Asphaltene Cleanout Using VibraBlaster Tool

Abstract

Abstract Remediation of heavy organic deposits of asphaltene in the course of oil production has been a costly process and it has hampered the production activities. Well 1 was initially put in production on December 14, 2005, but it failed to flow against the flow line pressure of 260 psig and later against a reduced HPTT pressure of 50 psig. Heavy asphaltene emulsion solids were found to be completely obstructing the tubing, which could not be subsequently displaced or cleaned out by bullheading either water or Xylene. To break up the asphaltene and restore the productivity of Well 1, the following options were considered: bullheading water, xylene wash, rotating nozzle CT, workover and using the VibraBlaster™ tool. In January 2006, water bullheading was first attempted with no success. In March 2006, xylene wash was attempted, again with no success. In August 2006, the VibraBlaster™ tool was deployed with coil tubing and attempted to remove the emulsions using the tool's vibration and reciprocation, combined with its high velocity jetting. The VibraBlaster™ tool succeeded in breaking up the solid asphaltene accumulations on the Christmas tree and the first 1900' of tubing, restoring the well's production with a current oil rate of 10.7 MBOD and 0% water cut at 26/64" choke setting. Close subsequent observation of the well confirms that it is behaving like a normal GOR well, while crude samples also indicated normal levels of asphaltene (2–3%). Reservoir Description The limestone carbonate reservoir is one of the major associated gas oil reservoirs in the giant Ghawar Field in eastern Saudi Arabia. The limestone formation is subdivided into five depositional layers, named Arab-D Zone-2A, 2B, 3A, 3B and Arab-D. Table 1 displays reservoir properties of limestone carbonate reservoir. Introduction Asphaltene is defined by chemists as the part precipitated by addition of low-boiling paraffin solvent such as normal-pentane and benzene soluble fraction whether it is derived from carbonaceous sources such as petroleum or oil shale [5–1]. Asphaltene precipitation and deposition in oil production systems depend on the changes in the flow conditions such as pressure, temperature and oil composition [1–1]. The main factor that plys a major role in asphaltene problems under flow conditions is the well flowing pressure behavior. Well 1 is a single lateral Arab-D horizontal oil producer completed with Pressure Down hole Monitoring System (PDHMS) and M-Pass packers in October 2005. Asphaltene precipitation in the upper 1900'of tubing caused a complete flow restriction regime. It was one of a number of wells in the area that experience asphaltene precipitation. The other nine wells precipitate asphaltene in the rat hole below the pay zone for having free gases, high gas oil ratios and high flowing wellhead pressures. Those wells induced equilibrium between asphaltene precipitation below pay zone and production, which by gravity lifted asphaltene to the surface. Well 1 was not expected to produce asphaltene from a PVT perspective because it did not have free gas and high gas oil ratios. Pay zone and production, which by gravity lifted asphaltene to the surface. Well 1 was not expected to produce asphaltene from a PVT perspective because it did not have free gas and high gas oil ratios.