CN103266889A - Method for predicting drillability grade values of rock in different drilling directions of shale stratum - Google Patents

Abstract

The invention relates to a method for predicting drillability grade values of rock in different drilling directions of a shale stratum. The method includes the following steps: drillability grade values and interval transit time of a shale sample in different drilling directions are measured; a relation model among the drillability grade values, the interval transit time and drilling angles is established; a relation model among the interval transit time in the different drilling directions of the shale sample and interval transit time and a drilling angle in the perpendicular bedding plane direction is established; a relation model among the drillability grade values of the shale sample in the different drilling directions and the interval transit time and the drilling angle in the perpendicular bedding plane direction is established; logging information is obtained, and the interval transit time in the perpendicular bedding plane direction is obtained through inversion; according to the relation model among the drillability grade values in the different drilling directions of the shale stratum and the interval transit time and the drilling angle in the perpendicular bedding plane direction, drillability grade values in different drilling directions of a shale stratum on site are determined. According to the method, the acoustic logging information can be used for directly predicting the drillability grade values of the rock in the different directions of the shale stratum.

Description

The method of the drillability of rock level value under the different drilling directions of prediction shale formation

Technical field

The invention belongs to subterranean resource drilling field of engineering technology, particularly, relate to a kind of method of predicting the drillability of rock level value under the different drilling directions of shale formation.

Background technology

Rock drillability can be used as bit type selection and instructs geological layer important evidence in the exploration and development process of oil gas field.From the middle of last century, scholars both domestic and external just are devoted to the research of the drillability of rock, determine that by the laboratory core experimental method stratum rock drillability level value extensively adopted by petroleum industry.The prediction rock drillability has very important meaning to raising deep-well rate of penetration, shortening drilling period, raising deep drilling level accurately.Along with the rise of shale gas, also do not propose at the experimental evaluation method of the drillability of rock on rational stratum, rammell.

Summary of the invention

For overcoming the defective of prior art, the invention provides a kind of method of predicting the drillability of rock level value under the different drilling directions of shale formation, utilize the acoustic logging data directly to predict drillability of rock level value under the different drilling directions of shale formation.

For achieving the above object, the present invention adopts following scheme:

A kind of method of predicting the drillability of rock level value under the different drilling directions of shale formation may further comprise the steps:

Step 1 is measured the shale sample in the drillability level value of different drilling directions;

Step 2 is measured the interval transit time of corresponding drilling direction nextpage rock sample product;

Step 3, set up the drillability level value of the different drilling directions of shale sample and counterparty to interval transit time, creep into the relational model of angle;

Step 4, set up the different drilling directions of shale sample interval transit time and vertical stratification face direction interval transit time, creep into the relational model between the angle;

Step 5, set up the drillability level value of the different drilling directions of shale sample and vertical stratification face direction interval transit time, creep into the relational model of angle;

Step 6 obtains the well-log information of on-the-spot shale, and Inversion Calculation obtains the interval transit time of shale vertical stratification face direction;

Step 7, according to the drillability level value of the different drilling directions of determined shale formation and the interval transit time of the shale vertical stratification face direction that the interval transit time of vertical stratification face direction, the relational model that creeps into angle and Inversion Calculation obtain, determine the drillability level value of the different drilling directions of described on-the-spot shale.

Useful technique effect of the present invention is: can utilize the acoustic logging data directly to predict drillability of rock level value under the different drilling directions of shale formation.Compare with conventional method, this invention is simple and convenient, has saved the down-hole cost of coring, and has reduced a large amount of measurements etc. and has repeated work.

Description of drawings

Fig. 1 is the method flow schematic diagram of the drillability of rock level value under the different drilling directions of prediction shale formation.

Fig. 2 is that the angle between rock core axis and the bed plane normal concerns schematic diagram.

Fig. 3 utilizes the acoustic logging data to ask for the flow chart of vertical shale bedding direction compressional wave time difference method.

The specific embodiment

As shown in Figure 1, the method for the drillability of rock level value under the different drilling directions of prediction shale formation may further comprise the steps:

Step 1 is measured the shale sample in the drillability level value of different drilling directions, and concrete grammar is as follows:

1) utilizes the machine of coring to take out diameter from monoblock shale sample and be 76.2mm, the length rock core for the different bedding directions of 50mm, use lathe flat two end face cars of rock core, the parallelism tolerance value of sample both ends of the surface is no more than 0.2mm, and rock core is put into baking box with 100 ℃ of temperature baking 24h;

2) the different bedding direction rock cores after will handling are put into drillability of rock measuring system successively, measure the drillability level value of different bedding direction rock cores respectively;

Drilling direction is the axial of shale sample, with the relationship consistency of angle shown in Figure 2.

Step 2 is measured the interval transit time of corresponding drilling direction nextpage rock sample product, and concrete grammar is as follows:

1) utilizes the machine of coring to take out diameter from above-mentioned shale rock core and be 25mm, the length rock core for 50mm, the bedding direction of each rock core is corresponding with the bedding direction of each rock core in the step 1, use lathe flat two section cars of rock core, again rock core is put into baking box with 100 ℃ of temperature baking 24h;

2) the different bedding direction rock cores after will handling are put into sound wave measuring system successively, measure the interval transit time of different bedding direction rock cores respectively;

Drillability of rock level value under the different drilling directions that above-mentioned steps 1,2 is measured, interval transit time experimental result are as shown in table 1 below:

Table 1

Drilling direction as shown in Figure 2, the vertical stratification direction be 0 the degree, the parallel bedding direction be 90 the degree.

Step 3, set up the drillability level value of the different drilling directions of shale sample and counterparty to interval transit time, creep into the relational model of angle; Concrete grammar is as follows:

To the interval transit time of the drillability level value of the different drilling directions of shale sample and corresponding drilling direction, creep into angle and carry out nonlinear regression analysis, set up following Mathematical Modeling:

(formula 1)

In the formula:

Drillability of rock level value under the different drilling directions; Interval transit time under the different drilling directions, unit (us/m);

The angle of rock core axis and bedding normal direction, unit (°).

Need to prove that each coefficient depends on the data of carrying out multiple regression, and not exclusive value.

Step 4, set up the different drilling directions of shale sample interval transit time and vertical stratification face direction interval transit time, creep into the relational model between the angle; Concrete grammar is as follows:

To the interval transit time of the interval transit time of the different bedding directions of shale sample and vertical stratification direction, creep into angle and carry out nonlinear regression analysis, set up following Mathematical Modeling:

(formula 2)

In the formula:

Interval transit time under the different drilling directions, unit (us/m);

The angle of rock core axis and bedding normal direction, unit (°);

Be the interval transit time of vertical stratification direction, unit (us/m).

Step 5, set up the drillability level value of the different drilling directions of shale sample and vertical stratification face direction interval transit time, creep into the relational model of angle, concrete grammar is as follows:

Formula 2 is brought in the formula 1, and it is as follows to obtain Mathematical Modeling:

(formula 3)

In the formula;

Drillability of rock level value under the different drilling directions;

The angle of rock core axis and bedding normal direction, unit (°);

Be the interval transit time of vertical stratification direction, unit (us/m).

Step 6 obtains the well-log information of on-the-spot shale, and Inversion Calculation obtains the interval transit time of shale vertical stratification face direction, and concrete grammar is as follows:

As shown in Figure 3, it is as follows to utilize well-log information to ask for vertical stratification direction interval transit time method,

Determine after the rock anisotropy parameter ε and δ of a certain well section, wherein

$\mathrm{\δ}=\frac{1}{{2C}_{33}^2}[2{(C_{13}+C_{44})}^2-(C_{33}-C_{44})(C_{11}+C_{33}-2C_{44})].$ In the formula, C _IjImplication abide by Hooke's law, be not described further at this.

At first calculate crowd angle φ according to attitude of stratum data and hole trajectory data _g

Next given one initial vertical stratification face direction velocity of longitudinal wave v _{P, 0},

$v_{\mathrm{SV},0}=\frac{v_{P,0}-1.36}{1.16}$ (formula 4)

v _{P, 0}Be vertical stratification face direction velocity of longitudinal wave, unit (km/s); v _{SV, 0}Be vertical stratification face direction shear wave velocity, unit (km/s).

Calculate shear wave velocity, determine ripple ratio in length and breadth.

Calculate phase angle again:

$\tan \mathrm{\θ}=\frac{\left\{2\right[M_3\left(\mathrm{\θ}\right)-M_2\left(\mathrm{\θ}\right){]\sin }^2\mathrm{\θ}-M_4\left(\mathrm{\θ}\right)\}\tan {\mathrm{\φ}}_g}{2[M_3\left(\mathrm{\θ}\right)-M_2\left(\mathrm{\θ}\right)-2M_1]{\sin }^2\mathrm{\θ}-M_4\left(\mathrm{\θ}\right)-2M_3\left(\mathrm{\θ}\right)}$ (formula 5)

Wherein, M ₁=ε ²-2t δ+2t ε; M ₂(θ)=4t δ+ε R (θ)-2t ε; M ₃(θ)=2t δ+ε R (θ)-t ε; M ₄(θ)=t ²-tR (θ)+2R (θ); $R\left(\mathrm{\θ}\right)={(4({\mathrm{\ϵ}}^2+2\mathrm{t\ϵ}-2\mathrm{t\δ}){\sin }^4\mathrm{\θ}+4t(2\mathrm{\δ}-\mathrm{\ϵ}){\sin }^2\mathrm{\θ}+t^2)}^{\frac{1}{2}}=2D\left(\mathrm{\θ}\right)+t$ $t=1-{\mathrm{\β}}_0^2/{\mathrm{\α}}_0^2.$ φ _gBe the group angle, unit (°); v _aBe phase velocity, unit (°); θ is phase angle, unit (°); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s); β ₀Be the shear wave velocity of vertical stratification face direction, unit (km/s).

Calculate phase velocity then,

$\frac{v_{\mathrm{Pa}}^2\left(\mathrm{\θ}\right)}{{\mathrm{\α}}_0^2}=1+\mathrm{\ϵ}{\sin }^2\mathrm{\θ}+D\left(\mathrm{\θ}\right)$ (formula 6)

Wherein $D\left(\mathrm{\θ}\right)=\frac{1}{2}\sqrt{4({\mathrm{\ϵ}}^2+2\mathrm{t\ϵ}-2\mathrm{t\δ}){\sin }^4\mathrm{\θ}+4t(2\mathrm{\δ}-\mathrm{\ϵ}){\sin }^2\mathrm{\θ}+t^2}-\frac{1}{2}t,$ v _PaBe the compressional wave phase velocity, unit (km/s); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s); θ is phase angle, unit (°).

Calculate group velocity:

$v_{\mathrm{Pg}}\left({\mathrm{\φ}}_g\left(\mathrm{\θ}\right)\right)=\frac{1}{v_{\mathrm{Pa}\left(\mathrm{\θ}\right)R\left(\mathrm{\θ}\right)}}{\{v_{\mathrm{Pa}}^4\left(\mathrm{\θ}\right)R^2\left(\mathrm{\θ}\right)+{\mathrm{\α}}_0^4{\sin }^2\mathrm{\θ}{\cos }^2\mathrm{\θ}{[2M_1{\sin }^2\mathrm{\θ}+M_3\left(\mathrm{\θ}\right)]}^2\}}^{\frac{1}{2}}$ (formula 7)

v _PgBe the compressional wave group velocity, unit (km/s); v _PaBe the compressional wave phase velocity, unit (km/s); θ is phase angle, unit (°); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s).

At last the velocity of wave of the group velocity that calculates and well-log information is compared, if both coincide, this v then _{P, 0}Being institute asks.If both differ bigger, then change v _{P, 0}Repeat above step till both match.

After obtaining the velocity of wave of vertical stratification face direction, can obtain the interval transit time of this direction

(formula 8)

Be vertical stratification face direction interval transit time, unit (us/m); v _{P, 0}Be vertical stratification face direction velocity of longitudinal wave, unit (km/s).

Step 7, according to the drillability level value of the different drilling directions of determined shale formation and the interval transit time of the shale vertical stratification face direction that the interval transit time of vertical stratification face direction, the relational model that creeps into angle and Inversion Calculation obtain, determine the drillability level value of the different drilling directions of described on-the-spot shale.Concrete grammar is as follows:

Bring the interval transit time of the on-the-spot shale vertical stratification face direction that obtains in the step 6 into drillability level value that formula 3 can obtain each drilling direction of shale formation.

Claims (8)

1. a method of predicting the drillability of rock level value under the different drilling directions of shale formation is characterized in that, may further comprise the steps:

Step 1 is measured the shale sample in the drillability level value of different drilling directions;

Step 2 is measured the interval transit time of corresponding drilling direction nextpage rock sample product;

Step 3, set up the drillability level value of the different drilling directions of shale sample and counterparty to interval transit time, creep into the relational model of angle;

Step 4, set up the different drilling directions of shale sample interval transit time and vertical stratification face direction interval transit time, creep into the relational model between the angle;

Step 5, set up the drillability level value of the different drilling directions of shale sample and vertical stratification face direction interval transit time, creep into the relational model of angle;

Step 6 obtains the well-log information of on-the-spot shale, and Inversion Calculation obtains the interval transit time of shale vertical stratification face direction;

Step 7, according to the drillability level value of the different drilling directions of determined shale formation and the interval transit time of the shale vertical stratification face direction that the interval transit time of vertical stratification face direction, the relational model that creeps into angle and Inversion Calculation obtain, determine the drillability level value of the different drilling directions of described on-the-spot shale.

2. the method for the drillability of rock level value under the different drilling directions of prediction shale formation according to claim 1 is characterized in that the concrete grammar of step 1 is as follows:

1) utilizes the machine of coring to take out diameter from monoblock shale sample and be 76.2mm, the length rock core for the different bedding directions of 50mm, use lathe flat two end face cars of rock core, the parallelism tolerance value of sample both ends of the surface is no more than 0.2mm, and rock core is put into baking box with 100 ℃ of temperature baking 24h;

2) the different bedding direction rock cores after will handling are put into drillability of rock measuring system successively, measure the drillability level value of different bedding direction rock cores respectively.

3. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-2, it is characterized in that the concrete grammar of step 2 is as follows:

1), utilizes the machine of coring to take out diameter from above-mentioned shale rock core and be 25mm, the length rock core for 50mm, the bedding direction of each rock core is corresponding with the bedding direction of each rock core in the step 1, use lathe flat two section cars of rock core, again rock core is put into baking box with 100 ℃ of temperature baking 24h;

2), the different bedding direction rock cores after will handling put into sound wave measuring system successively, measure the interval transit time of different bedding direction rock cores respectively.

4. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-3, it is characterized in that, the concrete grammar of step 3 is as follows: to the interval transit time of the drillability level value of the different drilling directions of shale sample and corresponding drilling direction, creep into angle and carry out nonlinear regression analysis, set up Mathematical Modeling.

5. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-4, it is characterized in that, the concrete grammar of step 4 is as follows: to the interval transit time of the interval transit time of the different bedding directions of shale sample and vertical stratification direction, creep into angle and carry out nonlinear regression analysis, set up Mathematical Modeling.

6. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-5, it is characterized in that the concrete grammar of step 5 is as follows: with step 4 gained Mathematical Modeling bring into the drillability level value that obtains the different drilling directions of shale sample in the step 3 gained Mathematical Modeling and vertical stratification face direction interval transit time, creep into the relational model of angle.

7. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-6, it is characterized in that it is as follows to utilize well-log information to ask for vertical stratification direction interval transit time method,

Determine after the rock anisotropy parameter ε and δ of a certain well section, wherein $\mathrm{\δ}=\frac{1}{{2C}_{33}^2}[2{(C_{13}+C_{44})}^2-(C_{33}-C_{44})(C_{11}+C_{33}-2C_{44})],$ In the formula, C _IjImplication abide by Hooke's law;

At first calculate crowd angle φ according to attitude of stratum data and hole trajectory data _g

Next given one initial vertical stratification face direction velocity of longitudinal wave v _{P, 0},

$v_{\mathrm{SV},0}=\frac{v_{P,0}-1.36}{1.16}$

v _{P, 0}Be vertical stratification face direction velocity of longitudinal wave, unit (km/s); v _{SV, 0}Be vertical stratification face direction shear wave velocity, unit (km/s);

Calculate shear wave velocity, determine ripple ratio in length and breadth;

Calculate phase angle again:

$\tan \mathrm{\θ}=\frac{\left\{2\right[M_3\left(\mathrm{\θ}\right)-M_2\left(\mathrm{\θ}\right){]\sin }^2\mathrm{\θ}-M_4\left(\mathrm{\θ}\right)\}\tan {\mathrm{\φ}}_g}{2[M_3\left(\mathrm{\θ}\right)-M_2\left(\mathrm{\θ}\right)-2M_1]{\sin }^2\mathrm{\θ}-M_4\left(\mathrm{\θ}\right)-2M_3\left(\mathrm{\θ}\right)}$

Wherein, M ₁=ε ²-2t δ+2t ε; M ₂(θ)=4t δ+ε R (θ)-2t ε; M ₃(θ)=2t δ+ε R (θ)-t ε; M ₄(θ)=t ²-tR (θ)+2R (θ); $R\left(\mathrm{\θ}\right)={(4({\mathrm{\ϵ}}^2+2\mathrm{t\ϵ}-2\mathrm{t\δ}){\sin }^4\mathrm{\θ}+4t(2\mathrm{\δ}-\mathrm{\ϵ}){\sin }^2\mathrm{\θ}+t^2)}^{\frac{1}{2}}=2D\left(\mathrm{\θ}\right)+t$ $t=1-{\mathrm{\β}}_0^2/{\mathrm{\α}}_0^2;$ φ _gBe the group angle, unit (°); v _aBe phase velocity, unit (°); θ is phase angle, unit (°); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s); β ₀Be the shear wave velocity of vertical stratification face direction, unit (km/s);

Calculate phase velocity then,

$\frac{v_{\mathrm{Pa}}^2\left(\mathrm{\θ}\right)}{{\mathrm{\α}}_0^2}=1+\mathrm{\ϵ}{\sin }^2\mathrm{\θ}+D\left(\mathrm{\θ}\right)$

Wherein $D\left(\mathrm{\θ}\right)=\frac{1}{2}\sqrt{4({\mathrm{\ϵ}}^2+2\mathrm{t\ϵ}-2\mathrm{t\δ}){\sin }^4\mathrm{\θ}+4t(2\mathrm{\δ}-\mathrm{\ϵ}){\sin }^2\mathrm{\θ}+t^2}-\frac{1}{2}t,$ v _PaBe the compressional wave phase velocity, unit (km/s); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s); θ is phase angle, unit (°);

Calculate group velocity:

$v_{\mathrm{Pg}}\left({\mathrm{\φ}}_g\left(\mathrm{\θ}\right)\right)=\frac{1}{v_{\mathrm{Pa}\left(\mathrm{\θ}\right)R\left(\mathrm{\θ}\right)}}{\{v_{\mathrm{Pa}}^4\left(\mathrm{\θ}\right)R^2\left(\mathrm{\θ}\right)+{\mathrm{\α}}_0^4{\sin }^2\mathrm{\θ}{\cos }^2\mathrm{\θ}{[2M_1{\sin }^2\mathrm{\θ}+M_3\left(\mathrm{\θ}\right)]}^2\}}^{\frac{1}{2}}$

v _PgBe the compressional wave group velocity, unit (km/s); v _PaBe the compressional wave phase velocity, unit (km/s); θ is phase angle, unit (°); α ₀Be the velocity of longitudinal wave of vertical stratification face direction, unit (km/s);

At last the velocity of wave of the group velocity that calculates and well-log information is compared, if both coincide, this v then _{P, 0}Being institute asks; If both differ bigger, then change v _{P, 0}Repeat above step till both match;

After obtaining the velocity of wave of vertical stratification face direction, can obtain the interval transit time of this direction

8. according to the method for the drillability of rock level value under the different drilling directions of the described prediction shale formation of claim 1-7, it is characterized in that the concrete grammar of step 7 is as follows: the Mathematical Modeling of bringing the interval transit time of the vertical stratification face direction that obtains in the step 6 into step 4 gained can obtain the drillability level value of each drilling direction of shale formation.

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