Development of Fields with Complex Environmental History Key Engineering and Technological Solutions
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AbstractThis paper is dedicated to the key engineering solutions concerning development of the Kumzhinskoye field. The focus is put on the field development principles related to its complex environmental history.The challenge we face in this field results from an accident that occurred while drilling well 9 in the crest of the structure due to failure to meet regulations on integrated gas and gas-condensate well testing procedures with regard to well production rates through orifices of certain size and duration of well production at those rates. Abnormally high gas flow rates amounted to 807 thousand m3 per day. The problem and severe pollution near the well resulted from a nuclear explosion 1500 m deep aimed at shearing the wellbore due to displacement of a rock mass. However, instead of the accident remediation the explosion increased the area of gas and condensate blowouts. As a result, a huge damage was inflicted to the environment and the Pechora river delta ecosystems. Exploratory wells are exposed to aggressive hydrogen-sulfur medium. Poor cementing creates the conditions for gas crossflows from natural reservoirs to overlying water bearing zones forming human-induced gas deposits. Accident remediation took almost 15 years.It is important to realize that environmental challenges of this field are so huge that it is useless to handle them from the surface. Solution of environmental problems requires an integrated approach to the field development.First, the primary reservoir is to be depleted to make its pressure drop below the pressure in the secondary induced deposits (200 Atm) and shut down the upward gas migration. Second, shallow slim holes are to be used to deplete induced deposits. To minimize the environmental damage, we are planning to ensure complete gas recovery using only 18 horizontal wells. We shall drill those wells from only 2 well pads minimizing land allotment for industrial purposes. In addition, these well pads are located in dry elevated areas outside the national reserve territory.
