This invention relates to a procedure to control fracture orientation in underground formations to increase well productivity. The method is performed by hydraulically fracturing the formation and propping and plugging the fractures which result. The formation is then perforated or notched in a direction angularly disposed relative to the anticipated fracture formation and first hydraulic fracture. The presence of the first fracture will force the second fracture to propagate in a direction away from that of the first fracture. A method for simultaneously fracturing the formation in two directions is also provided.

This invention relates to a method of determination of the deformation of the surface or subsurface of the earth resulting from an applied pressure change at a selected point, at a selected depth, in the earth, by measuring at least one physical parameter of the deformation above the point of application of pressure change. The method involves positioning a plurality of tiltmeters on or below the surface of the earth above the point of application of pressure change arranged in a known array, and measuring the change of angle of tilt of earth's surface or subsurface at the point of placement of each sensor while varying the pressure and flow rate of fluid into or out of the earth at the selected point. This invention further teaches how the individual values of incremental tilt at selected points on or below the earth's surface can be processed to determine material properties at selected points in the earth.

Artificial aquifers for hydrologic cells are used to recover hydrocarbons from carbonaceous formations. Artificial aquifers of a hydrologic cell for primary or enhanced oil recovery are constructed through the use of a conventional hydrofrac technique to make a pair of vertical extensional fractures across two parallel horizontal boreholes. Hydrocarbons move under a pressure gradient from a source aquifer to a sink aquifer. In another arrangement, artificial aquifers for exploitation of tar sands and gas hydrates are constructed through the removal of hydrocarbons which plug the pore space of the host rock. Hydrocarbons are induced to move vertically across a very large cross-sectional area from a source aquifer to a sink aquifer.

A method of propagating a fracture farther from a well-bore into an oil and/or gas-bearing zone of a target formation while inhibiting growth of the fracture into an adjacent water-bearing zone under or over the oil and/or gas-bearing zone, comprises creating a zone of increased in-situ stress a vertical distance adjacent a target interval and then creating a main fracture in the target interval by, for example, fracturing the target interval with enough fracture fluid and pressure to propagate the main fracture, inter alia, vertically to the zone of increased in-situ stress. When vertical growth of the main fracture reaches the limit set by the zone of increased stress, additional fracture fluid pumped into the target interval tends not to propagate the main fracture vertically beyond that limit and, instead, tends to propagate the main fracture more laterally and farther from the well. Such zone(s) of increased in-situ stress can be created above, below, or both above and below the target interval.

An improved method for fracturing oil wells is disclosed and claimed herein. In particular, the present invention involves the determination of the direction of fracture propagation, i.e., perpendicular to the minimum stress existing within a given formation and the alignment of perforations produced by a variety of perforating devices with the previously determined direction of fracture propagation. The methods disclosed and claimed herein will eliminate many problems encountered in the prior art, including reducing the pressure required to initiate fractures and reducing the undesirable effects of near wellbore tortuosity.