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Non-damaging Killing of Wells for Maintenance And Repair Works

It is impossible to perform high quality repair and maintenance works in wells without killing of the wells. Multiple well killing with aqueous fluid affects negatively the reservoir properties of formation pay zone. To preserve reservoir properties some modifying additives are added to the brines, which provide brine compatibility with formation fluids, reduce oil-water interfacial tension and change rock wettability, reduce the residual water saturation of reservoir and increase relative oil permeability ratio.

Well killing, even within the same area, requires an individual approach to the selection of killing fluid param-eters. The use of specialized solid-free killing fluids can reduce significantly the period of bringing of wells to stable production after repair and maintenance operations, as well as increase significantly oil flow rates.

In some cases, compatibility of killing fluids and formation fluids can only be achieved with the application of calcium-free killing fluids.

Technologies and chemicals for non-damaging killing of wells for maintenance and repair works:

1.     Non-damaging killing of the wells with abnormally high formation pressure:

     -     High density brines of TZhG brand with the densities ranging from 1.3 g/cm3 to 2.25 g/cm3;

     -     Dry compositions of TZhS brand for making of high density brines for killing of wells.

2.     Killing of the wells with abnormally low formation pressure:

     -     Water-based ultralight killing fluids of ULZhG brand with the densities ranging from 0.7 g/cm3 to 0.99 g/cm3;

     -     Hydrocarbon-based ultralight killing fluids of ULZhG brand with the densities ranging from 0.53 g/cm3;

     -     Hydrocarbon emulsions based on emulsifiers EKS-EM® and EMITRIT®.

3.     Modifiying of well killing brines and process fluids, displacement fluids, flushing or circulating fluids with hydrophobic surfactant chemical GF-1.

4.     Fluid loss control at well killing operations at maintenance and repair works in the wells with Abnormally Low Formation Pressure (ALFP) with high formation permeability with with the help of temporary blocking pack PLASTIROX®.

5.     Reducing of H2S and mercaptans content in killing fluids and in flushing or circulating fluids when performing the works in the wells complicated with the presence of H2S and mercaptans with the help of H2S scavengers of PS brand.

6.     Preventing of scale precipitation with the help of scale inhibitors of SALTONIX and INIPOL®32 K brands.