Development of

geophysical technologies

for old-stock gas wells investigations

GITAS VNIIGIS

IGU Working Committee 2, April 2008, Salzburg

GITAS and VNIIGIS companies together with GAZPROM carry out the next geophysical and technological service for old UGS wells:

1. Casing wear evaluation

2. Detecting gas-accumulation zones and their location in the inter-string and behind-the-casing areas

3. Evaluation of caverns formed in close to well zone of high-debit terrigenous reservoir

4. Casing and cement bond sampling by drilling corer and following analysis

5. Detecting technogeneous gas-accumulation zones in the crosswell reservoir space

6. Getting additional geological data in operating gas wells on a base of gamma-spectrometry methods

7. Branch hole drilling with the help of electromagnetic channel directional geosteering using inert gas or foam

1. Casing wear evaluation by

electromagnetic flaw detection

Means:

Magnetic-Impulse Flaw-Detecting and

Thickness Measuring Equipment

MID-K

Advantage:

Operation in multistring wells

Fig. 1 Example of thickness measuring in a dual-string well section

Fig. 2 The example of through tubing detection of production string corrosion

2. Detecting gas accumulation zones

and their location in the inter-string

and behind-the-casing areas

Measuring conditions:

Gas-filled borehole

Tubing

Production and protective strings

Means of solving the problem:

Logging with different depth multisonde modifications of

neutron methods tools (neutron logging, induced spectral

gamma-ray logging, pulsed neutron logging)

Fig. 3 Example of gas accumulation zones detecting in the inter-string and behind-the-casing areas near the wellhead

Fig. 3 The next example of gas accumulation zones detecting in the inter-string and behind-the-casing areas near the wellhead

3. Evaluation of caverns formed close to

well zone of high-debit terrigenous

reservoir

Measuring conditions:

Gas-filled borehole

Tubing

Perforated production string

Means of solving the problem:

Logging with different depth multisonde modifications of

neutron methods tools (neutron logging, induced spectral

gamma-ray logging, pulsed neutron logging)

Fig.5 Cavern detection and cementing estimation

Fig.6 Cavern detecting, measuring its demensions and estimating the outside string area cementing

Fig.7 Comparison of investigation results before and after well repair works

4. Casing and cement bond sampling

by drilling corer and following

analysis

It is a topicality for gas wells with high

hydrogen sulphide content in gas

Fig.8 Production string and cement bond sample selected

by the SKT-3M drilling corer

5. Detecting technogeneous gas

accumulation zones and migration ways

by electrometry and crosswell seismic

tomography methods

Means:

KASKAD equipment for electrometry

MSAT equipment for crosswell tomography

Fig .9 Example of zones of secondary gas and water accumulation at a depth of 198 m of UGS section determinated

Fig.10 Gas migration

ways and gas

accumulation areas

detecting by crosswell

seismic tomography

6. Getting additional geological data

in operated gas wells with

gamma-spectrometry methods

(natural gamma-ray spectrometer,

induced spectral gamma-ray

logging)

Fig.11 Percentage-models obtaned by the spectrometry data

(natural gamma-ray spectrometer, induced spectral gamma-ray logging)

7. Directional wells geosteering with

electromagnetic channel while

drilling the branch hole (MWD) using

inert gas or foam

Fig.12 Small-diameter telemetry system ZTS-42(54)EM

предназначена для инклинометрических измерений в процессе бурения боковых стволов из нефтяных и газовых скважин.

Особенности и преимущества

сокращает время бурения скважин, позволяет производить измерения без остановки бурения;

повышает качество проводки;

позволяет управлять траекторией бурения наклонно-направленных и горизонтальных скважин с радиусом кривизны до 12-15 м;

обладает возможностью измерения в статике.

Технические характеристики

Диапазон измерений, град.:

зенитный угол 0-180±0,1

азимут 0-360±1,5

визирный угол 0-360±1

Габаритные размеры скважинного прибора, мм

диаметр модулей 42; 54

длина модулей по муфтам 105

длина модулей 1000

Вес скважинного прибора, кг 50

CONCLUSIONS

First of all the presented technologies used for old–stock gas wells mean to control technic condition of boreholes and impermeability of USG. Flaw detection, neutron methods, electrometry give an advantage and economical efficience due to the fact that they needn’t tubing lifting . As for technologies such as seismography and directional wells geosteering, they are also efficient because they allow to detect gas accumulation areas and to increase the output of old stock gas wells.

Contacts

Address: GITAS JSC, Gorkogo str. 1,

Oktyabrsky, Bashkortostan, Russia,

452614

E-mail: npf-gitas@bk.ru

mamleev@gitas.ru