CN103790568B - A kind of drilling parameter and efficiency real-time optimization method - Google Patents

Abstract

The invention discloses a method for real-time optimization of drilling parameters and efficiency. Firstly, drilling and coring is carried out, and a rock strength model is established by using the method in step A. According to the density and properties of the drilling fluid and the pore pressure of the formation, it is judged which drilling method is used. If it is gas drilling, the uniaxial compressive strength can be directly used; otherwise, the rock strength under confining pressure at the bottom hole is calculated, and the mechanical specific energy of the drill bit is calculated using the mud logging data, and the calculated mechanical specific energy of the drill bit is compared with the rock under confining pressure at the bottom hole. strength for comparison. The model established by the invention can find out the critical failure points of drilling parameters such as drilling pressure and rotating speed, and can achieve the purpose of optimizing drilling parameters in real time, so that the drilling capacity can be effectively improved on the basis of existing drilling.

Description

A method for real-time optimization of drilling parameters and efficiency

technical field

The invention relates to a drilling optimization method, in particular to a real-time optimization method of drilling parameters and efficiency.

Background technique

The drilling optimization methods in the prior art are all established based on overbalanced drilling. There are many problems in drilling optimization for gas drilling and underbalanced drilling. Even the optimization for underbalanced drilling is based on the overbalanced drilling optimization model. It cannot be used in the three drilling methods of gas drilling, underbalanced drilling and overbalanced drilling at the same time.

Contents of the invention

In order to overcome the defects in the prior art, the present invention provides a method for real-time optimization of drilling parameters and efficiency that can be used in three drilling modes: gas drilling, underbalanced drilling, and overbalanced drilling. The method established by the present invention is based on rock Based on the re-establishment of the strength model, the present invention proposes a new model for calculating the rock strength at the bottom of the well. The established model can find out the critical failure points of drilling parameters such as drilling pressure and rotational speed, and can optimize drilling parameters in real time. The purpose is to effectively improve the drilling capacity on the basis of existing drilling.

Its technical scheme is as follows:

A method for real-time optimization of drilling parameters and efficiency, characterized in that it comprises the following steps:

A. Establishment of rock strength calculation model:

A1 collect rock cores with different porosities for a certain type of rock, and measure the porosity of the collected rock cores;

A2 Carry out triaxial rock mechanics experiments on rock cores with different porosities, and measure the compressive strength of rocks under different confining pressures;

A3 uses the particle swarm optimization algorithm to determine the parameters (a, b, c) in the intensity model:

σ ₁ -σ ₃ ＝UCS ₀ (1+aσ ₃ ^b )×exp(-φ×c)

where σ ₁ is the triaxial compressive strength of the rock, σ ₃ is the test confining pressure, UCS ₀ is the uniaxial compressive strength of the rock at zero porosity, a, b, c are the model coefficients,

B calculates the bottom hole confining pressure, using the double effective stress principle to calculate the bottom hole confining pressure, and its model is:

σ ₃ ＝P _h -φ _c P _p

In the formula, P _h is the hydrostatic column pressure, P _p is the pore pressure, φ _c is the rock contact porosity, φ _c is greater than the effective porosity φ of the body, and less than 1, and the intermediate value between φ and 1 is taken for general rocks,

Then, the calculation model of bottomhole confining pressure strength can be expressed as:

σ ₁ -σ ₃ ＝UCS ₀ (1+a(P _h -φP _p ) ^b )×exp(-φ×c)

C Calculate the mechanical specific energy of the drill bit for rock breaking, the formula is:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.35</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 13.33</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span>$

In the formula, W is the weight on bit, A _b is the area of the drill bit, d _b is the diameter of the drill bit, μ is the coefficient of sliding friction, N is the rotational speed, ROP is the mechanical speed of penetration,

D First conduct drilling and coring, use the method in step A to establish a rock strength model, and judge which drilling method is used according to the drilling fluid density, properties and formation pore pressure. If it is gas drilling, you can directly use uniaxial compression Otherwise, use the first formula in step B to calculate the bottom hole confining pressure, use the second formula to calculate the rock strength under the bottom hole confining pressure, use the logging data to calculate the mechanical specific energy of the drill bit, and compare the calculated mechanical specific energy of the drill bit with The bottom hole confining pressure strength is compared. If the mechanical specific energy is continuously smaller than the bottom hole confining pressure strength value, continue drilling. If the parameters of WOB and RPM are ineffective, it is judged whether there are drilling accidents at the bottom of the well, such as mud balling, sticking, and serious wear of the drill bit, and the accidents are dealt with until the mechanical specific energy of the drill bit is less than the confining pressure strength value of the rock bottom.

Further preferably, if during the drilling process, the rock strength at the bottom of the hole does not change significantly, but the ROP gradually decreases, the mechanical specific energy gradually increases, the rotary table torque gradually increases, and at the same time, the pump pressure rises, then it is judged to be drill mud. Packing phenomenon occurs; if the ROP gradually decreases, the mechanical specific energy gradually increases, the rotary table torque and pump pressure do not change significantly, and the ROP does not improve significantly after adjusting the WOB and rotating speed, it is judged that the drill bit is severely worn; if the ROP If there is a sudden drop, the torque of the turntable rises suddenly, and the lifting and lowering of the drilling tool is blocked, it is judged that the drill is stuck.

Beneficial effects of the present invention: the method provided by the present invention and the established mathematical model can more accurately determine the specific reasons that lead to the reduction of ROP, can guide on-site construction to take correct methods to deal with drilling accidents in time, and improve drilling efficiency.

Description of drawings

Fig. 1 is the flow chart of drilling parameter and efficiency real-time optimization method of the present invention;

Fig. 2 is a comparison curve of rock confining pressure strength, mechanical specific energy, actual penetration rate, and drilling operation parameters in overbalanced drilling, where Fig. 2A is a curve of bottomhole rock confining pressure strength, mechanical specific energy, and actual penetration rate; Drilling operation parameter curve;

Figure 3 is a comparison chart of rock confining pressure strength, mechanical specific energy, and actual drilling speed in underbalanced drilling;

Fig. 4 shows operating parameters of underbalanced drilling;

Figure 5 is a comparison curve of rock strength, mechanical specific energy, actual penetration rate, and drilling operation parameters in gas drilling, where Figure 5A is a curve of bottomhole rock confining pressure strength, mechanical specific energy, and actual drilling rate, and Figure 5B is a drilling operation parameter curve.

detailed description

The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Fig. 1, a method for real-time optimization of drilling parameters and efficiency comprises the following steps:

The establishment of the calculation model of rock strength at the bottom of A:

A1 collect rock cores with different porosities for a certain type of rock, and measure the porosity of the collected rock cores;

A2 Carry out triaxial rock mechanics experiments on rock cores with different porosities, and measure the compressive strength of rocks under different confining pressures;

A3 uses the particle swarm optimization algorithm to determine the parameters (a, b, c) in the strength model:

σ ₁ -σ ₃ ＝UCS ₀ (1+aσ ₃ ^b )×exp(-φ×c)

where σ ₁ is the triaxial compressive strength of the rock, σ ₃ is the test confining pressure, UCS ₀ is the uniaxial compressive strength of the rock at zero porosity, a, b, c are the model coefficients,

B calculates the bottom hole confining pressure, using the double effective stress principle to calculate the bottom hole confining pressure, and its model is:

σ ₃ ＝P _h -φ _c P _p

In the formula, P _h is the hydrostatic column pressure, P _p is the pore pressure, φ _c is the rock contact porosity, φ _c is greater than the effective porosity φ of the body, and less than 1, and the intermediate value between φ and 1 is taken for general rocks,

Then, the calculation model of bottomhole confining pressure strength can be expressed as:

σ ₁ -σ ₃ ＝UCS ₀ (1+a(P _h -φP _p ) ^b )×exp(-φ×c)

C Calculate the mechanical specific energy of the drill bit for rock breaking, the formula is:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.35</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 13.33</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span>$

In the formula, W is the weight on bit, A _b is the area of the drill bit, d _b is the diameter of the drill bit, μ is the coefficient of sliding friction, N is the rotational speed, ROP is the mechanical speed of penetration,

D First conduct drilling and coring, use the method in step A to establish a rock strength model, and judge which drilling method is used according to the drilling fluid density, properties and formation pore pressure. If it is gas drilling, you can directly use uniaxial compression Otherwise, use the first formula in step B to calculate the bottom hole confining pressure, use the second formula to calculate the rock strength under the bottom hole confining pressure, use the logging data to calculate the mechanical specific energy of the drill bit, and compare the calculated mechanical specific energy of the drill bit with If the mechanical specific energy is lower than the rock bottom confining pressure value, continue drilling; if the mechanical specific energy is lower than the rock bottom confining pressure value, and adjusting the WOB and speed parameters has no effect, then Judging whether there are drilling accidents at the bottom of the well, such as bit balling, drill sticking, and severe bit wear, and handling the accidents until the mechanical specific energy of the bit is less than the confining pressure strength value of the rock bottom.

Further preferably, if the ROP gradually decreases, the mechanical specific energy gradually increases, and the turntable torque increases gradually, accompanied by an increase in the pump pressure, then it can be judged that the bit bagging phenomenon occurs; if the ROP gradually decreases, the mechanical specific energy Gradually increase, the torque of the turntable and the pump pressure have no obvious change, and the ROP has not improved significantly after adjusting the pressure on bit and rotating speed, it may be that the drill bit is severely worn; If resistance is encountered, it is judged that the pipe is stuck.

The method of the present invention is used to calculate the rock strength at the bottom of an overbalanced drilling well in a certain area and the mechanical specific energy of drilling. The formation pore pressure coefficient is: 1.0-1.3g/cm ³ , and the density of the drilling fluid used is 1.61g /cm ³ . The results are shown in _Fig . 2. When the drilling is above 3450 meters, the mechanical specific energy E _s is below the rock compressive strength line σ1. , increased the WOB, but this did not increase the ROP, but decreased, making the mechanical specific energy E _s line exceed the strength σ ₁ curve, which fully shows that the WOB W and the ROP ROP are not related. It shows a linear relationship. When the WOB exceeds the critical failure point, continuing to increase the WOB will not bring about an increase in the ROP. It can be seen that the established model can find out the critical failure points of drilling parameters such as pressure on bit and speed, and can achieve the purpose of optimizing drilling parameters in real time, so that the drilling capacity can be effectively improved on the basis of existing drilling.

Fig. 3 is an example of bottomhole calculation for an underbalanced drilling well. The formation pore pressure coefficient is 1.1-1.3g/cm ³ , and the drilling fluid density is 1.0g/cm ³ , the rock strength at the bottom hole and the mechanical specific energy of drilling are used. According to the calculation, it can be seen from the figure that with the increase of the well depth, the strength of the rock does not change much, but has a slight increase trend with the increase of the well depth, and there are two sharp increases in the mechanical specific energy in the figure (Fig. Points A and B in 3) correspond to a sharp drop in the ROP. The author found that this was mainly caused by improper operation of the parameters when consulting the well history data, as shown in Fig. 4. It can also be seen that the method is valid for identifying drilling parameters, therefore, the calculation model for the strength of rock at the bottom of the well established by the present invention is still valid for liquid underbalanced drilling.

The rock strength at the bottom of a gas drilling well and the mechanical specific energy of drilling were calculated using this method. The calculation results are shown in Fig. 5. It can be seen that the calculation method still shows a good description effect on gas drilling, as shown in Fig. 4 Although the WOB of 50KN was implemented in zone A, its ROP was between 5-10m/h, but in zone B in Fig. 3, the WOB dropped to 30KN, but its ROP increased to between 8-15m/h During the period, the critical failure point of drilling parameters still exists in gas drilling, therefore, the model established by the present invention shows good performance in describing the performance of gas drilling. Although gas drilling shows high efficiency of rock breaking and speed increase, if the drilling parameters are implemented reasonably, the speed increase effect will be even better.

The above is only a preferred specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention can obviously obtain the simplicity of the technical solution. Changes or equivalent replacements all fall within the protection scope of the present invention.

Claims (2)

1. A drilling parameter and efficiency real-time optimization method, is characterized in that, comprises the following steps: The establishment of the calculation model of rock strength at the bottom of A: A1 collect rock cores with different porosities for a certain type of rock, and measure the porosity of the collected rock cores; A2 Carry out triaxial rock mechanics experiments on rock cores with different porosities, and measure the compressive strength of rocks under different confining pressures; A3 uses the particle swarm optimization algorithm to determine the parameters (a, b, c) in the intensity model: σ ₁ -σ ₃ ＝UCS ₀ (1+aσ ₃ ^b )×exp(-φ×c) where σ ₁ is the triaxial compressive strength of the rock, σ ₃ is the test confining pressure, UCS ₀ is the uniaxial compressive strength of the rock at zero porosity, a, b, c are the model coefficients, B calculates the bottom hole confining pressure, using the double effective stress principle to calculate the bottom hole confining pressure, and its model is: σ ₃ ＝P _h -φ _c P _p In the formula, P _h is the hydrostatic column pressure, P _p is the pore pressure, φ _c is the rock contact porosity, φ _c is greater than the effective porosity φ of the body, and less than 1, and the intermediate value between φ and 1 is taken for general rocks, Then, the calculation model of bottomhole confining pressure strength can be expressed as: σ ₁ -σ ₃ ＝UCS ₀ (1+a(P _h -φP _p ) ^b )×exp(-φ×c) C Calculate the mechanical specific energy of the drill bit for rock breaking, the formula is: ${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.35</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 13.33</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span>$ In the formula, W is the weight on bit, A _b is the area of the drill bit, d _b is the diameter of the drill bit, μ is the coefficient of sliding friction, N is the rotational speed, ROP is the mechanical speed of penetration, D First conduct drilling and coring, use the method in step A to establish a rock strength model, and judge which drilling method is used according to the drilling fluid density, properties and formation pore pressure. If it is gas drilling, you can directly use uniaxial compression Otherwise, use the first formula in step B to calculate the bottom hole confining pressure, use the second formula to calculate the rock strength under the bottom hole confining pressure, use the logging data to calculate the mechanical specific energy of the drill bit, and compare the calculated mechanical specific energy of the drill bit with For comparison, if the mechanical specific energy is continuously lower than the rock bottom confining pressure value, continue drilling. If the mechanical specific energy is greater than the rock bottom confining pressure value, adjust the drilling pressure and speed parameters. If there is no effect, Then it is judged whether there are drilling accidents such as bit bagging, drill sticking and severe drill bit wear at the bottom of the well, and the accidents are dealt with until the mechanical specific energy of the drill bit is less than the confining pressure strength value of the rock bottom. 2. The real-time optimization method of drilling parameters and efficiency according to claim 1, characterized in that, if the ROP gradually decreases, the mechanical specific energy increases gradually, and the torque of the turntable increases gradually, accompanied by an increase in pump pressure, then it can be It is judged that the drill bit bagging phenomenon occurs; if the ROP gradually decreases, the mechanical specific energy gradually increases, the rotary table torque and pump pressure do not change significantly, and the ROP does not improve significantly after adjusting the drilling pressure and rotating speed, it may be that the drill bit is severely worn; If the ROP suddenly drops, the torque of the turntable rises suddenly, and the lifting and lowering of the drilling tool is blocked, it is judged that the drill is stuck.