Fracturamiento hidraulico

The Study of a New Concept of Low-Damage Fracturing Technology in Low- Permeability Exploration Wells

Abstract
In low permeable exploration wells, how to minimize formation damage and fracture damage is regarded as an unique goal of hydraulic fracturing design and treatment. Sometimes, an inappropriate fracturing design may even decrease an exploration well’s oil production potential as aresult of high damage within both formation and fracture, so that an error decision-making may be determined. Therefore, a new fracturing technology of low damage for exploration wells is put forward in the paper, compared with the past conventional fracturing technology, the highlights of the new technology
includes: 1) A new concept of damage is established anddemonstrated, it contains not only damage as just mentioned above but also excessive fracture height growth, inappropriate proppant propped pattern and so on; 2) utilizing the newly developed fracturing fluids such as slick water, low concentration of densifier, linear gel (not cross linked), low molecular weight fluid, etc.; 3)optimizing the minimum viscosity of fracturingfluid, then optimizing the corresponding
pumping rate; 4)studying the optimum combination of fracturing fluid types and that of proppant type and size in the course of fracturing treatment; 5)Studying the sensitivity of formation damage and fracture damage to the post-fracturing performance, which may be used to select fracturing treatment parameters inversely; 6) one of the mainoptimization target is to minimize fracture propagation length after shut-in so as to obtain an optimized propped profile; 7)studying the mechanism of water blockage during the course of fracturing treatment and the countermeasures correspondingly. What’s more, above fracturing technology has been put in to field applications and an expected result has also been obtained, so it has a greatsignificance in improving fracturing technology, reservoir evaluation and reservoir development as well.
Introduction
It is well known that hydraulic fracturing technology has been
playing a more and more important role in low permeable oil and gas bearing reservoirs’ exploration and development as well. However, an inappropriate fracturing design and treatment may even worse the situation withmisunderstand the reservoir quality in exploration zones or decreasing post-fracturing production rate in oil and gas bearing reservoirs being put in to development. What emphasizes here is how to optimize hydraulic fracturing design and treatment in exploration wells. As we all know that it is very sensitive to foreign fluid in low permeable reservoirs, so, low damage fracturingfluids such as slick water, linear gel (not cross-linked), low polymer concentration cross-linked gel and low molecular weight fracturing fluid as well are often utilized. However, this is only one aspect of the problem concerning with damage. In our study, a broader concept of damage is established which includes not only matrix damage and fracture damage in normal sense, but also excessivefracture height growth, unfitted propped length with well pattern and well space, inappropriate proppant propped profile, continuous fracture propagation after shut-in, higher viscosity and pad volume of fracturing fluid than actual need, incompatible fracturing fluid with that of formation, inadaptable combination of fracturing treatment parameters and so on.
However, when a hydraulicfracturing design is performed, an equal emphasis should be put on both the ensure of fracturing treatment success and satisfied post-fracturing performance. It is well known that higher viscosity, redundant pad volume and higher pumping rate as well may ensure the success of a fracturing treatment, but the post-fracturing effect may be decreased in a larger degree correspondingly. On the other hand, a...