A universal fluid which includes a water-based drilling mud and a hydraulic material is used to drill a borehole and lay down settable filter cake. After drilling is completed, the filter cake and universal fluid are caused to solidify in selected parts of the borehole by admixing the universal fluid with an activator.

Universal fluids for drilling and cementing wells

This patent describes a method for solidifying an aqueous drilling fluid in a borehole. It comprises: admixing blast furnace slag with the drilling fluid; displacing the drilling fluid to a preselected location in the borehole; and allowing the drilling fluid to solidify in-situ.

Solidification of water based muds

This invention relates to a method of repairing holes, channels, voids and microannuli in a cement sheath situated in the annular space between a casing and the wall of a wellbore penetrating a subterranean earth formation, which method involves the use of a hydraulic cement consisting of discrete particles having a particle size not greater than about 30 microns The cement, which is utilized in a water slurry, has a low density, good thixotropic properties and, in one embodiment, expansive characteristics

Repair of microannuli and cement sheath

This invention relates to a method of repairing a hole in and thereby terminating the undesirable flow of fluid through a hole in a casing disposed in a wellbore penetrating a subterranean earth formation which method involves the same use of a hydraulic cement consisting of discrete particles having a particle size not greater than about 30 microns. The cement, which is utilized in a water slurry, has a low density, good thixotropic properties and, in one embodiment, expansive characteristics.

Repairing leaks in casings

This invention relates to a method of changing the direction of drilling a well bore wherein a cement plug is formed in the well bore at a location therein where the direction of drilling is to be changed and a pilot hole is drilled in the plug. The cement plug is formed using a slurry containing hydraulic cement consisting of discrete particles having a particle size not greater than about 30 microns. The use of such finely divided hydraulic cement significantly reduces the waiting time required for the slurry to develop sufficient compressive strength.

Well bore drilling direction changing method

A water-saturated soft soil is efficiently improved in its strength by incorporating thereinto an additive composed of ingredients A and B; the ingredient A comprises gypsum and the ingredient B comprises a mixture of 40-55% by weight of a Portland cement and 60-45% by weight of a water-granulated iron blast furnace slag having a particle size almost equal to or smaller than that of the Portland cement. The ratio by weight of the ingredient A to the ingredient B ranges from 10/90 to 30/70 and the total amount of the ingredients A and B used for the soft soil is sufficient to strengthen the soft soil.

Method for improving the strength of a water-saturated soft soil

A high water content soft soil, for example from the sea or river bed, may be improved in strength by incorporating thereinto an additive composed of ingredient A including a mixture of 5-45% by weight of gypsum and 95-55% by weight of a water-granulated iron blast furnace slag having an particle size within the range of 100-1 μm and ingredient B including a Portland cement. The ratio by weight of ingredient A to ingredient B is within the range of 75/25-55/45. Ingredient A is incorporated into the soft soil before incorporation of ingredient B.

Method for strengthening soft soil

PURPOSE: To increase effectively the strength of water-containing soft soil, by using, as a strength-increasing agent, fly ash modified with sulfuric acid, gypsum and Portland cement, allotting these materials into two additives, and prescribing the order of their addition, their proportions, and their particle sizes. CONSTITUTION: The strength-increasing additive 1[A]comprises two materials: fly ash (A 1 ) modified with sulfuric acid and gypsum or insoluble anhydrous gypsum (A 2 ). The strength increasing additive 2[B]comprises Portland cement. These additives are mixed and used to increase the strength of soft soil. If it is required to increase the deodorizing strength against the soft soil, a bivalent iron salt[C]is used as a third additive before adding additive B. The ratio of additive A to additive B is 50/50W25/75, while that of material A 1 to material A 2 is 70/30W20/80. The order of addition and mixing of materials A 1 and A 2 are arbitrary before additive B is added, but in practice, it is preferred to add and mix them at the same time in the form of a mixture. COPYRIGHT: (C)1983,JPO&Japio

Method of increasing strength of water-containing soft soil using fly ash modified with sulfuric acid

Artificial fish bank

PURPOSE:To increase the strength of wet soft ground by a method in which water-insoluble anhydrous gypsum and water-quenched fine slag powder are added to and mixed with wet soft ground and then the mixture is further mixed with Portland cement. CONSTITUTION:A wet soft ground is mixed with water-insoluble anhydrous gypsum and water-quenched fine slag powder of a grain size of 100-1mum, and then with Portland cement. In this case, the weight proportion of the insoluble anhydrous gypsum and the fine slag powder is 5/95-50/50, and also that of the insoluble anhydrous gypsum-fine slag mixture to Portland cement is 75/25-45/55. Also, the generation of offensive odor can be prevented by adding a water-soluble divalent iron salt to said mixture before the addition of Portland cement.

Ikuo Okabayashi

Papers

Method for improving the strength of a water-saturated soft soil

Method for strengthening soft soil

Method of increasing strength of water-containing soft soil using fly ash modified with sulfuric acid

Artificial fish bank

Increase of strength of wet soft soil