Ultra-low permeability oil layer protection drilling fluid for horizontal well
A technology for oil layer protection and drilling fluid, applied in the field of ultra-low permeability oil layer protection drilling fluid, can solve problems such as oil layer damage, increase oil drainage area, solid phase particle invasion, etc., to protect oil layer, reduce reservoir damage and system stability Effect
Active Publication Date: 2012-03-07
PETROCHINA CO LTD
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Problems solved by technology
[0003] The production of a single well in an ultra-low permeability oil layer is relatively low, and the production of a single well in a vertical well is generally 2-5 tons per day. However, the drilling cycle of horizontal wells is relatively long, and the contact time between the drilling fluid and the oil layer is long, which requires that the drilling fluid does little damage to the oil layer and can better protect the oil layer
The solid phase content of the existing drilling fluid is relatively high, and the solid phase particles invade the pores of the oil layer, which is easy to cause damage to the oil layer. In addition, the viscosity increaser and fluid loss reducer of the existing drilling fluid are polymers, which are easy to cause blockage to the oil layer
Method used
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Embodiment 1
[0013] Add 1000 grams of water to the mixer, add 20 grams of sodium bentonite while stirring, and age for 10 hours after stirring; after aging, add 20 grams of carboxymethyl starch ether, 30 grams of potassium formate, 8 grams of ammonium chloride, 4 grams of carboxymethyl cellulose, 5 grams of glass microspheres, 0.5 grams of formaldehyde, and 1 gram of magnesium oxide. Stir evenly to obtain the oil reservoir drilling fluid of the present invention.
[0014] The raw materials used in this example can be bought from the market.
[0015] See Table 1 for performance indicators and Table 2 for static damage evaluation of anhydrous kerosene
[0016] Table 1
[0017] project index Density ρ(g / cm 3 ) 1.03 API water loss (ml) 6 pH 9.0 Apparent viscosity AV(mPa·s) 31 Plastic viscosity PV(MPa·s) 20 Dynamic shear force YP(mPa) 11 Dynamic plastic ratio YP / PV 0.55 Funnel Viscosity FV(S) 59
[0018] Table 2
[0019]
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Abstract
The invention relates to ultra-low permeability oil layer protection drilling fluid for a petroleum drilling horizontal well. The drilling fluid comprises the following raw materials in parts by weight: 100 parts of clear water, 2 parts of sodium base bentonite, 2-3 parts of carboxymethyl starch ether, 2-5 parts of pctassium formate, 0.5-1 part of bis-trimethyl ethyl ammonium chloride, 0.3-0.8 part of carboxymethylcellulose, 0.5-1 part of glass microballon, 0.05 part of formaldehyde and 0.1 part of magnesium oxide; the apparent viscosity of the drilling fluid is 31mPa.s, the plastic viscosityis 20mPa.s, and the API water loss is 6 milliliters; the well drilling construction requirements are satisfied; static injure evaluation experiments are carried out on four blocks of ultra-low permeable reservoir cores by anhydrous kerosene, the average injury rate is 9.68%, and the injury belongs to mitigated injury; and the system of the drilling fluid is stable, has slight injury to the reservoir, can protect oil reservoir, and is especially suitable for ultra-low permeability oil layer.
Description
technical field [0001] The invention relates to an ultra-low permeability oil layer protection drilling fluid used for oil drilling horizontal wells. Background technique [0002] Ultra-low permeability oil layer means that the absolute permeability is less than 10×10 -3 μm 2 The oil layer is very sensitive to the damage of drilling fluid. If the oil layer is not properly protected during the drilling process, the oil well production will be seriously affected. [0003] The production of a single well in an ultra-low permeability oil layer is relatively low, and the production of a single well in a vertical well is generally 2-5 tons per day. However, the drilling cycle of horizontal wells is relatively long, and the contact time between the drilling fluid and the oil layer is long, which requires that the drilling fluid does little damage to the oil layer and can better protect the oil layer. Existing drilling fluids have a relatively high solid content, and solid partic...
Claims
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IPC IPC(8): C09K8/20
Inventor 吴学升王定峰欧阳勇高云文王勇茗
Owner PETROCHINA CO LTD