Keep Calm and Carry on: How Dynamic Modelling and Optimisation has Helped to Maintain Production across the Azeri-Chirag-Guneshli Field

Abstract

The Azeri-Chirag-Guneshli (ACG) field is a giant oil development located in the Azerbaijan Sector of the Caspian Sea. The presence of multiple layers and a secondary gas cap has seeded a range of transient phenomena that includes well slugging, cross flow and gas coning. Dynamic transients seen across the field have contributed to a detrimental impact on production. Well slugging has led to the failure of downhole screens and decreased production. The cross-flow of water between the different reservoir layers is another problem that can increase the water cut by 30% during start up, making it extremely difficult to return a well to production. The gas to oil ratio (GOR) remains very dynamic. When shut in, gas will migrate away from the well bore leaving little free gas to lift the oil. Similarly, the GOR will rise during periods of production as gas is coned into the well. As a result production can be backed out. Underpinned by extensive dynamic modelling work, BP, together with its Partners and the State Oil Company of the Azerbaijan Republic, has been successful in deploying technology to assist in stabilising and enhancing production across the ACG field. Well uptime has been improved by optimising the dynamic transients during start-up. Conditioning the well before it is shut in has proved effective at reducing the cross-flow of water that occurs immediately afterwards. In this paper, the challenge of optimising the dynamic transients across the ACG field will be discussed. Particular emphasis will be given to the solutions developed to address the underlying transient phenomena and how these solutions were deployed at scale and pace across the field.