Analyse av pumpe systemer for oppstart av brønner med lavt trykk

Abstract

Depleted reservoirs, damaged wells and high GOR ratio wells need to be estimulated in order to increase their production or to start it, normally, after wells under such circumstances have been intervened. Gas injection has been a default solution in decades for estimulating well production.

The main reason for using gas at high injection rates is to circulate the column of fluids inside the well up to the surface and reduce the differential pressure across the wellbore so that the well may eventually produce by itself.As a simple analysis, mechanical pumps do the same function, they increase the fluid rate and decrease the differential pressure so that fluids can flow easier and be transported from one point to another.

This study suggests the use of downhole Electrical Submersible Pumps and Progressive Cavity Pumps driven by electrical motors and not rods on subsea wells, in order to perform the same operation as nirogen injection. To reduce the differential pressure across the wellbore, transport the fluids from the wellbore to the surface, initially, so that the well may recover its flowing capacity.

The pumps are not to be placed permanently and are intended to be suspended by means of intervention tools (CT & WL). Intervention operations are driven currently by three different kinds of equipments, BOP, LWRP and RLWI.Results suggest the use for pumping devices above the DHSV in cases where the well has been shut in and filled with kill fluid. Such intervention can be even driven by RLWI.

However, wells with GOR ratios greater than 200 m3/m3 may represent great technical and safety challenges. Pump devices may encounter several operational problems and operations should be carried out close to the well perforations. Alternative methods should be evaluated for such case.

Analysis on pump design calculations, operational well limitations, pump capacities, well barrier schematics and intervention methodology along with disussion of the cases are further described within this project.