Complex Technological Solutions to Isolate Intervals of the Acquisitions Process Fluids
Authors: Yuriy Ugol'nikov 
Published: October 2016

The problem is the wiring of the borehole in the intervals of highly permeable sediments, prone to absorption in various mining and geological conditions is described repeatedly. It is well known that absorptions are the most expensive (in relation to materials and time) kind of complications when posting wellbore. In some geological regions this is a major problem; and that significantly affects the important parameters for the implementation of drilling operations. To the detriment of the basic principles of design ineffective design changes of the well can be conducted.

The causes of absorption, as well as the geological structure of complicated intervals, are individual in each case. The common and major cause of absorption is the excess hydrostatic pressure of the column of borehole fluid above the formation or pore pressure of the absorbing horizon. This statement is true not for all the fields, as even with a decrease of hydrostatic pressure the integrity of the wellbore required to continue drilling may be recovered only in rare cases.

In most cases the absorption is conditioned by the presence of high permeable intervals where defects of rocks represent a network of pores or cracks having a hydrodynamic connection. In some cases, some of these defects can be filled with a material prone to rapid dissolution or suffusion. The absorption in these intervals is, as a rule, the avalanche-like character with increasing intensity, in the case of inadequate technological solutions.

Today, there are many methods, technologies and materials, which showed high performance in specific geological conditions, but which are not absolute panacea, which confirms the structural and textural uniqueness of the most absorbing intervals. In most cases, the use of only one material or method of insulation creates the prerequisites for positive dynamics however the achievement of desired results (even after multiple repetition of the same technology) is carried out in exceptional cases. This is because each particular material or technology is aimed only at a particular aspect of absorption: this may be a decrease in the rate of drainage, the reduction of the channel cross section of defects of the rock, or the restoration of the geometry of the wellbore. To influence all aspects at once, using only one technology would not be possible.

While performing insulation works in wells in different geological regions, the specialists of our company has seen that the process of isolating the intensive absorptions is to be implemented in stages, comprehensively. In this case, each previous stage is preparatory for the next. The relative duration of the insulation process is balanced out by its effectiveness and lack of recurrence of complications at further technological operations during the posting of the wellbore.

Studying both positive and negative experiences, including advanced technologies in the field of insulation intervals of absorption, there are several basic stages of process of liquidation of absorption of processed liquids. The proposed classification is not absolute for all cases of absorption, but only performs the function of framework, algorithm, when selecting materials, tools, technologies of insulation works.