Development patterns and key techniques of coal-formed Kela 2 gas field

Kela 2 gas field in Tarim Basin is a rare large-scale full-contained, superpressured dry gas field in the world, and its development is extremely complicated. After detailed technological research breakthrough, the development concept of drilling few high-production-rate wells is formed, that is, the main producing wells use 177.8 mm (7 in) diameter tubing in order to make full use of the formation energy. The fine 3D geological model of huge thick sandstone reservoirs is built constrained by the lateral reservoir prediction data, sedimentary facies data, and so on. And the development mechanism of the superpressured gas reservoirs has been studied based on this model. The rock deformation effect must be included in the deliverability evaluation. A material balance equation for superpressured gas reservoirs with aquifer drive is derived for the dynamic reserves calculation, and the reserves derived from the conventional pressure drawdown method is 1.5 to 2.1 times the actual dynamic reserves. A temperature correction method is formed to solve the decline of the wellhead pressure build-up curves of superpressured gas wells at the later stage, and this method is verified to be credible.