CN104849762A - Method for correcting oil reservoir top surface micro structure by using information of horizontal well stratum penetrating point - Google Patents

Abstract

The invention relates to a technology for calculating a horizontal well oil reservoir development stratum true dip angle so as to correct an oil reservoir top surface micro structure, and particularly relates to a method for correcting the oil reservoir top surface micro structure by using information of a horizontal well stratum penetrating point. The method comprises the steps of determining the length of a delay interval by using delayed response characteristics of a natural gamma-ray logging curve when penetrating through a sand shale boundary, deducing and calculating a more accurate calculation method for a stratum true dip angle of the horizontal well stratum penetrating point by being combined with a well drilling inclination angle and an azimuth angle explained in the logging process, drawing a stratum dip angle plane graph, correcting the horizontal well oil reservoir top surface micro structure by taking the stratum dip angle plane graph as a basis, drawing a contour map with the spacing being less than 2m, and guiding reasonable development of an oil reservoir and potential tapping of residual oil. The method provided by the invention overcomes limitations in carrying out correction on the top surface micro structure by only using well point altitude and seismic data at present, provides a method for correcting horizontal well oil reservoir development top surface micro structure, makes full use of the information of the horizontal well stratum penetrating point, and acquires the true stratum dip angle, thereby studying the oil reservoir top surface micro structure more accurately.

Description

A Method of Correcting Reservoir Top Surface Microstructure Using Horizontal Well Penetration Point Information

technical field

The invention relates to a method for calculating the true dip angle of a reservoir for horizontal well development and correcting the microstructure of the top surface of the reservoir by using the true dip angle distribution map.

Background technique

Microstructure refers to the structural features shown by the fine fluctuations of the oil layer itself on the general reservoir structural background, with low uplifts and depressions, small closed areas, no certain directionality, irregular shapes, and irregular distribution. Therefore, it is difficult to find the local microstructure without more detailed research. The practice of oilfield development shows that the shape and amplitude of the microstructure directly affect the waterflooding development of the reservoir and the distribution of remaining oil, which is of great significance to the rational development of the reservoir and the tapping of the remaining oil potential in the later stage.

At present, the research on oil layer microstructure is mainly carried out with the help of denser well pattern drilling data, 3D seismic data and sub-layer fine correlation results. There are roughly two specific research methods: one is based on relatively dense well pattern data, combined with Combining well logging data, taking the top or bottom of the main sand layer as the standard, using small interval contours and interpolation contours to draw structural maps; the second is to use 3D seismic or high-resolution 3D seismic data and logging data Combined study of reservoir microstructure. Both of the above two traditional research methods have certain limitations. The first method only uses well point elevation data for correction, lacks the control of formation dip and dip, and it is difficult to accurately characterize the transitional shape of microstructures between wells; the second method The limitation lies in the accuracy of the original seismic data. If the accuracy of seismic data cannot meet the requirements of microstructure research, this work will be difficult to carry out.

Contents of the invention

The purpose of the present invention is to overcome the current limitation of only using well point elevation and seismic data for top surface microstructure correction, and to provide an accurate, practical and easy-to-spread method for top surface microstructure correction.

In order to achieve the above object, the specific technical solution adopted by the present invention is: the method for correcting the microstructure of the top surface of the oil reservoir using the information of the entry point of the horizontal well, comprising the following steps:

Step 1: Using the relationship between the delay response characteristics of the natural gamma ray logging curve passing through the sand-shale interface and the rock layer, based on the gamma ray logging curve data, determine the length of the delay interval and clarify the gap between the well layers. Step 2: Combine the drilling inclination angle and azimuth angle explained in the logging process, and use the well point elevation data to derive and calculate the more accurate true dip angle of the horizontal well entry point. The calculation formula can be divided into two types Condition:

1. When the horizontal well penetrates along the formation dip:

(1) Calculate the formation apparent dip angle α _a

apparent inclination ${\mathrm{\α}}_a=\frac{\mathrm{\π}}{2}-\mathrm{\θ}-\mathrm{\γ}$

Where: γ is the angle between the tangent line of the entry point trajectory of the horizontal well and the formation, that is, the angle between well layers, rad;

The calculation formula is r is the detection depth of natural gamma ray logging tool, m; L is half of the delay response distance, m;

(2) Obtain the included angle ω of apparent inclination

Included angle of apparent inclination ω=β _s -β _w

Where: β _s is the formation dip azimuth, rad;

β _w is the azimuth angle of the well trajectory at the entry point, rad;

(3) Calculation of true formation dip α _t

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$

In the formula:

θ is the well trajectory inclination angle, rad;

r is the detection depth of natural gamma ray logging tool, m;

L is half of the delay response distance, m;

β _s is the formation dip azimuth, rad;

β _w is the azimuth angle of the well trajectory at the entry point, rad;

2. When the horizontal well penetrates against the formation inclination:

(1) Calculate the formation apparent dip angle α _a

apparent inclination ${\mathrm{\&alpha;}}_a=\mathrm{\&theta;}+\mathrm{\&gamma;}-\frac{\mathrm{\&pi;}}{2}$

(2) The calculation method of the apparent angle of the true dip is the same as the calculation method when the horizontal well penetrates along the stratum dip;

(3) Calculation of the true dip angle of the formation

According to the calculation method of the true dip of the formation when the horizontal well penetrates along the formation dip, combined with the calculation formula of the apparent dip when the horizontal well penetrates against the dip of the formation, the formula for calculating the true dip of the formation in this case can be written as:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$

Step 3: Drawing and Utilization of Stratum Dip Plane

According to the formula for calculating the true dip angle of the formation, the data such as the effective value and average value of the true dip angle of the horizontal well entry point in the oilfield can be counted. At this time, one well can read the information of multiple entry points. Based on this, the geological modeling interpolation method can be used to draw a plane distribution map of stratum dip angle with high precision; based on the drawn high-precision stratum dip plane map, correct The height of the stratum relief at the entry point of the horizontal well, and at the same time correct the structure beside the horizontal well, and obtain the microstructural map of the top surface of the sand layer with a spacing of 2m that can be used to guide production.

Different from traditional research methods that only use well point elevation data and seismic data, the method of the present invention utilizes the relationship between the delay response characteristics and rock layers when the natural gamma ray logging curve crosses the sand-shale interface, and uses gamma ray to measure Based on the well curve data, the length of the delay interval is determined, and the angle between the well layers is clarified; at the same time, combined with the drilling inclination angle and azimuth angle explained in the logging process, and using the well point elevation data, a comparative Accurately determine the true dip angle of the formation at the entry point of the horizontal well, and make statistics on its effective value, average value and other data, draw a plane map of the formation dip angle, and use this as a basis to correct the microstructure of the top surface of the horizontal well reservoir, and the drawing distance is less than The 2m contour map guides the rational development of reservoirs and taps the remaining oil potential.

Description of drawings:

Fig. 1 is the flow chart of the method for correcting the microstructure of the top surface of the oil reservoir using the information of the entry point of the horizontal well in the present invention;

Fig. 2 is the situation when the horizontal well trajectory penetrates along the stratum dip;

Fig. 3 is the situation when the horizontal well trajectory penetrates against the stratum dip;

Fig. 4 is a diagram of the method for calculating the angle between the well layers at the entry point using the delay response characteristics of the natural gamma ray curve, and the calculation formula for the angle between the well layers can be obtained according to the triangular relationship in the graph;

Fig. 5 is a diagram of the calculation method of the stratum dip angle, and XY in the figure is the stratum dip line.

Detailed ways

The method for correcting the microstructure of the top surface of the reservoir by using the information of the entry point of the horizontal well according to the present invention will be described in detail below with reference to the accompanying drawings.

Case 1: When a horizontal well penetrates along the formation dip

1. Calculate the true dip angle α _t of the formation

(1) Calculate the formation apparent dip angle α _a

First, according to the delay response characteristics of the natural gamma ray curve when it passes through the sand-shale interface, the delay distance is directly read on the comprehensive logging map, and half of it is recorded as L; then, the detection depth of the horizontal well natural gamma ray logging curve is established Statistical diagram (or use the average detection depth) to obtain the detection depth r of the gamma logging tool; then, from the triangular relationship diagram shown in Figure 4, calculate the angle between the tangent line of the horizontal well entry point trajectory and the formation γ, that is, the angle between well layers Finally, according to the read inclination angle θ of the well trajectory at the entry point, the calculation formula for the apparent inclination angle of the entry point of the horizontal well is established: in the rectangular plane ABDE (the rectangular plane formed by the tangent line of the well trajectory at the entry point of the horizontal well and the horizontal line), In the right angle ∠EAB, the apparent inclination As shown in Figure 2.

(2) Obtain the included angle ω of the true inclination

As shown in Figure 5, the elevation value of the horizontal well in the oil field is measured first, and the method of surface determination by three points is used to select the elevation of the entry point of 3 (or more than 3) wells to simply determine an approximate top surface; Then, draw the intersection line between the horizontal plane and the structural plane, and project this line onto the horizontal plane to calculate the dip azimuth angle β _s of the formation; finally, according to the azimuth angle β _w of the well trajectory at the entry point, determine the apparent dip angle Angle ω=β _s −β _w .

(3) Calculation of true formation dip α _t

By using the relationship between the corners and angles of the right triangles ABD, ABC and BCD, combined with the apparent dip angle α _a of the formation, the true dip angle of the formation can be obtained indirectly (as shown in Figure 2), and the specific calculation process is as follows:

In RtΔABD: AB=BD·tan(α _a )

In RtΔBCD: BC=BD·cos(ω)

It can be concluded that:

In RtΔABC:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; AB</span>}}{\mathrm{<span\; class="notranslate">\; BD</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; )</span>}$

(Where: AB is the vertical line of the entry point of the horizontal well, BC is the true dip line of the formation, and BD is the apparent dip line of the formation)

Substituting the above parameters, the general formula is:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$

In the formula:

θ is the well trajectory inclination angle, rad;

r is the detection depth of natural gamma ray logging tool, m;

L is half of the delay response distance, m;

β _s is the formation dip azimuth, rad;

β _w is the azimuth angle of the well trajectory at the entry point, rad;

2. Drawing of stratum dip plane

According to the formula for calculating the true dip angle of the formation, the data such as the effective value and the average value of the true dip angle of the formation at the entry point of the horizontal well in the oilfield can be counted. When the thickness of the oil layer is relatively thin, most horizontal wells in the oil field may frequently penetrate the top and bottom of the oil layer. At this time, one well can read the information of multiple entry points. High-precision planar distribution map of formation dip.

3. Use the drawn stratum dip plane distribution map

Based on the drawn high-precision stratum dip plane map, the stratum relief height of the entry point of the horizontal well is corrected, and the structure beside the well is corrected to obtain a microstructural map of the top of the sand layer with a spacing of 2m that can be used to guide production. It provides help for the implementation of water injection development strategy in the next step of the reservoir and the search for remaining oil-enriched areas.

Case 2: When the horizontal well penetrates against the formation dip

1. Calculate the true dip angle α _t of the formation

(1) Calculate the formation apparent dip angle α _a

According to the calculation method of the formation dip angle when the horizontal well penetrates along the formation dip, combined with the angle relationship shown in Figure 3 and Figure 4, the apparent dip angle when the horizontal well penetrates the formation against the formation dip can be obtained ${\mathrm{\&alpha;}}_a=\mathrm{\&theta;}+\mathrm{\&gamma;}-\frac{\mathrm{\&pi;}}{2}$

(2) The calculation method of the included angle of apparent true inclination is the same as the calculation method of Case 1

(3) Calculation of the true dip angle of the formation

According to the calculation method of true formation dip angle in case 1, combined with the calculation formula of apparent dip angle when a horizontal well penetrates against the formation dip, the calculation formula of true formation dip angle in case 2 can be written as:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$

The method of drawing the stratum dip plane map and using the drawn stratum dip plane distribution map is the same as the operation in case 1, and will not be repeated here.

Claims (1)

1. utilize horizontal well to enter a layer method for dot information correction oil reservoir end face micro-structure, comprise the following steps:

Step one: utilize Natural Gamma-ray Logging Curves through the relation delayed response feature during sand-shale boundary and face, rock stratum, based on GR logging curve data, determines to postpone burst length, specifies the angle between well layer; Step 2: in conjunction with the drilling well pitch angle of explaining in well logging and position angle, and utilize well point height above sea level data, deriving and calculating comparatively accurate horizontal well enters layer point stratum main dip, and this computing formula can be divided into two kinds of situations:

(1) when, horizontal well penetrates along dip direction:

(1) apparent formation dip α is calculated _a

Apparent dip

Wherein: γ is the angle that horizontal well enters layer between locus of points tangent line and stratum, i.e. well layer angle, rad;

Computing formula is (r is the investigation depth of natural gamma logging device, m; L is the half of delayed response distance, m; )

(2) ask for and look true tendency angle ω

Depending on true tendency angle ω=β _s-β _w

Wherein: β _sfor dip direction position angle, rad;

β _wfor entering layer point well track position angle, rad;

(3) stratum main dip α is calculated _t

In formula:

θ is well track pitch angle, rad;

R is the investigation depth of natural gamma logging device, m;

L is the half of delayed response distance, m;

β _sfor dip direction position angle, rad;

β _wfor entering layer point well track position angle, rad;

(2) when, horizontal well penetrates against dip direction:

(1) apparent formation dip α is calculated _a

Apparent dip

(2) computing method when penetrating along dip direction with horizontal well depending on true tendency angle acquiring method are identical;

(3) stratum main dip is asked for

Stratum main dip acquiring method when penetrating along dip direction according to horizontal well, apparent dip computing formula when Bound moisture horizontal well penetrates against dip direction, the stratum main dip computing formula of this situation can be written as:

Step 3: the drafting of stratigraphic dip planimetric map and utilization

According to stratum main dip computing formula, the data such as effective value, mean value that horizontal well in oil field enters layer point stratum main dip can be added up, when core intersection is relatively thin, in oil field, most horizontal well frequently may pass bottom surface, oil reservoir top, now, a bite well can read multiple enter layer dot information, based on this, utilize Geologic modeling interpolation method, the stratigraphic dip flat distribution map that precision is higher can be drawn; Based on the planimetric map of inclination layer accurately drawn, revise the stratum relief height that horizontal well enters layer point, the other structure of Horizontal Well is corrected simultaneously, obtain the layer of sand end face micro-structure figure of the 2m spacing that can be used for Instructing manufacture.