Multiple fracturing process

Claim 2

A process of fracturing an earth formation penetrated by a wellbore having well pipe therein comprising: perforating the well pipe along a first vertical plane with perforations having a first total diameter; perforating the well pipe along a second vertical plane with perforations having a second total diameter; injecting a fracturing fluid into the wellbore at a pressure exceeding the fracturing pressure of the preferential fracturing zone of the formation adjacent a set of perforations; and increasing the pressure on the fracturing fluid to a point where the secondarily preferential fracturing zone of the formation is fractured.

Claim 3

The process of claim 1 wherein the intersection of the first and second vertical planes form an angle of at least 45*.

Claim 4

The process of claim 1 wherein the perforations made along the first plane are positioned opposite the preferential fracturing plane of the formation and are of a smaller total diameter than the perforations made along the second vertical plane.

Claim 5

The process of claim 1 wherein the perforations along the first and second planes are of such number and size so as to restrict the amount of fracturing fluid which will pass therethrough so that the second plane of perforations will receive pressurized fracturing fluid after a fracture occurs along the preferential fracturing zone.

Claim 6

The process of claim 1 including the steps of injecting an explosive fluid into the fractured zones and detonating the explosive fluid to further fracture the formation.

Claim 7

A process of providing multiple fractures in an earth formation penetrated by a cased wellbore comprising: perforating the casing along a first substantially vertical plane with the perforations sized to restrict the amount of fluid which can be flowed therethrough; perforating the casing along a second vertical plane angled from the first vertical plane with the perforations along the second vertical plane also sized to restrict the amount of fluid which can be flowed therethrough; applying pressurized fracturing fluid to the formation through the perforated casing at a pressure exceeding the fracturing pressure of the preferential formation fracturing plane and increasing the flow rate of the fracturing fluid in excess of the amount which the perforation adjacent the preferential formation fracturing plane can take, so that there is sufficient excess pressure to fracture a second fracturing plane.

Claim 8

A process of providing multiple fractures in an earth formation penetrated by a cased wellbore comprising: perforating the casing along a first substantially vertical plane with the perforations sized to restrict the amount of fluid which can be flowed therethrough; perforating the casing along a second vertical plane angled from the first vertical plane with the perforations along the second vertical plane also sized to restrict the amount of fluid which can be flowed therethrough; applying pressurized fracturing fluid to the formation through the perforated casing at a pressure exceeding the fracturing pressure of the preferential formation fracturing plane and increasing the flow rate of the fracturing fluid in excess of the amount which the perforation adjacent the preferential formation fracturing plane can take, so that there is sufficient excess pressure to fracture a second fracturing plane.

Claim 9

The process of claim 6 including the step of determining the preferential formation fracturing plane prior to perforating the cased wellbore and aligning the perforations along the first vertical plane with such preferential fracturing plane.

Claim 10

The process of claim 6 including the steps of terminating the injection of pressurized fracturing fluid; injecting an explosive material into the fractures; and detonating the explosive material.

Claim 11

The process of claim 6 including the step of perforating along additional vertical planes prior to the step of applying a pressurized fracturing fluid.

Claim 12

The process of claim 6 wherein the perforations along the first vertical plane are located adjacent the preferential formation fracturing plane and have a lesser total diameter than those perforations along the second vertical plane.

Claim 13

The process of claim 9 wherein the intersection of the first, second, and third plane of perforations form angles of approximately 120*.

Claim 14

A process of fracturing an earth formation penetrated by a cased wellbore comprising: determining the direction of least in situ formation stress; perforating the casing along a first substantially vertical plane which is perpendicular to the least in situ formation stress; perforating the casing along a second substantially vertical plane intersecting the first plane at an angle in excess of 45*; applying a fracturing fluid against the formation at a pressure in excess of the fracturing pressure of the portion of the formation exposed by the first plane of perforations; and increasing the fracturing fluid pressure in excess of the fracturing pressuring of the remaining portion of the formation exposed by the second plane of perforations.

Claim 15

A process of fracturing an earth formation penetrated by a cased wellbore comprising: determining the direction of least in situ formation stress; perforating the casing along a first substantially vertical plane which is perpendicular to the least in situ formation stress; perforating the casing along a second substantially vertical plane intersecting the first plane at an angle in excess of 45*; applying a fracturing fluid against the formation at a pressure in excess of the fracturing pressure of the portion of the formation exposed by the first plane of perforations; and increasing the fracturing fluid pressure in excess of the fracturing pressuring of the remaining portion of the formation exposed by the second plane of perforations.

Claim 16

The process of claim 12 wherein the perforations in the first plane are smaller than the perforations of the second plane, and are of a number and size that allows only a limited amount of fracturing fluid therethrough, and the flow rate and pressure of the fracturing fluid are of a magnitude that the formation behind the second plane of perforations may be fractured after the formation behind the first plane of perforations has been fractured.