Plugging agent for drilling fluid and protecting low percolation reservoir

Abstract

The invention discloses a plugging agent for a drilling fluid and protecting a low percolation reservoir, comprising the following components of: 10-40 parts of acid-soluble fiber, 5-10 parts of oil-soluble resin, 30-60 parts of acid-soluble deformed particles, 5-10 parts of high-temperature resistant natural small molecule materials and 10-15 parts of calcium carbonate. The basic component of the plugging agent is the acid-soluble fiber which is swelled and soft, has good tenacity and can expand by adsorbing partial moisture, and the like in the drilling fluid to form a meshy structure so as to form plugging on a hole throat under the action of flowing pressure. In addition, other components in the plugging agent, such as the deformed particles, the natural small molecule materials and the calcium carbonate can combine with the fiber to play a rapid plugging role, and therefore, the plugging agent has low damage depth on the reservoir. The plugging agent can be matched with the radius of the hole throat of the low percolation reservoir according to the regulation on the radius of the hole throat of a low percolation core. A drilling fluid system using the plugging agent as the main plugging material has the dynamic core filtration rate not more than 0.1ml / 10min at high temperature and high pressure.

Description

technical field [0001] The invention belongs to temporary plugging material for petroleum drilling fluid. Background technique [0002] In the process of oil and gas field development, drilling fluid will inevitably enter the reservoir. For the development of oil and gas fields in low-permeability reservoirs, it has brought great difficulties. For low-permeability reservoirs with severe drilling fluid filtrate damage, reserve estimation is often inaccurate and productivity is extremely low or even non-productive. [0003] According to the comprehensive analysis, it is caused by the high flow resistance of the low-permeability reservoir itself, the damage caused by the drilling fluid to the low-permeability reservoir, and the blockage of the pore throat by solid phase invasion. [0004] In view of the above problems, the usual practice is to reduce the invasion depth by adding plugging agents into the drilling fluid; while conventional plugging agents are mainly aimed at me...

AI Technical Summary

Problems solved by technology

[0004] In view of the above problems, the usual practice is to reduce the invasion depth by adding plugging agents into the drilling fluid; while conventional plugging agents are mainly aimed at medium-high permeability cores, and for low-permeability reservoirs with small pore throats, conventional plugging agents The particle size is difficult to match with the pore throat size of the formation, and it is basically impossible to form a good inner mud cake. Simply improving the outer mud cake to improve plugging, so the plugging effect is not good, causing damage to low-permeability reservoirs

[0005] At present, there is no special storage and protection plugging agent for low permeability reservoir research.

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