Tracer testing

Goals and objectives:

• true velocity and filtration direction of reservoir fluids and injected water;
• heterogeneous sediments, reservoir properties under conditions of natural occurrence
• horizontal and vertical well-to-well connectivity, flow distribution in reservoirs and between individual wells
• oil and gas displacement process efficiency, its dependence on individual wells, conditions of reservoir draining and injection
• sources of water troubles

The results:

• development / sustainable further;
• recommendations for system optimisation of reservoir pressure maintenance
• assessment of carried out and planning forthcoming well intervention
• recommendations for filtration flow changes (conformance control, remedial cementing);
• evaluation of bypassed oil targets (infill drilling, side-tracking);
• well health assessment (cross flows behind casing, dual completion, dual injection)

Methodology of reservoir properties study on fluid influx in borehole environment using tracing is based on creating stationary source of label spread in borehole environment of a particular producing well. At every stage of multiphase fracturing, portions of technical water injected into the well through every frac port are labelled with various water soluble chemicals. From the start of operating of traced frac port, regular sampling of produced fluid and subsequent analysis of the presence of injected tracer in it are performed. As the result of analytical interpretation of obtained data, performance parameters of all frac ports under study are defined.

Goals and objectives:

• productivity of each single frac port;
• assessment of flow profile of tested well;
• assessment of unsuccessful frac ports;
• appraisal of mutual influence of adjacent wells drainage area and possible interconnection between different geological objects.

The result:

• estimation and confirmation of fracturing efficiency;
• estimation of present well completion system efficiency.

Before conducting enhanced oil recovery, it is essential to estimate its potential efficiency and to prove the resulting activity efficiency after that. It is done by estimating changes in residual-oil saturation of formation pay zone. Single-Well Chemical Tracer Test (SWCTT) is one of the technologies to estimate residual-oil saturation of formation pay zone. The procedure means injecting oil-soluble and water-soluble tracers into a reservoir and their subsequent holding for some time near the bore of a producing well.
After a certain period of time a well starts producing, at the same time samples are taken at the wellhead and analyzed for the tracers presence in the chemical analysis laboratory. Time difference of oil-soluble tracer returning allows calculating oil saturation of formation pay zone while interpreting obtained concentration of tracers.

Goals and objectives:

• estimation of efficiency of expensive chemical enhanced oil recovery within the strategy to choose displacement agents (surfactants, ASP alkali surfactant polymer and so on)
• estimation of Sorc with the penetration depth of 4-6 mm;
• comparison of Sorc results before and after EOR

The result:

• efficiency determination of chemical enhanced oil recovery under field conditions and making a decision about widespread introduction at a field.