Recognition,distribution and genesis of the water-rich strata in the Jingbian Gas Field

The Mawu gas pool within the Jingbian Gas Field lies in the central part of the Ordos Basin. The integration of genesis, evolution and distribution shows that no well-defined gas-water interface has been observed in the Mawu gas pool. The "relative water-rich areas" appear as masses or lenses chiefly in the western part of the gas field, characteristic of the co-existence of gas beds and water beds. The existing formation water in the Mawu-1 stratal pores is believed to be the bound water preserved in the pores during the migration of natural gas, or the relict flowing water due to the deficiency of gas energy. Reservoir variations and the formation of local dense zones in some parts or well areas permit the preservation of abundant formation water and thus the formation of the "relative water-rich areas". Although the water production in the course of gas pool exploitation tends to be related to the regional distribution of the "relative water-rich areas", it only has limited effects on the overall development of the gas pool in the study area.