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.
In this study, the historical production of VacaMuertais evaluated aiming to capture the complexities of this formation in terms of fluids production and recovery performance. This paper integrates the Neuquén province production analysis with the objective to understand the oil and gas historical production behavior in a development area of roughly 12,000 sq mi (31,000 km2).A comprehensive evaluation using public data was conducted to present the contribution and the impact of VacaMuerta oil and gas production on the region and the country. The VacaMuerta formation represents the most-challenging source of new oil and gas in Argentina, with a huge potential considering the size of the development area in any block across the basin, the reservoir gross thickness and the resulting fluids in place, and the way forward to be achieved regarding the balance between well cost reduction and productivity improvement. There have been important drilling and development efforts in the last 4 years in which both vertical and horizontal wellbore configurations have been implementedand tested over the longterm. However, there are still uncertain factors under evaluation to assess the VacaMuerta formation performance, which achieved 29 million barrels and 124Bcf in December 2016, with 674 oil and gas producer wells. The workflow focuses on the analysis of historical production for both vertical and horizontal wells, average rates and cumulative production of initial 6 and 12 months, water cut and gas-oil ratio (GOR), decline analysis and vintage performance, with the addition of heterogeneity index plots. Production history statistics and probabilistic analysis were incorporated in the study to summarize and present the evaluation results. Important aspects related to well decline behavior and estimated recovery for the initial years were also analyzed. In this paper, we present the main findings and results of a complete production analysis of VacaMuerta formation after more than 10 years of production. This paper provides an overview of the historical production performance and the key elements for production forecasting. The integration of this production information with geology, reservoir characterization, well design, and completion and operation strategies provides an essential reference to improve the understanding of the production potential and the visualization and ranking of any well, field, or area in the Neuquén basin.
In the continuous search of the optimization of investmensts and the reduction of operative costs, Repsol-YPF decided to research the possibility of the use of Coiled Tubing to produce traditional diameter wells at the Golfo San Jorge Basin. This represents a further step after an experience undertaken in reduced diameters started in 19971. Through this new experience it was proven that it is posible to produce wells with diameters higher than 3.5 in. Using coiled tubing in mechanical pumping, generating at the same time new possiblilities for coiled tubing with other artificial lift systems. Introduction Both already drilled wells as well as new projects at the San Jorge Basin have characteristics that make them overly sensitive to the oil price and to the cost of materials and services used for their construction and exploitation. It is due to this fact that the operating companies are permanently involved in the research of new possibilities to improve the profitability of the fields. The installation of 5900 ft of coiled tubing in two wells 2266 ft and 2715 ft deep respectively is one of the experiences carried out to pursue that end. Most of the wells have depths that range between 1640 ft and 7216 ft and produce from several fluvial reservoirs at the same time. The characteristics of the produced fluids, such as WOR, GOR, and viscosity, vary according to the zone, but, as a rule, the fluid produced is a three-part mixture (gas, water, and oil), to which variable quantities of formation sand are added. The oil and gas have in turn various constituents that in some cases originate the settling of paraffines, asphaltenes, carbonates, etc.. These characteristics generate the need of frequent interventions with hot oil or workover rigs. The main artificial lift systems are the mechanical pumping and the progressive cavity pumping (PCP), being the latter one chosen more and more often. Although the ESP pumping (electro submersible pumping) is less frequently used, it will gradually have more participation as the waterflooding projects continue to prosper. The coiled tubing designs installed show that even under the difficult production conditions previously outlined it is posible, although with some limitations, to produce the oil wells replacing the tubing and sucker rods in some cases. The possibility of replacing the sucker rods in wells with high operative costs due to frequent failures in mechanical and PCP pumping is also foreseen. Replacement of tubing and sucker rods. The main advantage of installing coiled tubing is the replacement of 2.875 in. tubing and 1, 0.75 and 0.62 sucker rods normally used in 5.5 in. casing wells. Thus, the coiled tubing should transmit the alternative movement (upward and downward) to the downhole pump, and also conduct the produced fluid to the surface. All the elements used are common in mechanical pumping and coiled tubing works, or have slight modifications.(Fig. 1). Since there are no experiences of this kind of such a system, the resort used was a specially designed software, in order to determine the working life of the installation of the coiled tubing and to observe how the geometrical and operative parameters affect it. The afore mentioned software is a simplified mathematical model and does not take into account the forces generated by friction, viscous friction, flotation or pumping pressure. There are no studies or experiences that take into account the coiled tubing fatigue under the conditions outlined above. There are only experimental works on low cycle fatigue that had been performed by coiled tubing manufacturers and by companies that use it to service wells2, jobs in which the main fatigue effect is the continuous bending and straightening on the reel, gooseneck and injector head. Therefore the life estimated by the software should be taken as a first approximation and, above all, as an exercise that allows for the observation of the interdependance of the different geometrical and operative parameters.
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