A Case History on the Use of Down-Hole Sensors in a Field Producing from Long Horizontal/Multilateral Wells

Abstract

All of the production wells in this field were drilled and completed as horizontal and multi-lateral wells. The well designs range from a single lateral in a single sand body to where the upper and lower horizontal laterals intersect several sand lenses. The oil, an extra-heavy (9 API), high viscosity oil, requires a completion using artificial lift due to the low reservoir pressure, which will not support a column of water. The use of down-hole pressure and temperature sensors with Surface Read-Out (SRO) was an integral part of the original well completions on production wells to monitor the individual well and pump performance. Vertical monitoring wells, drilled and completed through the multiple sand lenses present, expanded the use of down-hole sensors as data was sought on the area extent and pressure drawdown in the various sands being produced. Efforts to determine the contribution to flow and the pressure losses encountered in horizontal wells led to the use of multiple sensors installed at depths along the long horizontal lateral. A change to the drilling of complex multi-lateral wells resulted in the use of tandem sensors to determine the relative contribution to flow from the lower and the upper lateral(s). All of these approaches, combined with the inability to use conventional Production Logging Tool techniques, led to the application of new technology combining fibre optics with multiple sensors to obtain a real time alternative to a PLT. As many as 15 surface read-out sensors were successfully installed in 7000 feet long horizontal well sections with measured depths up to 10,000 feet. Introduction Petrozuata C.A. is a Venezuelan joint venture company that was registered in March 1996 by Conoco Orinoco Inc. and PDVSA (Formerly Maraven S.A.), an affiliate of Petroleos de Venezuela S.A. The Joint Venture is the operator of a property in Eastern Venezuela's Orinoco belt located just East of San Diego de Cabrutica. This field development is part of a large project incorporating a pipeline network to a 120,000 bopd heavy oil upgrader facility at the coast near Barcelona. The heavy oil upgrading facilities processes approximately 120,000 barrels per calendar day of heavy oil to produce approximately 103,000 BOPD of a synthetic crude oil with a 19 to 25 API. The Joint Venture has a 35 year operating life and will require the drilling of over 500 horizontal wells that recover 1.5–2 billion barrels of extra heavy oil during that period. Construction activities commenced in January 1997. Drilling of production wells commenced in August of 1997 with "first oil" achieved in August 1998. The production wells drilling design was modified to a multi-lateral design late in 1999. The Orinoco Belt is on the southern flank of the east-west trending Eastern Venezuela structural basin and contains over 1.2 trillion barrels of oil-in-place (STOOIP). It is divided into four areas (Machete, Zuata, Hamaca and Cerro Negro). This field consists of approximately 57,000 acres (23,050 hectares) of land to be leased for the initial development of the oil field. (Figure 1) Development consists of a pad type layout. Each pad contains, initially 4 to 8 wellheads, with artificial lift pump equipment, space for drilling equipment, a flocculent pit, space for drilling trailers, electrical equipment, a multiphase meter and manifold for well testing, pipelines for crude oil and diluent, connecting to piping to/from the Main Station. The main hydrocarbon reservoirs are Miocene age sands of the Oficina Formation with average poro-perms of (35% &5,000–15,000 mD), respectively. Permeability variations are generally caused by variations in grain sizes. Sands are primarily medium grained, well-sorted unconsolidated quartz-rich sediments, with minor amounts of clay minerals. Reservoir sands consist of approximately 97% quartz, 2% clays and 1% heavy minerals.

Using Fiber-Optic-Enabled Coiled Tubing to Quantify Fluid Placement and Optimize Stimulation Effectiveness During Matrix Stimulation Treatments in Carbonate Reservoirs

“…Amongst others, DTS has been shown to enable detection of flow behind casing, cross-flow during shut-in or production, water breakthrough (Brown et al 2000), to enable the evaluation of production along multilaterals (Clancy et al 2002), or monitor fluid placement during injection Sierra et al 2008). Villesca et al (2011) summarize the four main methods used for the analysis of DTS temperature survey for injection profiling.…”

Determining Matrix Treatment Performance From Downhole Pressure And Temperature Distribution: A Model

“…In (Brown, et al, 2000), DTS is shown to enable detection of flow behind casing, cross-flow during shut-in, and water breakthrough. In (Clancy, et al, 2002), cold fluid slugs are pumped downhole and tracked along the wellbore with DTS to infer production profile along long laterals and from each lateral. In (Brown, 2006), DTS data are shown to allow the monitoring of the zones pressure and GOR when combined with a near-wellbore thermal model.…”