The use of hydrajetting for perforating of wells has been commonplace since the 1960s. During those early years, wells were relatively shallow, and jetting success was consistently demonstrated. However, as wells became deeper, where rock formations tend to be harder, hydrajetting performance became less dependable; subsequently, stimulation failures more often occur as a result of the lack of fracture initiation. To remedy this situation, a series of tests were performed to define new best practices for hydrajet perforating of hard rock under high ambient pressure environments. Various rocks were subjected to these tests, which were performed using different jetting pressures and different abrasives. The perforation surfaces were then dissected and evaluated using photographic and chemical means. Further assessments were then made to determine what actually occurred during the hydrajetting process. This paper discusses various test results, and new constraints for hydrajetting are defined and presented.

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractThe objective of this paper is to summarize the future application, limitations, advantages and disadvantages of UBD technology, based on eleven wells that were drilled in this type of reservoir. The geographic location of the wells is the Center of the Neuquen Basin, located in the state of Neuquen, Argentina. The objective was to define the reliable range of the stratum flow capacity value or permeability, in order to forecast the reservour productivity with UBD Technology, assuming the absence of formation damage (skin). The method used was based on the transient-state production equation theory. Implementation was based on the drilling hydraulics design: maintaining constant Pwd close to the reservoir of interest formation pressure; stopping drilling to allow the development of transient production; establishing drilling conditions and detecting the production contributions in new stratums to be evaluated; determining the average production; correlating detected inflows with the pressures obtained by formation testing. The method, together with other data, allowed us to estimate the structure potential productivity, despite the poor petrophisycs characteristics (Tight gas reservoirs) and to demonstrate that the results during completion could give reliabie properties estimatations used in the forecast.