CN107676038B - While-drilling geosteering method for horizontal well trajectory in inclined thin reservoir - Google Patents
While-drilling geosteering method for horizontal well trajectory in inclined thin reservoir Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/046—Directional drilling horizontal drilling
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/02—Determining slope or direction
- E21B47/026—Determining slope or direction of penetrated ground layers
Abstract
The invention discloses a method for geosteering while drilling of a horizontal well track in an inclined thin reservoir, which mainly guides normal drilling of a horizontal well in the inclined reservoir by using theoretical calculation of apparent thickness and true thickness of the horizontal well. The horizontal well drilling can be realized by executing the following operation steps, and the specific method steps are as follows: 1) basic data analysis, and collection, sorting and analysis of earthquake, geological, well logging, well drilling and production data; 2) calculating the apparent thickness and the true thickness of the forward reservoir; 3) calculating the apparent thickness and the true thickness of the reverse reservoir; 4) and main measures are taken for reservoirs with different tendencies to ensure normal drilling of the horizontal well. The method can fully utilize geological, logging and well drilling information in the development block, has the characteristics of comprehensive consideration, simplicity in operation and better accordance with actual conditions, can ensure effective drilling of the horizontal well, and provides technical support for oil and gas exploration and development.
Description
Technical Field
The invention relates to a while-drilling geosteering method for a horizontal well track, in particular to a while-drilling geosteering method for a horizontal well track in an inclined thin reservoir, and belongs to the technical field of petroleum exploration application.
Background
With the national emphasis on land and environmental protection, many new and old oil and gas fields are developed by directional drilling gradually, and for difficultly developed oil and gas reservoirs such as cities, mudflats, deserts, oceans and the like, large-inclination directional or horizontal well development is gradually adopted; the maximum inclination angle of the high-inclination directional well is usually 46-85 degrees, and the inclination angle of the horizontal well is 86-120 degrees; when the reservoir in the reservoir is inclined, the thickness of the reservoir drilled by directional drilling has certain error with the thickness of the reservoir in a real reservoir, if the reservoir is not corrected correctly, the error of the reservoir thickness often causes the wrong understanding of underground oil reservoirs for the reservoir (or oil layer) with thin thickness and large change of the reservoir inclination angle, so that the drilling rate of the oil layer of the horizontal section of the newly drilled horizontal well is low, and even the drilling error is caused; how to adopt some methods to correct the real thickness of the reservoir, and provide basis for reasonably knowing the oil reservoir, accurately guiding the geology of the horizontal well, improving the drilling rate of the oil reservoir in the reservoir and effectively developing the oil field.
The geosteering technology is generally composed of two parts, firstly, based on the category of drilling and well logging tools, since 90 s, foreign companies such as Anadrill, Halliburton, Baker Hughes, INTEQ and Statoil have successively developed respective drilling geosteering tools, and mainly the underground data are transmitted to the ground by using the measurement while drilling tool to assist the drilling of a horizontal well; the units such as China Medium oil geological logging company, Beijing Petroleum exploration institute, Zhonghai oil and the like in the late 90 s begin to introduce, digest and independently research and develop geosteering tools, and domestic experts (Suyi brain, etc., 1996; Linguanghui, etc., 2000;) discuss geosteering drilling technology and research progress thereof in China; secondly, a geological guiding while drilling geological evaluation method is established, particularly how to combine a while drilling tool with geological knowledge to guide effective drilling of a horizontal well and continuously improve the drilling rate of an oil layer, and domestic scholars (maybe Lei, 2002; honor and delay, 2003; Yuanzhipeng, 2005; Jianlinjun, 2005) mainly evaluate the actual application of the geological guiding tool in the oil reservoir; the method is characterized in that (Liuyansong and the like, 2007; Saturn pine and the like, 2009) scholars estimate and evaluate the inclination angle of a reservoir, but the apparent thickness and true thickness theoretical calculation method of the horizontal well is not established systematically, and meanwhile, the application range of the calculation method is not evaluated.
In the reservoir stratum of the inclined reservoir stratum at home and abroad, a drill bit is rarely analyzed and reported from the top drilling type, in the tracking while drilling process, the horizontal well drilling of the horizontal reservoir stratum is relatively easy to judge and track, but the target horizon which is inclined and thin is relatively difficult to obtain, the well track is usually drilled from the top of the reservoir stratum or from the bottom of the reservoir stratum, the drilling track is drilled from the bottom of the reservoir stratum, the operation is easy in the implementation process, the geological risk is small, and various parameters are relatively simple and convenient to obtain; and the track is drilled from the top of the reservoir, so that the type is less analyzed and evaluated at home and abroad, and a corresponding theoretical calculation model is lacked.
In summary, at present, there is no calculation method for apparent thickness and true thickness in forward and reverse drilling of inclined reservoir horizontal well trajectory, and a reasonable application range.
Disclosure of Invention
The invention aims to solve the problems, provide a while-drilling geosteering method for inclining a horizontal well track in a thin reservoir, solve the problem of low drilling encountering rate of a horizontal section oil layer in a forward reservoir and a reverse reservoir, provide early warning for horizontal well drilling in advance by effectively evaluating the apparent thickness and the true thickness in the drilling process, and provide feasible technical support for efficient development of new and old oil fields.
The invention realizes the aim through the following technical scheme, and a while-drilling geosteering method for inclining a horizontal well track in a thin reservoir comprises the following steps:
step A: basic data analysis, and collection, sorting and analysis of earthquake, geological, well logging, well drilling and production data;
and B: calculating the apparent thickness and the true thickness of the forward reservoir;
and C: calculating the apparent thickness and the true thickness of the reverse reservoir;
step D: and main measures are taken for reservoirs with different tendencies to ensure normal drilling of the horizontal well.
Preferably, in step B, the apparent thickness and the true thickness in the consequent reservoir are calculated according to a formula;
forward reservoir drilling:
the forward reservoir drilling is a type commonly adopted in the horizontal well drilling process, if the variation of azimuth angles is not considered, theta is a reservoir inclination angle, and h is1Altitude depth of landing site, h2Altitude of the point of formation, h is the true thickness of the reservoir, hVisionFor drilling the apparent thickness of the reservoir, hOVertical reservoir thickness, hZIs the actual depth of the drill bit in the reservoir; Δ L is the variation of the horizontal displacement of the track, usually the difference between the horizontal displacement of the landing point and the horizontal displacement of the exit point (D)1B1Or D2B2) (ii) a Forward reservoir drilling hVisionH, assuming the angle of the well is considered to be(β) remaining unchanged, the greater the horizontal displacement or the length of the drilling trajectory in the horizontal section (h' primarily refers to AB1And AB2) The longer, the apparent thickness (AD)1And AD2) The larger the error with the true thickness of the reservoir, the more the depth of the well drilled in the forward reservoir increases, the more gradually the apparent thickness of the well increases;
①, forward reservoir bottom drilling type
Drilling a type reservoir from the bottom of the forward reservoir according to the thickness, and solving (h) by using the length of a drilling track in a horizontal sectionVisionH' cos β), or hOIn the known case, the apparent thickness (h) is determined by the change in the horizontal displacementVision＝hO+ΔLtgθ)；
②, forward reservoir top-drilling type
The drill bit drills out from the top or the upper part of the reservoir, so that the horizontal well cannot drill to reach the geological purpose, the drill bit drills in parallel along a certain depth of the top of the reservoir after entering a landing point A, a large error exists between the drilling depth obtained by a conventional algorithm and the actual drilling depth in the reservoir, and when the drill bit drills to a position B1At the point, the thickness of the reservoir after the conventional log sag correction is hOThe bit is mistakenly considered to be drilled to the bottom of the reservoir, and the increase of the deflection must be started, so that the bit is drilled from the upper part of the reservoir, and if the well deflection angle β is not changed, the ADB is a right-angled triangle, and the calculation formula h is adopted according to the thicknessVisionH' cos β and hVisionΔ L tg θ; in the vertical thickness of hOIn the process, the calculation formula of the true thickness of the reservoir is h ≈ h' cos theta cos β, and the calculation formula of the drill bit at any point of the drill bit can adopt a bottom drilling type calculation formula.
Preferably, in step C, the apparent thickness and the true thickness in the reverse reservoir are calculated according to a formula;
reverse reservoir drilling:
reverse reservoir drilling is a special type of horizontal well, the main parameters of which are similar to those of a forward reservoir, and the drilling method is characterized in that when the well inclination angle β is more than 90 degrees, the elevation depth of a target stratum point is drilled to be less than the elevation depth (h) of a landing point2＜h1) The well-logging result map obtained by conventional algorithm and its correctionVertical thickness does not represent true reservoir thickness, the greater the horizontal displacement (Δ L) or the length of the drilling trajectory within the horizontal section (h' refers primarily to AB1And AB2) The longer, the apparent thickness (AD)1、AD2、AD3) The greater the error from the true thickness of the reservoir;
① reverse reservoir bottom drilling type
The length of the horizontal section of the horizontal well drilled from the bottom of the reservoir cannot reach the geological purpose, the reservoir of the type is obtained according to the different thicknesses of β and the change of the horizontal displacement, and when β is less than 90 degrees, h is obtainedVision＝hO- Δ Ltg θ, when β is 90 °, hVision0, when β is greater than 90 DEG, hVision＝ΔLtg(β-θ)；
Actual depth h of drill bit in reservoirZThe calculation is related to the size of β angle, when β is less than 90 degrees, hZH-h' tg θ tg (β - θ), when β is 90 °, hZWhen β is greater than 90 deg., drilling the vertical line from target layer point to A point, and finding hZH' sin (β -90 °), the larger the angle β, hZThe larger, assume hZNear the true thickness of the reservoir section, the drill bit will drill out from the top of the target zone;
② reverse reservoir top drilling type
The type is also a special type drilled from the bottom of a reservoir, when β is less than or equal to 90 degrees plus theta, the reservoir is supposed to have great error in the depth of drilling in the reservoir according to the thickness calculation principle and the actual drilling depth in the reservoir under the condition that a drill bit is close to parallel drilling along the fixed depth of the top of the reservoir after entering an A landing point, and delta AE is supposed to1B1Is a right triangle, then the formula h can be usedVisionH' sin (β -90 °) or hVisionObtaining the true thickness position h of any point in the reservoir by the value of delta Ltg (β -90 DEG)ZCan pass through hZH-h' cos θ sin (β -90 °) or hZThe formula h- Δ Ltg (β -90 °) is obtained.
Preferably, the step D: taking the main countermeasures against differently inclined reservoirs comprises the following steps: a forward reservoir:
1) the type of the oil reservoir far away from the edge bottom water is preferred so as to ensure the oil reservoir development effect;
2) building a forward reservoir top or bottom drilling model diagram, and accurately measuring and calculating a reservoir inclination angle;
3) the window entry oblique angle is selected to be about (90-theta-3 degrees), the oblique angle is too small to easily drill through an oil layer, the oblique angle is too large to enter the window, and the requirements of drilling and well completion construction are met; in the horizontal section drilling process, the well inclination angle is also reasonably controlled, the drill bit is guaranteed to keep drilling at the well inclination angle of (90-theta) in the forward reservoir, and the apparent thickness and the true thickness of the reservoir are conveniently obtained;
4) determining the position of the bit in the reservoir, how much to increase the bias or when to take the bias, depending on the position of the bit in the reservoir, h can be found whenever the top or bottom hole is drilledZThe position of (a);
5) the bottom drill-out type from the target reservoir is usually taken to counter the reservoir apparent thickness to be close to hOWhen the track approaches B1Gradually taking inclination increasing measures;
reverse reservoir:
1) the edge-bottom water reservoir type or the oil-water interface inclined reservoir is optimized, so that the potential of residual oil can be better excavated and submerged;
2) building a reverse reservoir top or bottom drilling model diagram, and accurately measuring and calculating a reservoir inclination angle;
3) the recommended window well inclination angle is selected to be about (90 degrees + theta-3 degrees), and the actual depth h of a drill bit in a reservoir stratum is obtained in the process of drilling when the horizontal well lands to the horizontal sectionZThe inclination angle and h should be kept from large to small and then from small to largeZMutual authentication;
4) in the process of increasing or reducing the inclination of the reverse reservoir, the dog leg is prevented from being too large, so that the stable operation of subsequent construction is ensured.
The invention has the beneficial effects that: according to the method, four theoretical calculation models are formed by drilling from the top or the bottom of a drill bit in a forward reservoir and a reverse reservoir possibly, 16 calculation formulas are formed for the apparent thickness and the true thickness in the drilling process of a horizontal well in the forward reservoir and the reverse reservoir, the method for the horizontal well trajectory while drilling geosteering in the inclined thin reservoir is proposed and established, different adjustment countermeasures are proposed by means of the fact that the 16 formulas for calculating the apparent thickness and the true thickness in the reservoirs with different tendencies are different from the use range of the formulas, and the drilling rate of the oil layer in the horizontal section is guaranteed. The method can fully utilize geological, logging and well drilling information in the development block, has the characteristics of comprehensive consideration, simplicity in operation and better accordance with actual conditions, can ensure effective drilling of the horizontal well, and provides technical support for oil and gas exploration and development.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a diagram of a drilling pattern in a forward reservoir of a drilling trajectory;
FIG. 3 is a diagram of a drilling trajectory from a reverse reservoir drilling pattern.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, a method for geosteering while drilling a horizontal well trajectory in a deviated thin reservoir includes the following steps:
step A: basic data analysis, and collection, sorting and analysis of earthquake, geological, well logging, well drilling and production data;
the geological data, seismic data, logging data and production data, 8 models, namely a reservoir comparison model, a structural model of a target layer, a reservoir distribution model, an interlayer distribution model, an oil sand body distribution model, a fluid property distribution model, an oil reservoir pressure distribution model and a residual oil distribution model, need to be established no matter in a new region or an old region by utilizing the basic data of the region, and the geological design of the horizontal well is developed on the basis.
And B: calculating the apparent thickness and the true thickness of the forward reservoir;
forward reservoir drilling:
the forward reservoir drilling isThe type is often adopted in the horizontal well drilling process, if the variation of azimuth angle is not considered, the theta is the reservoir inclination angle and h is shown in figure 21Altitude depth of landing site, h2Altitude of the point of formation, h is the true thickness of the reservoir, hVisionFor drilling the apparent thickness of the reservoir, hoVertical reservoir thickness, hzIs the actual depth of the drill bit in the reservoir; Δ L is the variation of the horizontal displacement of the track, usually the difference between the horizontal displacement of the landing point and the horizontal displacement of the exit point (D)1B1Or D2B2) (ii) a Forward reservoir drilling hVisionH, assuming the angle of inclination (β) is held constant, the greater the horizontal displacement or the length of the drilling trajectory within the horizontal segment (h' refers primarily to AB)1And AB2) The longer, the apparent thickness (AD)1And AD2) The greater the error from the true thickness of the reservoir, the greater the depth the well drilled in the forward reservoir will be as the apparent thickness increases.
①, forward reservoir bottom drilling type
Forward reservoir drilling from the bottom type reservoir apparent thickness is usually determined by the length of the drilling trajectory within the horizontal section (h)VisionH' cos β), or hOIn the known case, the apparent thickness (h) is determined by the change in the horizontal displacementVision＝hO+ Δ Ltg θ) is shown in table 1; in FIG. 2(a), the thickness of the reservoir (as the thickness is considered) in the output log graph according to the conventional algorithm is obviously larger than the real thickness of the reservoir, if the correction or the measure is not carried out in time, the reservoir is mistakenly considered to be thickened, the drilling is still carried out along the oblique angle of the original well, and the reservoir is easily drilled from the bottom; the bit is at the true thickness position (h) at any point in the reservoirZ) The determination is very important, and can be according to B in FIG. 2(a)1A perpendicular line from the point to the AC is calculated as B1Depth of point in reservoir, hZH' cos (β + θ), when drilling to B2Real thickness h-h of point-time reservoirZ。
②, forward reservoir top-drilling type
The drill bit drills out from the top or upper part of the reservoir, generally the horizontal well drilling cannot reach the geological purpose, and the conventional algorithm is adopted on the assumption that the drill bit drills in parallel along a certain depth of the top of the reservoir after entering the landing point AThe obtained drilling depth has a large error with the actual drilling depth in the reservoir when the drilling reaches B1At the point, the thickness (apparent thickness) of the reservoir after the conventional log sag correction is hOIn the method, the drill bit is mistakenly considered to be drilled to the bottom of the reservoir, the increase of the deflection is started, so that the drill bit is drilled from the upper part of the reservoir, the drill bit is always kept at the top of the reservoir at a fixed depth in the step (b) in FIG. 2, similar errors are common in actual drilling, however, the drill-following pilots usually do not realize the severity of the problem, a proper method is not found, errors caused in the drilling process are avoided, and if the deflection angle β is not changed, the Delta ADB is a right triangle, and a calculation formula (h) is adopted according to the thickness in the step (H) in Table 1)VisionH' cos β and hVisionΔ Ltg θ); in the vertical thickness of hoIn the process, the calculation formula of the true thickness of the reservoir is h ≈ h' cos theta cos β, and the calculation formula of the drill bit at any point of the drill bit can adopt a bottom drilling type calculation formula.
Table 1 shows the evaluation table of the apparent thickness and the true thickness in drilling of the inclined reservoir
In step C), the apparent thickness and the true thickness in the reverse reservoir are calculated according to a formula.
Reverse reservoir drilling:
reverse reservoir drilling is a special type of horizontal well, the main parameters of which are similar to those of a forward reservoir, and is characterized in that when the inclination angle β is more than 90 degrees, the elevation depth of a target layer point drilled in the figure 3 is less than the elevation depth (h) of a landing point2＜h1) The vertical thickness of the log result graph obtained by the conventional algorithm does not represent the real thickness of the reservoir, and the larger the horizontal displacement (delta L) or the length of the drilling track in the horizontal section (h' mainly refers to AB)1And AB2) The longer, the apparent thickness (AD)1、AD2、AD3) The larger the error from the true thickness of the reservoir.
① reverse reservoir bottom drilling type
Horizontal well drilled from the bottom of reservoir and having horizontal section length not reaching geological purposeThe reservoir of the type is obtained by utilizing the change of horizontal displacement according to the difference of β in terms of thickness (see table 1), and when β is less than 90 degrees, h isVision＝hO- Δ Ltg θ, when β is 90 °, hVision0, when β is greater than 90 DEG, hVisionThe apparent thickness (corrected sag thickness of the conventional log plot) changes at the position of a point in fig. 3, and the apparent thickness obtained from the point a upwards occupies the thickness of the overlying reservoir, and the corrected sag thickness of the conventional log plot becomes smaller and smaller as the horizontal displacement of the conventional log plot is longer.
The true thickness position h at any point in the reservoir in FIG. 3(a)ZThe calculation is related to the angle β, when β < 90 ° (see table 1), hZH-h' tg θ tg (β - θ), when β is 90 °, hZWhen β is greater than 90 deg., drawing perpendicular line from the vertical line of target layer point to A point position in FIG. 3(a) to obtain hZH' sin (β -90 °), the larger the angle β, hZThe larger, assume hZNear the true thickness of the reservoir section, drill-out of the drill bit from the top of the destination layer occurs.
② reverse reservoir top drilling type
This type is also a special type drilled from the bottom of the reservoir (see Table 1), when β ≦ 90 ° + θ, assuming in FIG. 3(b) that the drill bit approaches parallel drilling at a fixed depth along the top of the reservoir after entering the A landing, this type of reservoir has a large error in determining the dominant thickness from the actual drilling depth in the reservoir, assuming in FIG. 3(b) that Δ AE is assumed1B1Is a right triangle, then the formula h can be usedVisionH' sin (β -90 °) or hVisionDetermining the true thickness position h of any point in the reservoir in the graph of FIG. 3(b)ZCan pass through hZH-h' cos θ s + n (β -90 °) or hZH- Δ Ltg (β -90 °) formula (see table 1)
In the step B, apparent thickness and true thickness calculation and error analysis in the forward reservoir
In the field drilling practice of the forward reservoir, if the actual thickness of the reservoir is 5 meters, the well inclination angle is 84 degrees and the reservoir inclination angle is 5 degrees in the figure 2(b), and the length of a drill bit track in the reservoir reaches 47.8 meters, the conventional logging is performed by adopting h for correcting the verticalityVisionH' cos βThe apparent thickness is close to 5 meters, the drill bit is usually misjudged to drill to the bottom of the reservoir at the moment and is close to the drilled reservoir, and h is utilized at the momentZThe actual depth of the drill bit in the reservoir is 0.83 m, if the deflection is adjusted according to the thickness, the drill bit quickly drills out a target layer, so that the drilling rate of the effective reservoir is low, if the horizontal section length is 100 m, the conventional vertical correction thickness is 10.45 m, the drill bit is estimated to enter 2.1 times the depth of the reservoir with the actual thickness, the actual drilling track is drilled only at the upper 1.74 m of the reservoir, and the difference often overturns the normal geological understanding.
In the step C: calculating apparent thickness and true thickness of reverse reservoir and analyzing error
In the field drilling of the reverse reservoir, if the real thickness of the reservoir is 5 meters, the well inclination angle is 94 degrees and the reverse reservoir inclination angle is 5 degrees in the figure 3(b), and the length of a drill bit track in the reservoir reaches 71.6 meters, the conventional logging is adopted for correcting the sag by hVisionWhen the apparent thickness is close to 5 meters, the logging verticality correction section shows that the thickness of the upper-lying reservoir layer lacks the corresponding thickness, the drill bit is mistakenly considered to drill to the bottom of the reservoir layer, and h is utilizedZThe h-h' cos θ sin (β -90) equation finds the actual depth of the bit in the reservoir to be 0.024 meters, and once the deflection is increased, the formation of interest is drilled.
In the step D: taking primary countermeasures against differently inclined reservoirs
A forward reservoir:
1) the type of reservoir far from the bottom water is preferred in order to ensure the reservoir development effect.
2) Building a drilling model diagram at the top or the bottom of a forward reservoir, accurately measuring and calculating the inclination angle of the reservoir,
3) the window entry oblique angle is selected to be about (90-theta-3 degrees), the oblique angle is too small to easily drill through an oil layer, the oblique angle is too large to enter the window, and the requirements of drilling and well completion construction are met; in the horizontal section drilling process, the well inclination angle is also reasonably controlled, the drill bit is guaranteed to keep drilling at the well inclination angle of (90-theta) in the forward reservoir, and the apparent thickness and the true thickness of the reservoir are conveniently obtained.
4) Determining the location of the bit in the reservoir, how much to increase the bias, or when to take the bias, depending on the bit locationAt locations in the reservoir, whether top or bottom drilled, h can be foundZThe position of (a); if the drill bit drills to B in FIG. 2(B)1B2In between, a segmented prediction mode can be adopted, namely B1The point approximation is considered as a landing point, and the position of the drill bit in the reservoir is presumed in a corresponding manner to the point A.
5) The bottom drill-out type from the target reservoir is usually taken to counter the reservoir apparent thickness to be close to hoWhen the track approaches B1Gradually taking inclination increasing measures; when the drill bit is drilled from the top of the reservoir and the position of the drill bit in the reservoir is determined, as shown in fig. 2(b), appropriate inclination reduction measures are adopted, so that the horizontal section length and the drilling effect of the horizontal well can be guaranteed.
Reverse reservoir:
1) the edge-bottom water reservoir type or the oil-water interface inclined reservoir is optimized, so that the potential of residual oil can be better excavated and submerged;
2) establishing a reverse reservoir top or bottom drilling model diagram, accurately measuring and calculating the reservoir inclination angle,
3) the inclination angle of the well with the recommended entry window is selected to be about (90 degrees + theta-3 degrees), and the true thickness position h of any point of the horizontal well is selected in the drilling process from landing to horizontal sectionzThe inclination angle and h should be kept from large to small and then from small to largezMutual authentication;
4) in the process of increasing or reducing the inclination of the reverse reservoir, the dog leg is prevented from being too large, so that the stable operation of subsequent construction is ensured.
In recent years, in Dagang oil fields, horizontal well field tracking research is carried out on partial oil reservoirs of Chengjiang sea, Sanmu sheep and northern Dagang successively, so as to form an idea and a method based on field work, earthquake, geology and field drilling tools are organically combined, four modes and a calculation method are drilled from the bottom and the top of a reservoir layer by utilizing drill bit tracks in a forward reservoir layer and a reverse reservoir layer, early warning is carried out in advance, main countermeasures adopted by horizontal section geosteering are worked out aiming at different reservoir layer types, the method is simple and applicable, reduces complicated and complicated work head threads of field tracking, ensures effective drilling of the horizontal well, particularly since 2010, 19 horizontal wells are successfully implemented by applying the method, the one-time window entry success rate of the horizontal well is 100%, the average oil layer drilling rate is 92%, and the drilling success rate and the oil layer drilling rate are greatly improved.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (2)
1. A geological guiding method while drilling for a horizontal well track in an inclined thin reservoir is characterized in that: the method comprises the following steps:
step A: basic data analysis, and collection, sorting and analysis of earthquake, geological, well logging, well drilling and production data;
and B: calculating the apparent thickness and the true thickness of the forward reservoir;
and C: calculating the apparent thickness and the true thickness of the reverse reservoir;
step D: main measures are taken for reservoirs with different tendencies to ensure normal drilling of the horizontal well;
in the step B, calculating the apparent thickness and the true thickness of the forward reservoir according to a formula;
forward reservoir drilling:
forward reservoir drilling is a type commonly adopted in the drilling process of horizontal wells, the type does not consider the change of azimuth angles, theta is a reservoir inclination angle, and h is1Altitude depth of landing site, h2Altitude of the point of formation, h is the true thickness of the reservoir, hVisionFor drilling the apparent thickness of the reservoir, hoVertical reservoir thickness, hZIs the actual depth of the drill bit in the reservoir; Δ L is a change amount of the horizontal displacement of the trajectory, which is a difference between the horizontal displacement of the exit point and the horizontal displacement of the landing point; forward reservoir drilling hVisionIf the inclination angle β is considered to be kept unchanged, the larger the horizontal displacement or the longer the drilling track length in the horizontal section is, the larger the error between the apparent thickness and the reservoir true thickness is, and the apparent thickness of the well drilled in the forward reservoir is gradually increased along with the increase of the depth;
①, forward reservoir bottom drilling type
Drilling a type reservoir from the bottom of the forward reservoir according to the thickness of the reservoir, and solving h by using the length of a drilling track in a horizontal sectionVisionH' cos β, or hOIn the known case, the apparent thickness h is determined by the change in the horizontal displacementVision＝hO+ Δ Ltg θ, where h' refers to the drilling trajectory length within the horizontal segment;
②, forward reservoir top-drilling type
The drill bit drills out from the top or the upper part of the reservoir, the horizontal well cannot achieve the geological purpose, the drill bit drills in parallel along a certain depth of the top of the reservoir after entering the landing point A, a large error exists between the drilling depth obtained by a conventional algorithm and the actual drilling depth in the reservoir, and when the drill bit drills to a certain position, the thickness of the reservoir after the conventional logging diagram is corrected to sag is hOThe drill bit is mistakenly considered to be drilled to the bottom of the reservoir, the increase of the deflection is started, so that the drill bit is drilled from the upper part of the reservoir, and the calculation formula h is adopted according to the thicknessVisionH' cos β or hVisionΔ Ltg θ; in the vertical thickness of hoIn the process, the calculation formula of the true thickness of the reservoir is h ≈ h' cos theta cos β, and the calculation formula of the drill bit at any point of the drill bit adopts a bottom drilling type calculation formula;
in the step C, calculating the apparent thickness and the true thickness in the reverse reservoir according to a formula;
reverse reservoir drilling:
the reverse reservoir drilling is a special type of horizontal well, the main parameters are similar to those of a forward reservoir, and the reverse reservoir drilling is characterized in that when the inclination angle β is more than 90 degrees, the elevation depth of a drilled target layer point is less than the elevation depth of a landing point, a logging result graph obtained by a conventional algorithm is adopted, the corrected vertical thickness does not represent the real thickness of the reservoir, the larger the Delta L is, the longer the drilling track length in a horizontal section is, and the larger the error between the apparent thickness and the real thickness of the reservoir is;
① reverse reservoir bottom drilling type
The length of the horizontal section of the horizontal well drilled from the bottom of the reservoir cannot reach the geological purpose, the reservoir of the type is obtained according to the different thicknesses of β and the change of the horizontal displacement, and when β is less than 90 degrees, h is obtainedVision＝hO- Δ Ltg θ, when β is 90 °, hVision0, when β is greater than 90 DEG, hVision＝ΔLtg(β-θ)；
Actual depth h of drill bit in reservoirZThe calculation is related to the size of β angle, when β is less than 90 degrees, hZH-h' tg θ tg (β - θ), when β is 90 °, hz0, β > 90 DEG, hZH' sin (β -90 °), the larger the angle β, hZThe larger, assume hZNear the true thickness of the reservoir section, the drill bit will drill out from the top of the target zone;
② reverse reservoir top drilling type
This type is also a special type drilled from the bottom of the reservoir, using the formula h when β > 90VisionH' sin (β -90 °) or hVisionH is obtained by determining Δ Ltg (β -90 °)ZThrough hZH-h' cos θ sin (β -90 °) or hZThe formula h- Δ Ltg (β -90 °) is obtained.
2. The geosteering while drilling method for sloping horizontal well trajectories in thin reservoirs as claimed in claim 1, wherein: the step D: taking the main countermeasures against differently inclined reservoirs comprises the following steps: a forward reservoir:
1) selecting the type of the oil reservoir far away from the edge bottom water so as to ensure the oil reservoir development effect;
2) building a forward reservoir top or bottom drilling model diagram, and accurately measuring and calculating a reservoir inclination angle;
3) the window entry well inclination angle is selected to be (90-theta-3 degrees), the well inclination angle is too small to easily drill through an oil layer, the well inclination angle is too large to enter the window, and meanwhile, the requirements of well drilling and well completion construction are met; in the horizontal section drilling process, the well inclination angle is also reasonably controlled, the drill bit is guaranteed to keep drilling at the well inclination angle of (90-theta) in the forward reservoir, and the apparent thickness and the true thickness of the reservoir are conveniently obtained;
4) determining the location of the bit in the reservoir, how much to increase the bias or when to take the bias, depending on the location of the bit in the reservoir, the location of hZ can be found whenever the top or bottom hole is drilled;
5) the countermeasure taken for the type drilled from the bottom of the reservoir is that the apparent thickness of the reservoir is close to hOGradually taking inclination increasing measures;
reverse reservoir:
1) the edge-bottom water reservoir type or the oil-water interface inclined reservoir is selected, so that the potential of residual oil can be better excavated and submerged;
2) building a reverse reservoir top or bottom drilling model diagram, and accurately measuring and calculating a reservoir inclination angle;
3) the window well inclination angle is selected to be (90 degrees + theta-3 degrees), and the actual depth h of a drill bit in a reservoir layer is realized in the process of drilling when the horizontal well lands to the horizontal sectionZThe inclination angle and h should be kept from large to small and then from small to largeZMutual authentication;
4) in the process of increasing or reducing the inclination of the reverse reservoir, the dog leg is prevented from being too large, so that the stable operation of subsequent construction is ensured.
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| CN113534244A (en) * | 2020-04-14 | 2021-10-22 | 中国石油天然气集团有限公司 | Method and device for determining thickness of reservoir plumb when drilling well meets reservoir |
| CN111472756B (en) * | 2020-05-28 | 2023-06-30 | 中国石油天然气集团有限公司 | Calculation method for safety well bevel angle of horizontal well deflecting section |
| CN112377104B (en) * | 2020-10-30 | 2023-04-07 | 中国石油天然气集团有限公司 | Method and device for dynamically adjusting actual drilling track of tight sandstone gas reservoir horizontal well |
| CN115217446B (en) * | 2021-04-21 | 2024-03-29 | 中石化石油工程技术服务有限公司 | Resource exploitation method and device |
| CN113700475A (en) * | 2021-07-28 | 2021-11-26 | 中石化石油工程技术服务有限公司 | Micro-amplitude structure logging while-drilling identification method and device, storage medium and electronic equipment |
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