Work experience and historic reference
- 2004 – works commencement. Surveys in the fields of Bashneft Joint Stock Oil Company.
- From 2006 – up to 30 wells per year are in production mode. Horizontal well bores are up to 500 m in length.
- From 2008 – up to 40 wells per year. Survey of operating horizontal wells owned by Rosneft Oil Company JSC. Horizontal well bores are more than 1,000 m in length.
- 2009 – surveys in the Republic of Kazakhstan. Horizontal well bores are up to 500 m in length.
- As of today - approximately 50 wells per year.
Downhole logging tools and equipment
AGAT-KG-42-6V (manufactured by Geofizika Research and Production Company)
These devices feature 6 moisture meter sensors allocated along the device perimeter on outboard supports, which enables composition scanning along the whole surface of horizontal well bore cross section.
Length – 3.5m
Diameter – 42 mm
Operation in 52-200 mm diameter wells
RVS high-sensitivity flowmeter module:
- flow meter
- 6 moisture meters
- moisture meter
- pressure gauge
- flow meter
- collar finder
- resistivity meter
- inflow thermal indication (well thermal indicator)
- instrument inclination angle
RVS high-sensitivity flowmeter module - 6 moisture meter sensors, as well as a thermometer and a high sensitivity
In case of wellhead pressure, ShTK 65x35 lubricator units are used.
Technical characteristics: Maximum pressure – 350 atm Internal diameter – 65 mm
Instrument conveyance technologies
- Rigid logging wire - in wells with horizontal well bore of up to 300 m in length - mostly Urals-Volga Region. No wellhead pressure, development mode with compressor or swab.
- Bottom tractor - this method has been worked out when surveying flowing wells in the fields of East Siberia with wellhead pressure up to 700 atm and horizontal well bore length more than 1,000 m. The bottomhole tractor was also used during surveys with lubrication unit for well-logging.
- Coil tubing - in wells operated in flowing mode or with buffer pressure at the wellhead (especially in wells with high gas content). The length of the horizontal section under survey is up to 600 m (in case of no pollution and the trajectory is "successful" - up to 1,000 m).
Logging tool is conveyed with a rigid logging wire
One of the simplest options for horizontal wellbore survey arrangement is to connect it to a serial logging wire wound around the standard logging truck, and then cut the rigid cable.
- possibility to convey any types of logging tools to the bottomhole, considerable reduction of time spent on log survey (1.5 - 2 times);
- good permeability with small curvature radii and borehole diameters;
- possibility to perform surveys with regard to control development using standard wellhead equipment and existing technologies;
- possibility to measure the cable and, as a result, high accuracy of various methods diagrams referencing to the section;
- low accident rate;
- used in cased wells, in the open borehole of directional and horizontal wells of up to 300 m in length.
Survey throughout the well bore is not always possible when this method is used in complex directional and horizontal wells of more than 200 m in length.
1 - intermediate casing;
2 - logging wireline;
3 - special collar;
4 - semi-rigid light weight wireline part;
5 - well-logging equipment;
6 - heavy weight wireline part.
Rigid Cable method
The tractor moves along the horizontal well bore due to the engine operation and pushes surveying apparatus in front.
The tractor comprises:
- two stable stabilizers;
- collar locator;
- two sets of extendable traction wheels;
- device for head tension determination;
- electronics section ensuring complete controllability of the tractor and delivery of the information concerning its condition to the surface system.
- The tractor control requires only a small power supply panel and a laptop.
- Easy in operation and transportation.
- Capable of servicing various diameter wells regardless of the horizontal well bore length.
- The borehole tractor method is simpler, cheaper and safer method to convey measurement system to horizontal wells.
WellTec borehole tractor
|Length||5,33m XR||5,8m XR||5,5m XR|
by assembly diameter
|55,9-233,7 mm||86,4-320,0 mm||115,6-487,7 mm|
* Pulling force and speed can be configured to attain optimal force-speed ratio
** All models can be used for working in an open borehole
Coil tubing unit
Ensures conveyance of logging tools and communication with the surface recording system.
Pipe diameter 36 – 40 mm.
Pipe length of up to 5 km.
Horizontal section length of up to 1 km (in favorable conditions).
Features of processes in horizontal wells (HW)
Flow structure in horizontal wells differs from the flow structure in vertical wells and is determined by multi-phase flow, non-monotonicity of the well bore trajectory in the horizontal section (availability of ascending and descending sections), influence of gravity field on phases distribution in the flow.
Results of the multi-phase flows research using the horizontal well model showed that distribution of fluid phases is inhomogeneous along the well bore cross-section and is changing along the well bore, depending on the angle.
Methods of the phase flow rates quantitative determination
Flow conditions in the horizontal well boreе
- Phase flow rates are set: Qg, Qo, Qw (according to wellhead data).
- Calculation of flow properties of Hg, Ho, Hw flow (volume content). Flow regime is determined.
- Calculation of the volume content of each phase in HW: Hw, Ho, Hg.
- Taking into account the inflow profile along the well bore built in accordance with the indication downhole flowmeter and volume contents - Hg, Ho, Hw, phase flow rates are determined by intervals.
fluid properties (PVT):
- interphase tension ratio.
- zenith angle;
- internal diameter.
- mechanical flow meter;
- volume content of phases (distributed hydrometer);
- data on inflow at the wellhead.
As a result:
Calculation of the volume content of each phase.
Flow rate of each inflow interval by phases (integral and differential inflow profile).
Example of determining phase flow rates
According to the research results, operation of all filters in the HW interval is noted. Inflow composition: gas+oil.
Also, a slight inflow is noted from the bottom-hole. Inflow composition - oil and gas with low water content.
According to the research results, operation of all filters in the HW interval is noted. Inflow composition: gas+oil. Also, there is little amount of water in the inflow composition below 3,195.0 m.
Coil tubing unit