www.gradient-geo.com 1 © 2005-2016 CJSC Gradient

Full-Wave Location Method (FWL)

In 2011, CJSC Gradient has developed the Full-Wave Location method (FWL) which has significant advantages over the world

analogues. This method can be successfully used to solve geological tasks related to exploration and development of hydrocarbon de-posits.

Application of FWL method

Our company provides a full cycle of seismic emission monitoring surveys. The FWL technology can be used to solve both geolog-ical and technological challenges. Range of solutions has been tested and approved for implementation at oil and gas fields, some of them are unique. Range of tasks:

• Microseismic hydraulic fracturing monitoring to provide evaluation of dynamics, dominant direction of fractures and to estimate zones of proppant penetration. Geophysical measurements are conducted from the ground surface, without trip of equipment in neighboring wells. During detection of microseismic events not only their location but also seismic moment tensor are defined;

• Microseismic active fracturing zones monitoring to identify active fracturing zones and to determine the orientation of the fractures. It is vital task in the design of horizontal wells and side tracks;

• Monitoring of the fluid injection process into the reservoir to determine injection fluid migration paths.

Processing and interpretation

ЗАО "Градиент" 420045, г. Казань ул. Николая Ершова, д.29 Тел./факс: +7 (843) 20-01-099 E-mail: mail@gradient-geo.com

www.gradient-geo.com 2 © 2005-2016 CJSC Gradient

Equipment

Name Unit Baikal -ACH88

SCOUT

Amount of inlet channels

3 3

ADC resolution

24 24

Sampling frequency Hz 100-4000 125-4000

Operating-temperature range °С -40… +60 -40… +70

Name Unit СМЕ-4111-

LT

LE-3Dlite

Conversion coefficient V/(m/s) 4 000 400

Output signal type

analog

Frequency bandwidth Hz 0.1 - 20 1 - 80

Operating-temperature range °С -40...+55 -15... +65

Principal physics

Principle of the Full-Wave Location method is based on evaluation of the likelihood function of the known signal presence in the signal-noise mixture. For this it is necessary to know useful signal (responses from deep source). Useful signal is a full-wave process that registered by three components on observation points that located at the surface. The signals are calculated by 3D numerical simu-lation of wave processes in seismo-mechanical model that created using information from structural maps and VSP data. The source of wave process is the force that applied to nodes around the visualization point in the directions determined by the seismic moment tensor components. This approach allows in the best way to locate and identify the type of event and its characteristics under conditions of low signal / noise ratio at the receiving channels.

Advantages

• Field survey is conducted from ground surface using highly sensitive broadband seismometers, without trip of equipment in neighboring wells;

• The location is done by 3 components of the full wave process form, including all wave types;

• Location procedure automatically takes into account different level of surface noise on the channels. The most noisy channel does not affect the outcome.

• Full tensor of seismic events as well as its location are retrieved. Maximum likelihood method allows to accurately locate seismic events even when the signal / noise ratio at the receiving channels equals to 1/100.

Results

As a resultof FWL method processing interpreter receives:

• Coordinates of seismic events;

• The components of the tensor seismic moment: events, its own values and vectors;

• Type of seismic event (VOL, DC, CLVD);

• Event confidence estimation (S/N);

• Dynamics of events occurrence.

Interpretation is based on comparison of event location results with the different geological-geophysical information that depends on the task.

SCOUT Baikal-ACH88 LE-3Dlite CME-4111-LT

Recording

devices

Highly sensitive

three-component

seismometers

Fracturing forecast map

Gross microseismic activity

Gross microseismic activity during stage №1

Gross proppant invaded zone