Oil & Gas Well Selection Criteria

• Provide geotechnical info on the potential oil extraction sites subject to a treatment

• Provide completed surveys on oil and gas wellbores appropriate for the further treatment

• Provide general geological info on oil and gas deposits (note if there are any aquifers located nearby)

• Provide structural deposit maps including wellbore indexation according to the completed surveys and mentioning debits and water encroachment factor for the neighboring wells

Oil & Gas Well Selection Criteria

In case of experimental works the chosen oil wellbores must comply with the following requirements:

1. Requirements for construction and type of the wellbore appropriate for the treatment:

1.1 The oil wellbore must be vertical;

1.2 The productive part of the formation must be provided with casing;

1.3 The technical state of the wellbore must be satisfactory enough (the operational column is sealed, no shrinkages or cross-flows behind casing)

1.4 The volume of the operational column from the current bottom hole to the upper perforation holes must comprise at least 1 м3. (V=πd2h/4, 'd' stands for the internal diameter of the operational column; 'h' stands for distance from the current bottom hole to the upper perforation holes. V≥1м3).

1.5 The perforation holes density must be at least 12 perforation holes per linear meter at the moment of formation opening

1.6 In case of annular space packer being installed into the well, it must be feasible to dismantle the packer for the duration of the operations;

1.7 The oil well tubing length must comply with the wellbore depth.

2. Requirements for the geophysical peculiarities of the productive formation:

2.1 The productive horizon must comprise either terrigenous or carbonate rock;

2.2 The depth of occurrence of the productive formation may vary from 1000 meters up to 3000 meters;

2.3 The pressure of the formation must be approximately equal to the hydrostatic pressure in the wellbore;

2.4 The water encroachment factor of the formation fluid must not exceed 85 percent;

2.5 The aquifer must not be closer than 100 meters to the productive formation;

2.6 The geophysical data must be indicative of hydrocarbon resources presence (total resource depletion must be excluded) and of the productive formation capacity;

2.7 The formation fluid must not contain any mechanical impurities.

In order to research the influence of the HTBC technology implementation on terrigenous and carbonate collectors of the wellbore exploiting company, it is necessary to conduct a comprehensive research (before the technology implementation and after the implementation), including:

*The following list represents the full spectrum of geophysical research although the formation characteristics after the HTBC implementation can be monitored with the help of very few research methods, including: permeability parameters analysis, determination of the formation flow coefficient, fluid-movement profile and recovery characteristic curve (RCC).

Effect Estimation Criteria

Research

• Injectivity test of the wellbore in different working modes (it is acceptable to conduct the testing
of the wellbore in one working mode or follow the RCC method as well) including wellhead and
bottom hole parameters measurements together with the further bottom hole zone filtration
coefficient determination (productivity coefficient, flow capacity and permeability);

• Pressure recovery curve (PRC) analysis of the zone, distant from the wellbore, together with
the further filtration coefficient determination (flow capacity, permeability, piezoconductivity and
skin-factor);

• Comprehensive research on the formation (with the help of gamma-ray logging, casing collar
locator, mechanical debit metering, moisture metering, mud-resistivity logging, thermal logging
and barometry), that determines the depth of the current bottom hole zone, oil and water flow
intervals, probable cross-flows behind the casing and hermeticity of the artificial bottom hole zone;

• Analysis of the oil properties in conditions of the formation, including downhole oil sampling for wellbores with higher formation pressure than the saturation pressure or grab oil sampling and compiling the formation oil sample for wellbores with lower formation pressure than the saturation pressure; and the further examination of downhole or grab oil samples.

• Analysis of oil and gas content under the condition of standard separation and differential liberation including the determination of volume ratio, saturation pressure, density, viscosity, molecular mass, isothermal compressibility and isobaric expansion coefficients.

• Determination of the physicochemical characteristics of the degassed oil under normal condition: density, viscosity, water content, salt content, mechanical impurities content, setting point, saturated vapor pressure; sulfur, organochlorine compounds, asphaltenes, resins and paraffin content, fractional and component oil content, component analysis of separation gas content under the condition of varying formation pressure and separation pressure.

Wellbore Output Measurements

In order to measure the wellbore output (before the technology implementation and after the implementation), we suggest providing the candidate wellbores with fluid meters to ensure daily monitoring of the wellbore debit. Additional wellbore capacity measurements must be held once a week.

The wellbore exploiting company must mention the appropriate period of the wellbore output measurements before the technology implementation and after the implementation, taking the further optimal oil production technological parameters into account.