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.
