GEOSYNTHESIS ENGINEERING

Development and service of drilling fluid

It’s interesting

«Mente et malleo»

Work on Machehskaya area was commenced in 1991-1992. By that time, after another reorganization of PA UkrNIGRI (Ukrainian Scientific and Research Institute of Geological Prospecting) A. Rozengaft’s lab was merged with I. Khariv’s lab. This conglomerate proudly received the following name: Laboratory of drilling-in, testing of formations and physics-and-chemistry of drilling muds. There were not many questions regarding muds, whereas testing became an issue…

By this time “Poltavneftegazgeologia” faced a problem with well testing on Machehskaya area. We were the ones assigned to solve it. And the problem was this.

At the area with the debit of around 150 000 m3/day well №500 was in operation. It was an exploratory well which discovered the field. It did not bring too many complications. Two more wells were sunk. They were drilled with mud density of 1960 kg/m3. After the casing was inserted it was perforated using hydraulic jet perforation and the development started. This development took place with mud replacement with water. And this is when it all started. Vigorous gas stream and rush of a great amount of the cuttings, argillites mainly.

This was or the other well №1 died pretty fast. The casing was smashed but attempt to kill the well was successful. With well №2 the situation was even more interesting. The cuttings clogged the tubing string. Of course, the well was killed but during the following year and a half blowout response service was working hard to pull the tubing out of the well and drilled pipes. In the pipes, under plugs formed by cuttings there were accumulations of gas under high pressure.

You can read how we solve this problem in 1993 during further well testing in the article: “Peculiarities of testing unstable crumbling reservoirs with abnormally high formation pressure”. It is available from our website. It was a gorgeous victory. Several days after well testing L. Kravchuk (then the President of Ukraine) gives a speech on TV: “I have just been informed that in Poltava region we received a powerful gas inflow in one of the wells…”. This was about Machehi.

The technology that we elaborated allowed not only to prevent rock collapse but also to produce with the debit of 1,67 mln. m3/day from a crumbling deformable reservoir. We even applied for a State Prize which we did not receive, though. But on the other hand a reporter came to the Institute to make coverage. We were published in the newspaper article under the title “A present for the jubilee” accompanied by a photograph. But, again, a brick was dropped – Yu. Luban and G. Vinogradov were wrongly signed in that photograph.

All this happened exactly 20 years ago.

The work on well №79 Valyuhovskaya was commenced on March 26, 1997. This was the third well given to SPE “Zond” for mud servicing.

These were “dark” 90s when the majority of the wells were stopped due to the lack of chemicals. As a rule, these wells were stopped when there was no even slightest ability to drill further. Either the accidents were to blame, or the boreholes were in a very complicated condition.

Nobody already remembers what happened to this particular well but definitely there was some situation as we received it after a shutdown, with the bottomhole at 4647m. Ivan Khariv dealt that well directly. The works were usual. PP-2C agent was prepared. A transition from one mud type to the other was designed and tested in the laboratory. The mud was treated at the well. PIBR-2 system was obtained as a result. All the problems were eliminated rather quickly, drilling up to 5550m was performed and it was successfully forgotten.

And suddenly! In 2013 well-control equipment registered gas leakage in the well. Moreover, the pressure is more than 150 atm. Imagine that, it is still working!