CLOV Project: Overview

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 25789, “CLOV Project: Overview,” by Geneviève Mouillerat, Total, and Francisca Silva, Sonangol, prepared for the 2015 Offshore Technology Conference, Houston, 4–7 May. The paper has not been peer reviewed. This paper describes the CLOV deepwater megaproject in Block 17 offshore Angola. This major development encompasses four separate oil and gas accumulations in waters up to 1400 m and aims to recover 505 million bbl of both light and heavier oil plus associated gas in quantity sufficient to require an export solution to shore for inclusion in the Angola liquefied-natural- gas (LNG) project. Introduction The CLOV megaproject of USD 8.4 billion (to first oil) in Block 17 offshore Angola is the fourth in a series of deepwater developments. The cluster of fields that gives the megaproject its name—Cravo, Lirio, Orquidea, and Violeta—is 140 km off the coast of Angola and is west/northwest from the earlier developments at Girassol, Dalia, and Pazflor in waters ranging in depth from 1100 to 1400 m (Fig. 1). CLOV came on stream on 12 June 2014 and reached its production plateau 3 months later. The four fields have recoverable reserves expected to be produced over a 20-year period. The oil is a mixture of good-quality light Oligocene crude (75% of recoverable reserves) and lower-quality Miocene crude. The presence of the latter has had a material effect on the development scenario for the complex. Exploration Development The complex of fields was first discovered in the summer of 1998 when the Lirio-1 well was drilled, finding a significant Oligocene accumulation with a large gas cap. The oil-bearing reservoirs in the northeast compartment of the structure were confirmed by the Lirio-2 appraisal well, which also further delineated the size and extent of the gas cap. The following year, Cravo-1 confirmed further light-oil reserves before the first appearance of the heavier Miocene oil at Orquidea-1. Additional exploration wells further revealed the complicated nature of the reservoirs at the location. Violeta-1 added to the Miocene reserves, but the Orquidea-1 well, drilled into a deeper horizon and 15 to 20° downdip of the main reservoir, revealed more light oil, which would provide an additional challenge at the well-design stage as a result of difficulty in defining well objectives. Subsurface work continued, and revised reservoir models indicated that the reserves for Cravo-Lirio would exceed the 245 million bbl given by an earlier estimate. The question remained whether the reserves warranted a standalone development. The first conceptual studies for these accumulations were carried out in spring 2005 to give some definition to subsea architecture, topside design, and a central facility. After the Lirio-2 appraisal well (drilled later that year) increased reserves, preproject studies were launched on the assumption that Cravo-Lirio would constitute a standalone hub with a floating production, storage, and offloading (FPSO) vessel, with the Miocene finds as a later tieback. A year later, following additional integrated geological and geophysical studies of the Miocene finds, which included data from two more appraisal wells (Orquidea-2 and Violeta-2), it was decided to choose a development concept that incorporated the Oligocene and Miocene accumulations.