Unexpected Near-Critical Reservoir Fluid Behavior in the North Monagas Oil Province, Venezuela

Abstract

Corpoven, S. A. an operating Affiliate of Petroleos de Venezuela, S. A. has recently Petroleos de Venezuela, S. A. has recently commenced production from a newly developed oil province located in the northern sector of the province located in the northern sector of the state of Monagas, eastern Venezuela. Simulation of well stream phase behavior and production fluid pressure vs. temperature production fluid pressure vs. temperature traverses in the CARITO 1-X well have indicated that some horizons defined as gas condensates produce fluids to the surface via the normal produce fluids to the surface via the normal condensation process, while other sands also defined as condensates produce to the surface as a light oil or quasi-critical hydrocarbon liquid. Numerical evaluations have shown that the latter case occur at certain fluid transport rates via a progressive transition of the gas from the dense phase to the single phase liquid region. This flow responds to the flowing pressure vs. temperature relationship in the pressure vs. temperature relationship in the wellbore above the critical pressure and temperature of the fluid. The identification and description of this anomalous behavior is very important to Corpoven's North Monagas operations because it allows for proper identification of CONDENSATE GAS RESERVOIR production. This classification receives special OPEC consideration under existing technical definitions. This paper deals with the reservoir fluid characterization procedures, simulation techniques, and phase procedures, simulation techniques, and phase equilibrium considerations required to properly identify the producing horizons in the CARITO-1X well. Introduction The CARITO 1X well belonging to the "New Areas of Northern Monagas, field was drilled during September 1987. The final objective of this well was the Caratas Formation, a Cretaceous accumulation at 13000 ft (3963 m). The well reached a TD of 15000 ft (4573 m) and was successfully completed in November 1987. The following stratigraphic column was clearly identified in the well:CARAPITANARICUAL SUPERIORNARICUAL INFERIORLOS JABILLOS The sands pertain to the Oligocene, Eocene, and Cretaceous sands of the CARITO field, and border the CARITO WEST field to the West, along with the FURRIAL-MUSIPAN field to the East. The well produced some 4805 BOPD (7654 M3/D) of 31.1 degrees produced some 4805 BOPD (7654 M3/D) of 31.1 degrees API condensate at a total GLR of 3891 SCF/STB (691 SCM/M3). The fluid from the well corresponds to the NARICUAL SUPERIOR Sand. Five (5) horizons were sampled in the well in order to identify and characterize the original fluids in the laboratory. Chromatographic analysis of the hydrocarbon content through Eicosanes + (C1-C20+), and NSO) compounds yielded a strong paraffinic fluid with a Watson Factor (Kw), of approximately 12.5 Initial reservoir conditions are given by Table 1. Each one of these intervals was represented by a proper PVT study in accordance with the proper PVT study in accordance with the condensate or quasi-critical nature of the reservoir fluid. For the first four (4) condensate sands shown in Table 1 the reservoir study was comprised of four basic procedures as follows:Fluid Analysis: Liquid/gas recombinationRelative volume vs. pressure at reservoir temperature determination. P. 301