RIASSUNTO
Abstract
Exploration well testing in an environmentally sensitive offshore area presents technical and economic challenges to the oil and gas industry. This paper presents the approach recently taken in the La Vela Costa Afuera concession, an offshore block in an environmentally sensitive area, located off the northeastern coast of Falcon State in Venezuela. Given the very strict guidelines enforced by the Venezuelan environmental authorities, and the waxy nature of the crude expected, the initial choice at planning stage was to opt for a zero-liquid flaring solution. This meant mobilizing a floating production storage and off-loading (FPSO) system or a rig supported crude stabilization process and a suitable transport vessel. There was also the Venezuelan Ministry of Energy and Mines (MEM) desire not to waste the commercial value of Hydrocarbons.
Such solutions imply substantial operating costs, in particular with respect to the short duration of the exploratory well-testing activities. These costs justified investigating alternate, more cost-effective solutions that would also meet the environmental requirements.
An environmental impact study was conducted by an independent consultant that included an evaluation of fallout from oil flaring, impacts of emissions and heat radiation. Inputs from the operator, the local environmental authorities and the well-test oil burner manufacturer were used to evaluate the environmental effect of burning the waxy crude oil.
The study covered health, safety and environment (HSE) considerations such as hazard identification, pollutant dispersion study, oil-spill contingency plans, and rig and personnel safety.
The results were presented to the Venezuelan authorities, and permission to flare was granted by the Ministry of Environment, Ministry of Energy and Mines and the national oil company Petroleos de Venezuela S.A. (PDVSA).
Oil with a 35 to 40°C pour point, 33°API gravity and containing as much as 35 to 40% paraffin was successfully flared using a new well-test oil burner. Thorough observation confirmed that no oil fallout occurred during the continuous flaring operations, some of which lasted up to 23 hrs.
Careful analysis of the risks, use of the latest flaring technology, and early coordination with the environmental and other governing authorities demonstrated that even the most stringent environmental requirements can be met without incurring high operating costs.
Well-testing fluid disposal using latest flaring technology can be a viable, cost effective, and environmentally sound solution.
Introduction and Background
Phillips Petroleum Venezuela LLC is the operator of the La Vela Costa Afuera concession, an offshore block in an environmentally sensitive area along the Venezuelan Coast. Participants in this offshore concession included Atlantic Richfield Company, Fletcher Challenge and Exploracion y Produccion Inversion Colectivia, S.A.
Geographically the La Vela Offshore Block is located in the Northeastern Coast of the Falcon State, between La Vela de Coro and Puerto Cumarebo, and East of the Paraguana Peninsula where the Los Medanos de Coro National Park is located (Fig. 1). The area has very little oil tradition and is mostly known for its fishing potential, which is the main commercial activity practiced by local fishermen.
The block covers an area of 3800 km.2 The Venezuelan Ministry of Environment excluded two zones from exploratory drilling mainly to protect coastal areas and ecologically sensitive systems both on land and offshore.
This paper presents the preparation and execution of well-testing activities conducted on two exploratory wells, LVC-28X and LVC-29X, located respectively 8 km and 19 km north of the nearest northern Venezuelan coastline.
Testing for Exploratory Well LVC-29X, was conducted during the monh of February 1999 and during the month of May 1999 for Exploratory Well LVC-28X.