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: [email protected]