DESIGNS OF OIL-AND-GAS WELLS AND THEIR INFLUENCE ON THE DRILLING RESULTS

The definition of the term “well” is provided in the article. The design of an oil-and-gas well in the Transcarpathian depressionis given as an example; the article contains explanations on which casing strings should be sunk, for what reason and how deep it should be done in order to get a positive result. This article demonstrates a scheme of equipping oil-and-gas wellheads with Christmas trees. Essential designs of project wells that ensure high-quality drilling resultsunder different geological conditions are shown in the article’s second part. The wells’ design on the territory of deposits with simple geological structure may be unsophisticated and include a conductor casing at a shallow depth and a flow string before overlaying of a payout bed. The deposits overlaid by sediments not during drilling require high density of drilling fluid; those sediments should be overlaid by a liner and continue to be drilled till payout beds and using fluids with low density. Multiple casing string designs are used under complex geological conditions and in case of extremely deep wells.