Effective production process for shallow medium-high permeability super heavy oil reservoir

Abstract

The invention discloses an effective production process for a shallow medium-high permeability super heavy oil reservoir. The process comprises the following steps of emulsifying an oil-soluble viscosity reducer and water into O/W emulsion, wherein the stabilizing time of the emulsion is controlled to be over 2 days; injecting the O/W emulsion into an oil layer; closing a well for reaction, wherein the well closing time is over 3 days; and injecting steam and soaking the well. The injected oil-soluble viscosity reducer emulsion is a thermodynamic unstable system, so that the oil-soluble viscosity reducer is gradually released after construction is finished; and according to the principle of similarity and intermiscibility, the released oil-soluble viscosity reducer acts with crude oil to realize permanent viscosity reduction. The invention also discloses oil-soluble viscosity reducer emulsion which consists of the oil-soluble viscosity reducer and water containing a water-based emulsifier and is O/W emulsion. By the process, the super heavy oil reservoir is changed into a super heavy oil reservoir or even a common heavy oil reservoir in a production range, so that the injection amount of steam can be greatly reduced, energy consumption is greatly reduced, and the requirements of low cost and low energy consumption are met.

Description

technical field [0001] The invention relates to an effective production process for shallow medium-high permeability ultra-heavy oil reservoirs, and belongs to the technical field of petroleum exploitation. Background technique [0002] The core contradictions in the steam injection development process of shallow medium-high permeability ultra-heavy oil reservoirs are: first, due to shallow burial (≤800m) and low temperature (≤35°C), the reservoir temperature drops rapidly after steam injection; second, crude oil viscosity High (≥50000mPa.s), low permeability (≤800×10 -3 μm 2 ), the minimum temperature for the effective flow of crude oil must be above 60°C. The temperature field calculation results show that the radius of flowable oil at the end of steam injection is less than 10m, and the effective flow time is only 29d, which is much lower than 120d in the middle-deep ordinary heavy oil reservoir with a buried depth of 1200m and a reservoir temperature of 60°C. For supe...

AI Technical Summary

Problems solved by technology

For super heavy oil, based on the principle of similar miscibility, oil-soluble viscosity reducer has the best effect, while water-soluble viscosity reducer has poor adaptability to super heavy oil

However, since the oil-soluble viscosity reducer is currently injected in the form of stock solution, the sweeping range is small, and it is only used to treat the near-wellbore area, and cannot realize the viscosity reduction of ultra-heavy oil in a large area of ​​the reservoir

Therefore, even if the currently commonly used oil-soluble viscosity reducer and gas-assisted steam recovery (HDCS / HDNS technology) are used, there are still shortcomings such as short cycle production time after commissioning, low output, and low oil-steam ratio (less than 0.2). The production effect is poor and cannot be used effectively

However, oil-soluble viscosity reducer stock solution is directly injected into the reservoir in a large area to reduce the viscosity of ultra-heavy oil. It is technically feasible, but the economic cost is high, so it is not feasible.

Images