NPTS Nedra, JSC (city of Yaroslavl, the company is a part of Rosgeo state parent company) began a second drilling stage of Chumpalov 1 parametric well to a depth of 6,250 meters.

The site is located in the Prokhladnen District of the Kabardino-Balkar Republic.

The works of the first stage were completed in 2018, the well was drilled to the level of 4,850 m. The hole drilling was complicated due to the instability of the stem in the clays of the Sarmatian stage and especially the Maikop series, high permeability of rocks of the lower Maikop and chalk, which caused mud ringing and, as a consequence, the sticking of tools. Another difficulty was the drilling mud absorption in highly permeable rocks and gas water ingress in Cretaceous sediments. There were difficulties with the down casing in the process of wells reinforcement with casing columns of 508, 340 and 273 mm at small radial space in the zones of highly permeable reservoirs. The 450 ton capacity of the drilling unit allowed to perform the down casing of the mentioned casing columns in one section and successfully cement them in one stage. At present, there are no examples of similar work in the world.

A new state contract for the second stage drilling to a depth of 6,250 meters in 2018 was signed between the Department for Subsoil Use in the North Caucasian Federal District of Rosnedra and Rosgeo. It is planned to complete the project by the end of 2020.

The geologists were given the tasks to specify the geological structure of the suture zone of the Tersko-Caspian fore deep with the Nogai stage, to assess the oil-and-gas potential of the sedimentary cover deposits in the area, to obtain the geological and geophysical parameters of the exposed bore of the section in order to interpret the geophysical materials.

The filtration and capacitive properties of reservoir rocks, the nature of their saturation will be studied during the exploration, as well as the oil-and-gas generating properties of potentially oil-and-gas source thicknesses in the exposed well section will be assessed. In addition, the potential reservoir horizons will be allocated and characterized, the test objects in the casing string will be justified.

The experts will also create an array of primary data of the drilling and well exploration results, including a systematic collection of core and sludge, as well as make information and final geological reports.

In 2019, it is planned to drill a well to a depth of 5,800 m with core selection in the planned amount.

Whereas it is necessary to enter heterogeneous sediments in one stem, the drilling of Chumpalov 1 area is a complex technical challenge.

A special drilling fluid has been developed for solving these problems. It can withstand high temperatures and pressure, allowing to drill salt and gypsum depositions in the well as well as withstand the ingress of all potential contamination. This fluid has no analogues abroad and it is a unique solution developed exclusively for drilling  Chumpalov 1 site.

Source: rosgeo.com