A Low Friction Reservoir Protection Cement Slurry

Abstract

The application provides cement paste protected by a low-friction resistivity reservoir. The cement paste comprises the following components in parts by weight: 100 parts of oil well cement, 0-40 parts of silica powder, 24-100 parts of coal ash, 20-72 parts of reinforcing agent, 3-6 parts of high-temperature fluid loss agent, 0-4 parts of retarder, 0.5-1 part of defoamer, and 60-185 parts of fresh water, wherein the density of the cement paste is between 1.50 g / cm<3> and 1.85 g / cm<3>; proper density can be regulated and selected according to the formation condition; the cost per cubic centimeter is just 1 / 3 of that of a floating bead system, and is about 80% of the cost of conventional cement paste with the density of 1.90 g / cm<3>. Therefore, the production cost is greatly saved. In addition, long open hole cementing can be achieved; low-density and high-strength cement paste system of floating beads, a single-click and double-seal cementing process, and a system of taking general soil slurry as first slurry and heightening a density tail rotor can be replaced; the advantages of low cost, high cement strength, safety and environmental protection are integrated.

Description

technical field [0001] The invention relates to the field of drilling and cementing in oil fields, in particular to a low-friction reservoir protection cement slurry for oil and gas reservoirs. Background technique [0002] Jinzhou 9-3 Oilfield and Qinhuangdao 32-6 Oilfield where CNOOC Tianjin Branch is located have multiple pressure systems, serious reservoir energy depletion, narrow safe density window, adjustment wells adopt highly deviated wells and horizontal wells develop. [0003] In terms of well cementing, due to the long open hole and high annular friction, the cement slurry is easy to leak and easily pollute the reservoir; due to the need for long open hole sealing, the temperature difference between the bottom and the wellhead is large, and it is urgent to maintain the wellhead cement in the case of a large temperature difference. Early strength at low temperature; due to multiple pressure layers, it is difficult to stabilize the pressure, and the cement slurry ...

AI Technical Summary

Problems solved by technology

[0005] 1. Conventional 1.90g / cm 3 The hydrostatic column pressure of the cement slurry is high, and the annular friction resistance of the long open hole section is large. For the section with severe reservoir energy depletion, the formation is likely to rupture during the cementing process, and the cement slurry will pollute the production layer;

[0006] 2. The annular gap of the liner pipe is small, and the use of fiber plugging materials is likely to cause formation blockage, and the construction risk is high, which may cause cementing failure;

[0007] 3. If the low-density hollow floating beads cement slurry system is used, because the floating beads are large and hollow, the slurry is easy to break and thicken in the long open hole section, and the annular friction is 1.90g / cm compared to the conventional one. 3 Even larger, it is also easy to cause formation rupture, resulting in cement slurry pollution production layer

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