have poor mobility and are often deposited near the wellbore. It is difficult to achieve deep sealing of steam and is sensitive to temperature. The consolidation time of the plugging agent system is short, and there are certain engineering risks in the construction process

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