A plugging material and plugging slurry for protecting low-pressure fractured reservoirs

Abstract

The invention discloses a plugging material and plugging slurry for protecting a reservoir stratum with the low fracturing fracture ability. The plugging material is prepared from, by weight, 5-6 parts of walnut shell powder, 2-3 parts of a composite plugging agent, 1.5-2 parts of an agent for plugging while drilling, 4-5 parts of an acid soluble plugging agent, 4-5 parts of a high-dehydration-rate plugging agent and 0.2-0.3 part of calcium oxide. The natural plant inertia material, the fiber plugging agent and the acid soluble plugging agent are mixed according to the certain matching ratio to form the acid soluble plugging material in granule and fiber shapes. The material has the advantages that the bridging effect of a bridging material is good and the plugging success rate is high, and also has the advantages that the density is low, stratum pressure is effectively balanced, the stratum damage is small, the plugging property is strong and acid solubility is achieved. The plugging slurry prepared from the plugging material and water has the advantages of being low in density, high in pressure bearing capability, good in malignant leakage plugging effect, high in acid solubility and the like; the on-site preparation process is simple, construction is safe and reliable, and the purposes of reducing well leakage loss and protecting the reservoir stratum can be achieved.

Description

Technical field [0001] The invention belongs to the technical field of plugging for petroleum drilling, and specifically relates to a plugging material for protecting low-pressure fractured reservoirs, and also relates to a plugging slurry for protecting low-pressure fractured reservoirs. Background technique [0002] Lost circulation is when the fluid column pressure in the wellbore is greater than the formation fracture pressure or the formation pores or fractures are drilled, causing the fluid in the well to enter the formation on a large scale. It is the most common and most difficult problem in drilling engineering. , Not only delays the drilling operation time, prolongs the drilling cycle, and causes huge economic losses, but also the solid particles in the mud (including clay, weighting agent, treatment agent and fine drill cuttings) will be in the narrow throat of the oil and gas channel of the reservoir. The channels are piled up, and part of the circulation channels are...

AI Technical Summary

Problems solved by technology

[0004] However, for low-pressure fractured reservoirs, the existing plugging materials face the following problems: on the one hand, due to the large amount of leakage and the large particle size range of the plugging materials, there is a certain blindness in the compounding of the plugging materials , resulting in a low plugging success rate; on the other hand, due to the low reservoir pressure gradient, plugging materials are likely to aggravate the destruction of formation equilibrium pressure, increase the liquid column static pressure, increase the width of natural fractures, and aggravate the degree of leakage; the third aspect , it is difficult to unplug during the reservoir reconstruction stage, causing pollution to the reservoir

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