Disclosure of Invention
Aiming at the defects and shortcomings in the prior art, the invention provides a method for determining the horizontal section track of a horizontal well of a roof of a ground coal seam, which aims to solve the technical problem that the longitudinal position and distance of the coal seam of a well track cannot be determined when the track of the horizontal well of the roof is detected in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme:
A method for determining horizontal section track of a horizontal well of a roof of a ground coal seam comprises the following steps:
Step 1, collecting geological data of a target mining area, and drawing an expected geological profile of a horizontal section of a horizontal well according to the collected geological data;
step 2, determining landing points, preset fracturing position intervals and reserved side drilling point intervals of the horizontal section of the horizontal well according to the drawn expected geological profile, and further determining pre-fracturing positions, reserved side drilling points and tracks to be drilled of the horizontal section of the horizontal well;
Step 3, starting coal-detecting drilling of a horizontal section of the horizontal well according to the track to be drilled determined in the step 2 from the landing point, and correcting an expected geological profile according to measurement-while-drilling data and comprehensive logging data acquired in the coal-detecting drilling process to obtain a real-drilling geological profile;
and 4, marking the positions of the coal exploratory holes in the real-drilling geological profile, determining the distance between each fracturing position and the coal seam roof, and finishing the determination of the horizontal section track of the horizontal well of the ground coal seam roof.
The invention also has the following technical characteristics:
Specifically, the step 1 includes drawing the relief contour and the construction position of each rock stratum above the coal seam roof according to the projection azimuth, the longitudinal scale and the transverse scale of the horizontal section in combination with geological data, filling corresponding lithology symbols and construction symbols in each rock stratum, and drawing an expected geological section of the horizontal well.
Still further, step 3 comprises the sub-steps of:
step 3.1, performing coal detection drilling from the landing point to the first pre-fracturing position according to the track to be drilled determined in the step 2;
If coal is seen before drilling to the first pre-fracturing position, and the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is smaller than or equal to 3 degrees, drilling continuously to the first pre-fracturing position by increasing the well inclination in the direction of the declination of the stratum from the coal-finding point, and determining the position of the well section where the coal bed is drilled according to the acquired measurement while drilling data and comprehensive logging data, so as to correct an expected geological profile;
If coal is seen before drilling to the first pre-fracturing position, and the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is larger than 3 degrees, withdrawing the drilling tool to the first reserved sidetrack point, continuing suspending sidetrack construction to the first pre-fracturing position, determining the position of the well section of the drilling meeting the coal bed according to the acquired measurement while drilling data and comprehensive logging data, and correcting the expected geological profile;
step 3.2, finishing drilling of the coal detection in the fracturing section according to the track to be drilled determined in the step 2 in sequence;
if the coal seam is met when the coal probing drilling distance in the fracturing section is less than or equal to half of the preset fracturing position spacing, the coal seam is drilled:
If the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is smaller than or equal to 3 degrees, and the distance between the drilled pre-fracturing position and the top boundary of the coal bed is smaller than or equal to the designed distance between the horizontal section of the horizontal well and the top plate of the coal bed, the well inclination is increased from a coal-seeing point to a downward inclination direction of the stratum, the well inclination continues to drill to the next pre-fracturing position, and the well section position of the coal bed when drilling is met is determined according to the acquired measurement while drilling data and comprehensive logging data, so that an expected geological profile is corrected;
If the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is larger than 3 degrees, or the distance between the drilled pre-fracturing position and the top boundary of the coal bed is larger than the design distance between the horizontal section of the horizontal well and the top plate of the coal bed, determining the position of the well section where the drilling meets the coal bed according to the acquired measurement while drilling data and comprehensive logging data, correcting an expected geological profile, and withdrawing the drilling tool to a reserved sidetracking point for suspending sidetracking construction to the next pre-fracturing position;
if the drilling distance of the coal detection in the fracturing section is greater than half of the preset fracturing position spacing, the coal bed is drilled, and then:
And correcting the expected geological profile according to the position of the well section where the drilling tool meets the coal seam, then withdrawing the drilling tool to a sidetrack point, and continuing suspending sidetrack construction to the next pre-fracturing position.
The design distance between the horizontal section of the horizontal well and the coal seam roof is 0-5 meters.
Further, the preset fracturing position spacing is 30-150 meters.
Furthermore, the distance between the reserved side drilling points is 30-100 meters.
Compared with the prior art, the invention has the beneficial effects that:
According to the method, firstly, an expected geological profile is constructed, then in the drilling process according to the expected geological profile, drilling direction of a drill bit is timely adjusted by means of measurement while drilling data and comprehensive logging data which are obtained in real time and by judging the included angle between the well inclination angle of a well hole and the inclination angle of a coal seam, and the expected geological profile is corrected in real time, so that accuracy of determining the drilling track of the horizontal section of the horizontal well can be greatly improved, drilling meeting rate of the horizontal section is improved, drilling risks caused by insufficient track control precision and high coal feeding rate in the drilling process of the horizontal section of the horizontal well are reduced, and further, staged perforation fracturing construction difficulty is greatly reduced, and fracturing and gas production effects are improved. The method has strong site construction operability and low cost, and is worth of wide popularization and application.
Detailed Description
The embodiments described below are only some, but not all, embodiments of the present invention, and are not limited in any way, and all the embodiments using the technical solutions of the present embodiment, including simple changes, fall within the scope of the present invention.
Technical terms related to the present invention are explained as follows:
And (3) reserving a sidetracking point, namely reserving a sidetracking point (section) on the main borehole at a certain depth according to the requirement of coal exploration, wherein the sidetracking point has the characteristics that the well deviation of the sidetracking point is larger than that of a well section adjacent to the sidetracking point on the main borehole or the azimuth of the sidetracking point is inconsistent with that of the well section adjacent to the sidetracking point on the main borehole.
Example 1
According to the technical scheme, as shown in fig. 1, the embodiment provides a method for determining a horizontal section track of a horizontal well of a roof of a ground coal seam, wherein a is a landing point, and B, C are pre-fracturing positions.
The method comprises the following steps:
Step 1, collecting geological data of a target mining area, and drawing an expected geological profile of a horizontal section of a horizontal well according to the collected geological data;
The collection of geological data of a target mining area can provide a basis for drawing an expected geological profile of a horizontal section of a horizontal well, the geological data mainly comprises a seam floor contour map, an exploration line geological profile map, a single-hole histogram and the like, the seam roof floor lithology combination characteristic, seam roof floor physical property characteristic, natural gamma curve characteristic and well diameter curve characteristic in the range of 20-30 m of a seam roof floor in the projection direction of the horizontal section are obtained through analysis, then the undulating profile and the construction position of each rock stratum above the seam roof are drawn according to the projection direction of the horizontal section, the longitudinal scale and the transverse scale, then corresponding lithology symbols and construction symbols are filled in each rock stratum which are drawn, and the expected geological profile of the horizontal section of the horizontal well is drawn.
Step 2, determining landing points, preset fracturing position intervals and reserved side drilling point intervals of the horizontal section of the horizontal well according to the drawn expected geological profile, and further determining pre-fracturing positions, reserved side drilling points and tracks to be drilled of the horizontal section of the horizontal well;
as a preferable scheme of the embodiment, the design distance between the horizontal section of the horizontal well and the coal seam roof is 0-5 m, the preset fracturing position spacing is 30-150 m, and the reserved side drilling point spacing is 30-100 m.
Step 3, starting to drill coal detection of the horizontal section of the horizontal well according to the track to be drilled determined in the step 2 from the landing point,
Drilling according to an expected geological section and a designed track when drilling before a first pre-fracturing position, drilling to a coal-finding point in the formation inclination direction at a full angle change rate of 1 DEG/30 m-4 DEG/30 m when coal is not seen at the first pre-fracturing position and the coal-finding drilling distance is less than or equal to half of the preset fracturing section interval, and drilling to the coal-finding point in an inclined manner in the formation inclination direction by using the maximum deflecting capability of a drilling tool when the coal-finding drilling distance is greater than half of the preset fracturing section interval. Correcting an expected geological section according to measurement while drilling data and comprehensive logging data acquired in the coal exploration drilling process to obtain a real-drilling geological section;
In site construction, measurement while drilling data comprise well deviation, azimuth and azimuth gamma, comprehensive logging data are mainly obtained through engineering parameter logging, drilling logging, simple hydrographic logging, cuttings logging, gas logging and the like, and comprise hanging weight, weight on bit, drilling time, displacement, drilling fluid consumption, cuttings, full hydrocarbon value, component value and non-hydrocarbon value, and the position and condition of a coal seam well section during drilling can be determined according to the obtained measurement while drilling data and comprehensive logging data.
Step 3.1, performing coal detection drilling from the landing point to the first pre-fracturing position according to the track to be drilled determined in the step 2;
Normally, a coal seam is not drilled before drilling to a first pre-fracturing position, but if coal is seen before drilling to the first pre-fracturing position, and the included angle between the well inclination angle of the well hole and the inclination angle of the coal seam is less than or equal to 3 degrees, the well inclination is increased from the coal-seen point to the downward inclination direction of the stratum, the drilling is continued to the first pre-fracturing position, the position of a well section where the coal seam is drilled is determined according to the acquired measurement while drilling data and comprehensive logging data, and then the expected geological profile is corrected;
the distance between the drill bit and the coal seam can be determined according to the detection range of the measurement while drilling instrument. If the gas survey total hydrocarbon value, hydrocarbon component value and the like rise, the drilling time becomes faster, the drilling pressure becomes smaller, and the upward return rock debris is coal dust, the coal is considered to be already seen.
L=R/tan(α)-M
d=L×sin(α)
Wherein:
R is the detection radius of the measurement while drilling instrument, and the unit is m;
L is the distance between the drill bit and the top surface of the coal seam, and the unit is m;
Alpha is the residual angle of the well inclination angle, and the unit is an angle;
d is the vertical distance of the top surface of the coal seam of the drill bit, and the unit is m;
M is the distance between the drill bit and the measurement while drilling instrument, and the unit is M
If coal is seen before drilling to the first pre-fracturing position, and the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is larger than 3 degrees, withdrawing the drilling tool to the first reserved sidetrack point, continuing suspending sidetrack construction to the first pre-fracturing position, determining the position of the well section of the drilling meeting the coal bed according to the acquired measurement while drilling data and comprehensive logging data, and correcting the expected geological profile;
And 3.2, completing coal detection drilling of each fracturing segment sequentially from the first pre-fracturing position to the last pre-fracturing position according to the track to be drilled determined in the step 2, and forming a fracturing segment between the two pre-fracturing positions.
If the coal seam is met when the coal probing drilling distance in the fracturing section is less than or equal to half of the preset fracturing position spacing, the coal seam is drilled:
If the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is smaller than or equal to 3 degrees, and the distance between the drilled pre-fracturing position and the top boundary of the coal bed is smaller than or equal to the designed distance between the horizontal section of the horizontal well and the top plate of the coal bed, the well inclination is increased from a coal-seeing point to the declining direction of the stratum, the well inclination continues to drill to the next pre-fracturing position, and the drilling-meeting coal bed well section is determined according to the acquired measurement while drilling data and comprehensive logging data, and an expected geological profile is corrected;
If the included angle between the well inclination angle of the well hole and the inclination angle of the coal bed is larger than 3 degrees, or the distance between the drilled pre-fracturing position and the top boundary of the coal bed is larger than the design distance between the horizontal section of the horizontal well and the top plate of the coal bed, determining the position of the well section where the drilling meets the coal bed according to the acquired measurement while drilling data and comprehensive logging data, correcting an expected geological profile, and withdrawing the drilling tool to a reserved sidetracking point for suspending sidetracking construction to the next pre-fracturing position;
After the drilling tool is removed to a suspended side drilling point, a tool surface is arranged, for example, 210 degrees or 150 degrees, then a well section is divided into grooves 10-20 m above the opposite side drilling point, the time is 2-3 hours, 1-2 drilling tools are drilled from the side drilling point along the previous tool surface time control, and the time is 12-24 hours. After 1.5-2 drilling tools are drilled in a time-controlled manner, if the bearing capacity of the drill bit is strong, normal drilling can be resumed. And after 50-150 m of drilling, short-term drilling is performed to repair the side drilling window, so that the drilling tool can smoothly enter a new borehole without swinging a tool face.
If the drilling distance of the coal detection in the fracturing section is greater than half of the preset fracturing position spacing, the coal bed is drilled, and then:
And correcting the expected geological profile according to the position of the well section where the drilling tool meets the coal seam, then withdrawing the drilling tool to a sidetrack point, and continuing suspending sidetrack construction to the next pre-fracturing position.
And 4, marking the positions of the coal exploratory holes in the real-drilling geological profile, determining the distance between each fracturing position and the coal seam roof, and finishing the determination of the horizontal section track of the horizontal well of the ground coal seam roof.
By adopting the method, in the drilling process according to the expected geological section, the drilling direction of the drill bit is timely adjusted by means of the measurement while drilling data and the comprehensive logging data which are acquired in real time and by judging the included angle between the well inclination angle of the well hole and the coal seam inclination angle, and the expected geological section is corrected in real time, so that the accuracy of determining the drilling track of the horizontal section of the horizontal well can be greatly improved, the drilling meeting rate of the horizontal section is improved, the drilling risk caused by insufficient track control precision and high coal entering rate in the drilling process of the horizontal section of the horizontal well is reduced, the construction difficulty of staged perforation fracturing is greatly reduced, and the fracturing and gas production effects are improved.
The individual technical features described in the above-described embodiments may be combined in any certain manner without contradiction, as long as they do not deviate from the idea of the present invention and should also be regarded as the disclosure of the present invention.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the embodiments described above, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the above embodiments may be combined in any certain manner without contradiction, and various possible combinations are not described in detail in order to avoid unnecessary repetition.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.