A method for hydraulically fracturing a single subterranean formation in which a fracture is first induced in the formation and then subjected to multiple hydraulic fracturing cycles to generate vertical linear fractures or to linearly extend the fracture outward from the point of introduction of the fracing fluid into a well penetrating the formation. By utilizing fracing fluid containing a high ratio of fine proppant and injected at a low rate, the linear fracturing solely within the formation can be substantially increased with very little or no radial vertical fracturing occurring outside the formation.
The use of high flash point, low vapor pressure compositions for injection into, and coating of, gas and oil wells and surrounding underground hydrocarbon bearing formations and processing equipment for the purpose of removing scale, paraffins, tars, and other viscous constituents. Treatment results in increased flow of gas and/or oil and decreased adhesion of soil and scale in all aspects of oil and gas recovery, including hydrocarbon bearing formations, casings, lines and pumping equipment. The composition contains about 40 to 99 wt. % of a fatty acid alkyl ester blend and about 1 to 25 wt. % of at least one lower alkyl glycol ether.
In the preferred embodiment of the present invention, completion operations are performed which include a perforation operation followed by a fracturing operation. During the perforation operation perforations (or other means for creating flow paths) are shot at a low perforation density, in order to create a flowpath between the wellbore and the hydrocarbon bearing formation as well as an unknown number of relatively wide fractures and relatively few, but unknown number of fracture initiation sites in the hydrocarbon bearing formation. During the fracturing operations, relatively small, high-concentration proppant slugs with clean spacer stages are pumped early in the treatment, in order to screenout the narrower fractures, but these slugs are not sufficient to screenout the wider fractures. Next, conventional fracturing operations are employed to create and/or enlarge and widen the remaining wider fractures, without the risk of loss of relatively-expensive carrier fluids and proppant material (such as sand) to the now-screened-out smaller fractures. Experimentation has revealed that this technique can be employed to (1) likely create longer and wider fractures, and (2) increase the overall sand-to-fluid ratios.
This invention pertains to a novel method of fracturing subterranean coal formations as a means for stimulating the production of coalbed methane. A highly conductive proppant pack is emplaced in the fracture during the fracturing treatment that has a particle size gradient ranging from about 40/70 mesh at the leading tip of the fracture to about 12/20 mesh at the trailing base of the fracture. The fracturing process is conventional in the sense that the materials and equipment used in the process are well known. The manner in which such materials and equipment are used to fracture coal degasification wells is new.
A method for controlling the vertical growth of hydraulic fractures in subterranean formations. The fracturing gradients of adjacent formations are determined. The fluid density necessary to inhibit the propagation of a hydraulic fracture from one adjacent formation into the other is determined from the fracturing gradients. A fracturing fluid is prepared having the necessary density for inhibiting such hydraulic fracture propagation.
During fracture treatment of a subterranean formation, multiple hydraulic fracturing cycles are performed wherein the bottomhole treating pressure of a wellbore is controlled to not exceed a maximum bottomhole treating pressure for the formation, thereby attaining maximum principle fracture extension and limiting initiation of secondary fractures transverse to the principle fracture extension.
