BACKGROUND

In the petroleum industry, downhole stimulation operations use chemical treatments to improve the rate and amount of oil production. For example, various mineral acids may be used in sandstone rocks to dissolve the rock and other solids, thereby providing a flow path for the formation fluid to flow through and be produced. For carbonate rocks, acids or chelating agents may be used to dissolve calcite during stimulation. Calcite reacts readily with acid and dissolves, enlarging pores and created channels that act as conduits for the formation fluid to flow through and be produced. The high reactivity of calcium carbonate to acids has made acidizing a common practice in carbonate reservoirs.

Although acidizing is common, the treatment process is monitored in a very limited sense. The most common parameters monitored during a chemical treatment include injection pressure, injection rate, downhole pressures, and distributed temperature, each of which may provide information related to the extent of the treatment. However, monitoring methods, such as temperature monitoring, may not be effective in every instance, which may result in poor zonal coverage following chemical treatment and reduced production rates in the production phase. The ability to assess treatment efficiency during stimulation operations to avoid poor zonal coverage and to optimize the efficiency of the chemicals injected based on the formation properties encountered at that injection site remains an important goal.

SUMMARY

This summary is provided to introduce a selection of concepts that are described further below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

In an embodiment a method is described which includes emplacing a sample within a measurement cell, wherein two or more electrodes are configured in the measurement cell; introducing a reactive fluid into the measurement cell; reacting the sample with the reactive fluid, wherein reacting the sample with the reactive fluid results in a change in an ion concentration in the reactive fluid; and measuring the resistivity of the reactive fluid using the two or more electrodes, wherein the resistivity is proportional to the ion concentration in the reactive fluid.

In a further embodiment, a method is described which includes measuring a resistivity of a reactive fluid in contact with a reactive sample and monitoring changes in the resistivity of the reactive fluid as the reactive fluid reacts with the reactive sample.

Other aspects and advantages of the disclosure will be apparent from the following description and the appended claims.

