Kureha Corporation

Toppan Printing Co., Ltd.

Masayuki Okura

Hiroyuki Sato

Shinya Takahashi

Takeo Takahashi

Hikaru Saijo

Katsumi Yoshida

Takuma Kobayashi

Masahiro Yamazaki

Yuko Sekimori

Fuminori Kobayashi

Takahiro Watanabe

Yusaku Inaba

Mototaka Kawashima

Hukaru Saijo

A stock shape for a downhole tool component includes a magnesium alloy including a phase containing 70 to 95 wt. % of magnesium in which 0 wt. % or more and less than 0.3 wt. % of a rare earth metal, a metal material other than the magnesium and the rare earth metal, and 0.1 to 20 wt. % of a degradation accelerator are distributed, and the stock shape has an average particle size of the metal material of 1 to 300 &#x3bc;m, tensile strength of 200 to 500 MPa, and a degradation rate in a 2% potassium chloride aqueous solution at 93&#xb0; C. of not less than 20 mg/cmand not greater than 20000 mg/cmper day. Accordingly, a downhole tool having high strength and being readily degradable is established.

Stock shape for downhole tool component, downhole tool component, and downhole tool

A downhole tool member for hydrocarbon resource recovery, comprising a shaped body of a polyglycolic acid resin having a weight average molecular weight of at least 70,000, having an effective thickness which is &#xbd; or more of a critical thickness of surface decomposition, and exhibiting a thickness reduction rate in water which is constant with respect to time. As a result, it has become possible to more accurately design the strength and time up to the collapse of the downhole tool member which forms the whole or a part of a downhole tool for developing or repairing downholes for recovery of hydrocarbon resources, such as oil and gas.

Downhole tool member for hydrocarbon resource recovery

A plug for well drilling includes a mandrel and at least one diametrically expandable annular rubber member and at least one slip disposed on an outer circumferential surface orthogonal to an axial direction of the mandrel; (i) the mandrel being formed from a degradable material; and (ii) the at least one diametrically expandable annular rubber member being formed from a degradable rubber material having a rate of decrease of not less than 5% in 50% strain compressive stress after immersion in water at a temperature of 150&#xb0; C. for 24 hours relative to the compressive stress before immersion; and/or having a rate of loss of mass of from 5 to 100% after immersion in water at a temperature of 150&#xb0; C. for 72 hours relative to the mass before immersion. A well drilling method includes a step of isolating a borehole using the plug for well drilling, part or all of the plug being degraded thereafter.

Plug for well drilling provided with diametrically expandable annular rubber member formed from degradable rubber material

Provided is a rubber member for downhole tools, of which a decrease rate of 50% strain compressive stress after immersion for 24 hours in 150&#xb0; C. water relative to 50% strain compressive stress before immersion is not less than 5%, and preferably not less than 50%. The rubber member is suitable for a seal member, ball sealer, ball seat, and a protecting member. Also provided is a downhole tool comprising the rubber member, and a method for recovering a hydrocarbon resource using the downhole tool.

Rubber member for downhole tools, downhole tool, and method for recovering hydrocarbon resource

A degradable rubber member for a downhole tool formed from a rubber material containing from 0.1 to 20 parts by mass of a degradation accelerator relative to 100 parts by mass of a degradable rubber (optionally containing other rubber materials and/or reinforcing materials), of which, preferably, the decrease rate of the mass or the 50% strain compressive stress after immersion for 24 hours in 150&#xb0; C. water is not less than 5%, and/or the mass loss rate after immersion for 72 hours in 150&#xb0; C. water is from 5 to 100%, and further, as desired, the tensile fracture strain at 66&#xb0; C. is not less than 50%, the 70% strain compressive stress is not less than 10 MPa, and the compressive fracture strain is not less than 50%; a degradable seal member or a protecting member for downhole tools comprising such a rubber member; and a downhole tool such as a plug for well drilling, and a method for well drilling.

Degradable rubber member for downhole tools, degradable seal member, degradable protecting member, downhole tool, and method for well drilling

A degradable seal member for downhole tools, the member being a diameter-expandable annular seal member, the diameter-expandable annular seal member comprising: two or more annular members distributed along an axial direction, the annular members being formed from a degradable polymer material having hardness in a range from A60 to D80; a plug for well drilling; and a method for well drilling using the degradable seal member for downhole tools.

Diameter-expandable annular degradable seal member for downhole tool, plug for well drilling, and method for well drilling

A poly-L-lactic acid (PLLA) solid-state extrusion molded article having a weight average molecular weight of from 100,000 to 380,000 and a melt viscosity of from 20 to 2,000 Pa&#xb7;s (at a temperature of 240&#xb0; C. and a shear rate of 120 sec) and having an L-form content of from 80 to 100%, the article having a thickness or diameter of from 10 to 500 mm and a tensile strength of from 5 to 100 MPa at a temperature of 66&#xb0; C. (the article may contain a filler and have a tensile strength of from 5 to 200 MPa); a downhole tool member or a ball sealer for well drilling and completion formed by machining the solid-state extrusion molded article; an isolation plug provided with the downhole tool member; and a production method for a PLLA solid-state extrusion molded article comprising steps of supplying a resin material containing a PLLA to an extruder, solid-state extrusion molding the material, pressurizing the solid-state extrusion molded product, drawing the pressurized product while applying a back pressure in the direction of a forming die to suppress the expansion of the solid-state extrusion molded product; and a well drilling and completion method.

Poly-L-lactic acid solid-state extrusion molded article, method for producing the same, and use applications of the same

Member for hydrocarbon resource collection downhole tool

A solidification- and extrusion-molded article of polyglycolic acid, which is formed of a resin material containing polyglycolic acid, the polyglycolic acid having a melt viscosity of 200 to 2,000 Pa&#xb7;s, and has a thickness or diameter of greater than 100 mm but not greater than 500 mm. A downhole tool or a component thereof and a ball sealer for petroleum excavation are formed by cutting the solidification- and extrusion-molded article. A method for manufacturing the solidification- and extrusion-molded article of polyglycolic acid and a method for manufacturing a ball sealer for petroleum excavation.

Solidification- and extrusion-molded article of polyglycolic acid and method for manufacturing same

Described are a molded product having an effective thickness of 1 mm or more, the molded product being formed from an aliphatic polyester resin composition containing from 1 to 30 parts by mass of a carboxylic acid anhydride and preferably further containing from 1 to 50 parts by mass of at least one type of a short fiber reinforcing material, a thermoplastic elastomer, or an acrylic rubber core-shell polymer per 100 parts by mass of an aliphatic polyester resin containing not less than 50 mass % of a polyglycolic acid resin, the effective thickness being 1 mm or more; a downhole tool for hydrocarbon resource recovery formed from the molded product having an effective thickness of 1 mm or more; an aliphatic polyester resin composition for the downhole tool member for hydrocarbon resource recovery; and a well drilling method.

Molded product having effective thickness of 1 mm or more and containing aliphatic polyester resin, and downhole tool member for hydrocarbon resource recovery

A ball sealer for hydrocarbon resource recovery, characterized by being obtained by coating a spherical core that comprises at least one layer comprising a disintegrable aliphatic polyester resin with a resin material that has higher impact resistance than the aliphatic polyester resin and by having a diameter of not less than approximately 25 mm (1 inch). This ball sealer has a large diameter, retains the property of being disintegrable after fracturing, and has impact resistance which makes the ball withstand high-velocity loading. The sealer is suitable for use in hydraulic fracturing, which is commonly used for recovering hydrocarbon resources including petroleum and gases. This large-diameter ball sealer can be efficiently formed with high dimensional accuracy by a method including at least one insert injection molding step.

Ball sealer for hydrocarbon resource recovery, method for manufacturing same, and method for treating borehole using same

A well treatment method characterized by disintegrating an elastic material by contacting a seal member for downhole tools comprising the elastic material with a well treatment fluid (acids such as hydrochloric acid, formic acid, acetic acid, and hydrofluoric acid, alkalis, hot water, steam, organic solvents, and the like).

Well treatment method by disintegrating elastic material by contacting seal member for downhole tools comprising elastic material with well treatment fluid

A plug for well drilling process comprising: (a) a mandrel formed from a degradable material; (b) a pair of rings placed on an outer peripheral surface existing in the orthogonal to an axial direction of the mandrel, at least one of the rings being formed from a degradable material; and (c) at least one diameter-expandable circular rubber member placed at a position between the pair of rings on the outer peripheral surface existing in the orthogonal to the axial direction of the mandrel; the percentage of mass loss in the degradable material after immersion for 72 hours in water at a temperature of 150&#xb0; C. preferably being from 5 to 100%; and a well drilling method comprising the step of plugging well hole using the plug for well drilling process, wherein part or all of the plug for well drilling process degrades after the plugging.

Plug for well drilling process provided with mandrel formed from degradable material

A ball sealer for hydrocarbon resource recovery, comprising: a generally spherical entire structure including at least two layers of a spherical core and a surface resin layer covering the spherical core, of which at least the surface resin layer comprises a polyglycolic acid resin; and having a diameter of at least about 25 mm (1 inch). The ball sealer is produced through a process comprising the steps of: disposing a spherical core by a support pin at a substantially central position within a mold cavity, injecting a surface resin comprising a polyglycolic acid resin into the cavity surrounding the spherical core, causing the support pin to retreat up to a wall surface of mold cavity in synchronism with a completion of the injection of the surface resin, and then hardening the surface resin. As a result, it is possible to produce a large-diameter ball sealer suitable for use in the hydraulic fracturing process (hydraulic fracturing) widely used for recovery of hydrocarbon resources by using a polyglycolic acid resin which is a biodegradable resin having good mechanical strengths and a good size designability at least as a surface-forming resin, through relatively simple steps and with good dimensional accuracy.

Ball sealer for hydrocarbon resource collection as well as production method therefor and downhole treatment method using same

A downhole tool member for hydrocarbon resource recovery, comprising a shaped body of a polyglycolic acid resin blended with an inorganic or organic short fiber reinforcement material, and having thickness reduction rate characteristics when held in water at 120&#xb0; C., inclusive of: an initial thickness reduction rate (as an average for a holding period for 4 hours) which is at most 0.8 times that of a shaped body of the polyglycolic acid resin alone, and has a terminal thickness reduction rate (after the thickness decreases to 50% or less of an initial thickness) which is larger than 1.5 times the initial thickness reduction rate.

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Tokyo, Japan

Masayuki Okura