CN102707325A - Azimuth gamma measuring method and equipment - Google Patents

Abstract

The invention discloses a method and equipment for measuring azimuth gamma, which is to install a plurality of gamma detectors on the side of the groove on the drill collar, and the number of gamma detectors can be set to 3 or 4, all using NaI Crystal, when the number of detectors is set to 3, the detectors are spaced 120° apart from each other, and 12 sector azimuth gamma data are recorded during data collection; when the number of detectors is set to 4, the distance between the detectors is 90°, 16 sector azimuth gamma data are recorded during data collection. During the process of drilling, the natural gamma ray azimuth measurement data of the formation is measured by the gamma ray detector, and the real-time uploaded upper and lower azimuth natural gamma ray data can be used to guide the drilling trajectory of the drill bit and quantitatively determine the distance between the drill bit and the radioactive interface; use the obtained Different azimuth natural gamma ray data can form formation azimuth gamma imaging, which can be used to quantitatively evaluate formation dip angle and formation thickness.

Description

A method and device for measuring azimuth gamma

technical field

The invention relates to an azimuth gamma measurement method and equipment, belonging to the technical field of mine geophysical well logging.

Background technique

With the development of the petroleum industry, the number of large-scale integrated oil and gas fields has been decreasing, and the exploration and development of the petroleum industry has turned to subtle and offshore oil and gas reservoirs that are more difficult to explore. In the development of these oil and gas reservoirs, traditional vertical wells have been unable to increase recovery and increase production, and directional wells have emerged to solve this problem. However, the traditional logging methods in horizontal well drilling can no longer meet the needs, so the logging-while-drilling technology suitable for horizontal well drilling has developed rapidly.

In the process of drilling, the measurement of natural radioactivity in the formation is one of the must-test items, and the real-time measurement of natural gamma ray radioactivity in different directions of the formation is of great significance. However, in the existing technical solutions, the gamma ray logging tool only uses a single detector to measure the total count of gamma ray in the formation or measure the gamma ray energy spectrum. Although it can be judged whether the drill bit is drilling in the reservoir, the It cannot be guaranteed that the drilling trajectory of the drill bit is in the reservoir, let alone obtain formation azimuth gamma imaging.

Contents of the invention

The task of the present invention is to provide an azimuth gamma measurement method and equipment, which can guide the drilling trajectory of the drill bit, and can form a formation azimuth gamma imaging map, which can be used to evaluate the formation inclination angle and formation thickness.

Its technical solutions are:

A method for measuring azimuth gamma, which is to install a plurality of gamma detectors on the side of the slot on the drill collar, and serve geosteering according to the gamma azimuth measurement data of the formation measured by the gamma detectors during the drilling process, Formation azimuth gamma imaging is formed for formation evaluation.

The number of the above-mentioned gamma detectors is set to 3 or 4, and NaI crystals are used; the above-mentioned gamma detectors are all located in the same cross-sectional area of the drill collar, and when the number of detectors is 3, the detectors are The intervals are 120°, and when the number of detectors is 4, the intervals between the detectors are 90°.

The above-mentioned gamma detector is placed in the slot, and its front side is sealed. The sealing material is natural rubber with a thickness of 4mm to 6mm, preferably 5mm; the back of the gamma detector is provided with a shielding material. 4mm to 6mm, preferably 5mm; the notch of the drill collar is sealed, and the sealing material is made of beryllium bronze, with a thickness of 8mm to 12mm, preferably 10mm; epoxy is filled between the front sealing material of the gamma detector and the notch sealing material The resin has a thickness of 4 mm to 6 mm, preferably 5 mm.

Further, the groove on the drill collar is a U-shaped groove.

The diameter of the above drill collar is 171.45mm, the diameter of the mud diversion channel of the drill collar is 50~70mm, the length of the gamma detector is 15~20cm, and the diameter of the detector is 25.4mm~35.6mm when three gamma detectors are used. When four gamma detectors are used, the detector diameter is 24.1mm~30.5mm.

The above-mentioned geosteering service is to use the real-time uploaded upper and lower azimuth natural gamma ray data to guide the drilling trajectory of the drill bit, and quantitatively determine the distance between the drill bit and the radioactive interface.

The formation azimuth gamma imaging above is used for formation evaluation by using the natural gamma counts of different azimuths obtained when the detector passes through the radioactive formation, using the obtained natural gamma counts to obtain the formation azimuth gamma imaging map, and using the formation azimuth gamma imaging The map quantitatively evaluates the formation dip angle and formation thickness.

A kind of azimuth gamma measuring equipment, it comprises 3 or 4 gamma detectors, and gamma detector is NaI crystal, and its side is installed on the drill collar, offers groove at the corresponding position of drill collar, and described gamma The horse detectors are all located in the same cross-sectional area of the drill collar, and when the number of detectors is 3, the detectors are separated by 120°; when the number of detectors is 4, the detectors are separated by 90°.

The above-mentioned gamma detector is placed in the groove, and its front side is sealed. The sealing material is natural rubber with a thickness of 4mm to 6mm, preferably 5mm; the back of the gamma detector is provided with a shielding material, and the shielding material is tungsten or lead, with a thickness of 4mm. ～6mm, preferably 5mm; seal the notch where the groove is opened on the drill collar, and the sealing material is made of beryllium bronze, with a thickness of 8mm～12mm, preferably 10mm; epoxy resin is filled between the front sealing material of the detector and the notch sealing material , the thickness is 4mm-6mm, preferably 5mm.

The diameter of the above-mentioned drill collar is 171.45mm, the diameter of the mud diversion channel of the drill collar is 50-70mm, and the length of the gamma detector is 15-20cm. When three gamma detectors are used, the diameter of the detector is 25.4mm-35.6 mm, when four gamma detectors are used, the diameter of the detectors is 24.1mm~30.5mm.

The beneficial technical effect of the present invention is:

In the present invention, a plurality of detectors are slotted on the drill collar and the gamma ray azimuth measurement data of the formation are obtained through the detectors during the drilling process, and the up and down azimuth gamma ray data uploaded in real time can be used to guide the drilling trajectory of the drill bit, and The distance between the drill bit and the radioactive interface can be quantitatively determined; the obtained natural gamma ray data of different azimuths can be used to form azimuth gamma imaging of the formation, which is used to quantitatively evaluate the dip angle and thickness of the formation.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, a brief introduction is made to the accompanying drawings required by the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, Other drawings can also be derived from these drawings without inventive effort.

Fig. 1 is a schematic structural view of the measuring equipment of the present invention; among the figures: 1 is a drill collar, 2 is a mud diversion channel, 3 is a detector, 4 is a sealing material on the front of the detector, 5 is a filling material, and 6 is a slotting sealing material , 7 is the shielding material on the back of the detector, 8 is the photomultiplier tube, and 9 is the electronic circuit;

Fig. 2 is an enlarged schematic diagram of the sectional view along the A direction in Fig. 1 when three detectors are used;

Fig. 3 is an enlarged schematic diagram of the section A in Fig. 1 when four detectors are used;

Fig. 4 is the Monte Carlo calculation model of measuring equipment passing through the radioactive oblique formation; in the figure: 10 is the borehole, 11 is the sandstone formation, and 12 is the radioactive mudstone formation. The calculation conditions are: the formation is a horizontal layered formation, and the well axis is On the Z axis, the coordinate origin O is at the center of the formation, and the formation size is 300cm×300cm×800cm; the wellbore is filled with fresh water, and the diameter of the wellbore is 20cm; the porosity of the sandstone formation is 30%; the shale content of the radioactive mudstone formation is 80%, U Th content is 5ppm, Th content is 10ppm, and K content is 5%; the angle between the radioactive mudstone formation and the X-axis direction is 80°, and the thickness is 40cm; the axis of the drill collar coincides with the well axis, and the diameter of the drill collar is 171.45mm. The diameter of the channel is 50mm; measured by 4 detectors, the length of the detector is 20cm, and the diameter is 25.4mm;

Fig. 5 is the upper and lower azimuth natural gamma ray curves obtained by using the Monte Carlo calculation model in Fig. 4 when the measuring equipment passes through the radioactive oblique formation; in the figure: A=0° indicates the upper azimuth natural gamma ray measurement data; The lower azimuth natural gamma ray measurement data; D represents the distance between the detector and the coordinate origin O, which is expressed as a negative number when the detector is located on the left side of the coordinate origin O, and expressed as a positive number when the detector is located on the right side of the coordinate origin O; N _γ represents the natural gamma count;

Fig. 6 is the Monte Carlo calculation model of the measuring instrument passing through the inclined radioactive interface. The calculation conditions are: the formation is a horizontal layered formation, the well axis is taken as the Z axis, the coordinate origin O is at the formation center, and the formation size is 300cm×300cm×800cm; The wellbore is filled with fresh water, and the borehole diameter is 20cm; the porosity of the sandstone formation is 30%; the shale content of the radioactive mudstone formation is 80%, the U content is 5ppm, the Th content is 10ppm, and the K content is 5%; the inclined radioactive interface and The intersection point of the well axis is at the origin; the axis of the drill collar coincides with the well axis, the diameter of the drill collar is 171.45mm, and the diameter of the mud diversion channel is 50mm; four detectors are used for measurement, the length of the detector is 20cm, and the diameter is 25.4mm;

Fig. 7 is the relationship curve between the distance ΔD between the upper and lower azimuth gamma curve change points and the formation interface inclination angle α when the measuring equipment passes through the radioactive formation with different inclination angles obtained by using the Monte Carlo calculation model in Fig. 6;

Fig. 8 is the azimuth gamma imaging diagram obtained by using the Monte Carlo calculation model in Fig. 4 when the measuring equipment passes through the radioactive oblique formation; in the figure: A represents different data recording azimuths; D represents the distance between the detector and the coordinate origin O , when the detector is located on the left side of the coordinate origin O, it is represented by a negative number, when the detector is located on the right side of the coordinate origin O, it is represented by a positive number; 13 represents the high count area of natural gamma, 15 represents the low count area of natural gamma; 14 represents Transition region between high and low natural gamma count regions.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

A method for measuring azimuth gamma, which is to install a plurality of detectors on the side of a slot on the drill collar, and obtain formation gamma azimuth measurement data through the detectors during the drilling process, and use the upper and lower azimuth natural gamma data uploaded in real time It can guide the drilling trajectory of the drill bit and quantitatively determine the distance between the drill bit and the radioactive interface; the measured natural gamma ray data of different azimuths can be used to form formation azimuth gamma imaging, which is used to quantitatively evaluate the formation inclination angle and formation thickness.

Fig. 1 is a schematic structural diagram of the measuring device of the present invention, and Fig. 2 and Fig. 3 are respectively enlarged schematic diagrams of the A-direction cross-section in Fig. 1 when 3 gamma detectors and 4 gamma detectors are used. As shown in the figure, multiple gamma detectors are slotted on the side of the drill collar 1 to obtain formation natural gamma ray azimuth measurement data. The mud diversion channel 2 of the drill collar 1 can transport enough mud required for drilling. Its minimum diameter is 50~70mm.

Drill collar 1 has a U-shaped slot, detector 3, detector front sealing material 4, filling material 5, slot sealing material 6, detector back shielding material 7, photomultiplier tube 8, and electronic circuit 9 are placed in the drill collar 1 slotted.

The number of detectors 3 is 3 or 4, all of which are NaI crystals, and the detectors 3 are all located in the same cross-sectional area of the drill collar. When 3 gamma detectors are used, the detectors are spaced 120° apart from each other, and each gamma detector records 4 azimuth natural gamma data during data collection, and the azimuth natural gamma data of 12 sectors are recorded in total; when using When there are 4 gamma detectors, the detectors are spaced 90° apart from each other. During data collection, each gamma detector records 4 azimuth natural gamma data, and a total of 16 sector azimuth natural gamma data are recorded.

The length of the detector 3 is 15~20cm; taking the diameter of the drill collar 1 as 171.45mm as an example, the diameter of the detector 3 is 25.4mm~35.6mm when three gamma detectors are used, and the detection The diameter of the device 3 is 24.1mm~30.5mm; the back of the detector 3 needs to be shielded, and the shielding substance 7 on the back of the detector is made of tungsten or lead, with a thickness of 5mm.

The following uses the Monte Carlo numerical simulation method to illustrate that an azimuth gamma measurement method and equipment provided by the present invention can serve geosteering, and can form formation azimuth gamma imaging for formation evaluation.

1. Geosteering

Using the real-time uploaded upper and lower azimuth natural gamma ray data, it is possible to qualitatively judge the formation encountered by the drill bit, and to quantitatively judge the distance between the drill bit and the radioactive interface

(1) Qualitatively judge the formation drilled by the drill bit

Using the Monte Carlo numerical simulation method, the calculation model under the condition of drilling is established, as shown in Figure 4, the equipment shown in Figure 1 is placed in the borehole, and the simulation calculation and measurement equipment pass through the natural gamma ray curve of the upper and lower azimuths of the radioactive inclined formation , as shown in Figure 5. It can be seen from Fig. 5 that when the measuring instrument is in a non-radioactive sandstone formation, the upper and lower azimuth natural gamma ray curves coincide, but when the instrument encounters a radioactive mudstone formation, the upper and lower azimuth natural gamma ray curves are different, which can be qualitatively judged when drilling. Drilling into radioactive formations.

(2) Quantitatively determine the distance between the drill bit and the radioactive interface

Using the Monte Carlo numerical simulation method, a calculation model under the condition of drilling is established, as shown in Figure 6, the equipment shown in Figure 1 is placed in the wellbore, and the angle of the inclined radiation interface (the angle between the inclined radiation interface and the X-axis direction is changed) ) is 40°, 50°, 60°, 70°, 80°, 85°, simulate the natural gamma ray curves of the upper and lower azimuths of the radioactive interface at different inclination angles, and obtain the natural gamma ray of the upper and lower azimuths when the equipment encounters radioactive formations The relationship curve between the distance ΔD of the point where the curve changes and the angle α (converted into radians) of the inclined radioactive formation interface is shown in Fig. 7.

The curve fitting of the data points in Fig. 7 shows that the relationship between the inclination angle α of the formation interface and the distance ΔD between the change points of the natural gamma ray curve in the upper and lower azimuths is as follows:

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1.523</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.967</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;D</span>}}{\mathrm{<span\; class="notranslate">\; 84.754</span>}}}$

When the natural gamma ray curve changes in the upper and lower azimuths, that is, the gamma detector just detects the radioactive formation, at this time the vertical distance between the gamma detector and the radioactive interface is the detection depth (DEP) of the natural gamma ray logging, and the detection depth (DEP ) is a constant, so it can be concluded that the distance between the drill bit and the radioactive interface in the drilling direction at this time is:

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; DEP</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="d"\; filenames="HDA00001690404900032.png,HDA00001690404900042.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}$

In the formula, _d0 is the distance between the detector and the drill bit.

Putting the relationship between α and ΔD into the above formula, we can get,

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; DEP</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1.523</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.967</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;D</span>}}{\mathrm{<span\; class="notranslate">\; 84.754</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="d"\; filenames="HDA00001690404900032.png,HDA00001690404900042.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}$

Then, the distance between the drill bit and the radioactive interface in the drilling direction after the detector detects the radioactive formation can be calculated according to the drilling speed of the drill bit.

2. Azimuth Gamma Imaging

Using the Monte Carlo calculation model shown in Figure 4, record the natural gamma counts of 16 azimuths at different positions when the measuring equipment passes through the radioactive oblique formation. Figure 8 shows.

Using the azimuth gamma imaging diagram shown in Fig. 8, the formation inclination angle can be obtained as:

α=arctan(BC/P)

In the formula, point B is the color mutation point in the imaging image when the detector penetrates the radioactive formation at the 180° azimuth, that is, the detector at the 180° azimuth just detects the position of the radioactive formation; point C is the detector at the 0° azimuth When penetrating into the radioactive stratum, the color mutation point in the image map means that the 0° azimuth detector just detected the position of the radioactive stratum; BC indicates the distance between point B and point C on the well axis, which is shown as point B and point C on the map The vertical distance; the distance P is a fixed parameter and needs to be scaled. Under the simulation conditions, P is 27cm.

The thickness H of radioactive oblique formation is:

H=EF·sin(90°-α)

In the formula, point E is the color change transition point in the imaging image when the detector penetrates the radioactive formation at the 180° azimuth, and this position is the position where the detector enters the radioactive formation at the 180° azimuth; point F is the detection position at the 180° azimuth When the detector passes through the radioactive formation, it is a sudden change point in the imaging image. This position is the position where the detector passes through the radioactive formation at 180°. At this time, the position of the radioactive formation just cannot be detected; EF indicates the distance between point E and point F on the well axis, In the figure, it is expressed as the vertical distance between point E and point F.

According to the data on the azimuth gamma imaging map, it can be concluded that the slope angle of the radioactive formation is α=79.9°, and the thickness of the radioactive formation is H=40.6cm. In the model, the real stratum inclination angle and stratum thickness are 80° and 40cm, respectively, and the error of radioactive stratum inclination angle and thickness obtained by using the imaging map is less than 1%. It can be seen that the stratum inclination angle and stratum thickness can be quantitatively evaluated by using the stratum azimuth gamma imaging map, and the error is low.

Claims (10)

1. a kind of azimuth gamma measuring method, it is characterized in that: a plurality of gamma detectors are installed on the side of the groove on the drill collar; Geosteering service, and formation azimuth gamma imaging for formation evaluation. 2. a kind of azimuth gamma measuring method according to claim 1, is characterized in that: the number of described gamma detector is set as 3 or 4, all adopts NaI crystal; Located in the same cross-sectional area of the drill collar, and the number of detectors is 3, the detectors are spaced 120° apart from each other, and when the number of detectors is 4, the detectors are spaced 90° apart from each other. 3. A method for measuring azimuth gamma according to claim 1 or 2, characterized in that: the gamma detector is placed in a slot, its front side is sealed, and the sealing material is natural rubber with a thickness of 4 mm to 6 mm The back of the gamma detector is provided with a shielding material, the shielding material is selected from tungsten or lead, and the thickness is 4mm-6mm; the slot of the drill collar is sealed, and the sealing material is beryllium bronze, and the thickness is 8mm-12mm ; filling epoxy resin between the front sealing substance of the gamma detector and the notch sealing substance, with a thickness of 4 mm to 6 mm. 4. A method for measuring azimuth gamma according to claim 1, characterized in that: the groove on the drill collar is a U-shaped groove. 5. A method for measuring azimuth gamma according to claim 1, characterized in that: the diameter of the drill collar is 171.45 mm, the diameter of the mud diversion channel of the drill collar is 50-70 mm, and the gamma detection The length of the detector is 15-20cm, and the diameter of the detector is 25.4mm-35.6mm when three gamma detectors are used, and the diameter of the detector is 24.1mm-30.5mm when four gamma detectors are used. 6. A kind of azimuth gamma measurement method according to claim 1, characterized in that: the geosteering service is to use the real-time uploaded upper and lower azimuth natural gamma data to guide the drilling trajectory of the drill bit, and quantitatively determine the distance between the drill bit and the radioactivity interface distance. 7. a kind of azimuth gamma measuring method according to claim 1, is characterized in that: described formation azimuth gamma imaging is used for formation evaluation and is to utilize the natural gamma counting of different azimuths when detector passes through radioactive formation, The formation azimuth gamma imaging map is obtained by using the obtained natural gamma ray counts, and the formation inclination angle and formation thickness are quantitatively evaluated by using the formation azimuth gamma ray imaging map. 8. An azimuth gamma measuring device is characterized in that: it comprises 3 or 4 gamma detectors, and the gamma detectors are NaI crystals, which are side mounted on the drill collar, and recessed holes are set at the corresponding positions of the drill collar. The gamma detectors are all located in the same cross-sectional area of the drill collar, and when the number of detectors is 3, the detectors are spaced 120° apart from each other; when the number of detectors is 4, the distances between the detectors are 90°. 9. The azimuth gamma measuring device according to claim 8, characterized in that: the gamma detector is placed in the groove, its front side is sealed, and the sealing material is natural rubber with a thickness of 4 mm to 6 mm; The back of the gamma detector is provided with a shielding material, the shielding material is selected from tungsten or lead, and the thickness is 4mm to 6mm; the notch of the groove on the drill collar is sealed, and the sealing material is made of beryllium bronze, and the thickness is 8mm to 12mm; Fill epoxy resin between the sealing substance on the front of the detector and the sealing substance of the notch, with a thickness of 4mm to 6mm. 10. The azimuth gamma measuring device according to claim 8 or 9, characterized in that: the diameter of the drill collar is 171.45mm, the diameter of the mud diversion channel of the drill collar is 50-70mm, and the diameter of the gamma The length of the horse detector is 15~20cm. When using 3 gamma detectors, the diameter of the detector is 25.4mm~35.6mm. When using 4 gamma detectors, the diameter of the detector is 24.1mm~30.5mm .

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