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Analysis

Rep Ultra Clean Tech for Low-Pressure Reservoirs

Wed, 10/14/2020 - 10:07

For decades, integrated wellbore and equipment cleanouts at production wells were done by pumping chemical products through coiled tubing using an open well hole, helped along by reservoir pressure. However, hydrocarbon exploitation has a direct impact on the loss of bottomhole reservoir pressure. This energy becomes insufficient for the fluids to circulate and therefore the cleaning of the well and the removal of deposited or encrusted material cannot be guaranteed. This leads to cleanouts that involve high quantities of nitrogen that can strongly displace the fluids toward the surface. These measures represent higher costs and lower profitability.  

When pressure in the well was insufficient to produce the necessary lift (even if great quantities of nitrogen had been injected), cleanouts were of poor quality due to the channeling of all lighter gases. As a result, fluid hung on surfaces and blocked circulation along the entire well, so more nitrogen was needed to restore circulation. This process could take up to three days and cause additional expenses.

When fluids hang, all the organic and inorganic material that a cleanout might remove precipitates and deposits on the perforation face. This means that an equipment cleanout had to be followed by a stimulation cleanout to wash those deposits away. This also generated losses in production and increases in the costs of well maintenance programs.  

The Rep Ultra Clean system is an emulsified chemical compound that acts within a broad range of temperatures and provides excellent stability and compatibility. Due to its organic origin, it does not cause any reaction that could damage the formation, or any of the materials or containers that will be intervened. Laboratory and technical tests at an industrial level reveal the efficiency of a solvent-based system for the cleaning of organic material, both at the well’s formation as well as in its ducts, containers and other equipment that enters into contact with the crude.     

With the implementation of Rep Ultra Clean technology, it is possible to eliminate organic material as well as clean all tubing of asphaltenes and paraffins. Since it is a foamed fluid, the well can continue its usual circulation while the cleanout is conducted. Thanks to the foam that is generated, the system allows for the suspension of all particles dissolved in the same fluid, which prevents their possible precipitation and accumulation on the perforation face and in the well’s general vicinity, which, in turn, prevents damage to the formations.

The amounts of nitrogen used during the circulated cleanouts and the amount of time that the well is offline and without production (or with its production deferred due to the cleanout or even to dejection) have been reduced thanks to the use of the Rep Ultra Clean system, while the inertia or constant circulation of fluids within the well insures a clean out of all tubing and perforated surfaces. At the same time, stimulations (pumping into formations) have been considerably reduced because wells can be adequately cleaned without generating precipitation, despite low pressure conditions.

Graph 1 shows interventions made in Field C. Before the use of Rep Ultra Clean, it was necessary to consider additional expenses for stimulation fluids. After using Rep Ultra Clean foamed fluid, no additional investment is needed in stimulation activities, only in equipment cleanouts.

 

Repstim is a Mexican upstream service provider focused on well interventions, stimulations, chemical cleaning and well cementing services. These include laboratory services for the analysis and breakdown of well samples.