CN105178869B - Method for calculating size combination of nozzle of drill bit for petroleum drilling - Google Patents

Abstract

The invention discloses a method for calculating size combination of nozzles of a drill bit for petroleum drilling; optimal solutions of di and ni are obtained according to constraint conditions; i is not smaller than 0; m is not smaller than i; a nozzle size nearest the optimal solutions is obtained; the constraint conditions are as follows: 1) di is not smaller than a1 and not greater than a2; and i is not smaller than 0 and not greater than m; 2) di+1-di is not smaller than 0 and not greater than bi; and i is not smaller than 1 and not greater than m; 3) the summation of ni equals to n with i ranging from 1 to m; 4) delta S=Sd-Sopt bigger than 0, wherein Sd and Sopt are described in the description, m and n represent that n nozzles have m sizes; di is the diameters of the nozzles with the ith size and is ranked according to that the diameter di is gradually reduced with the increment of i; ni is the number of the nozzles with the ith size; a1 and a2 are experience numerical values for limiting the nozzle size; bi is an experience numerical value for limiting the nozzle size difference; pd is the drilling liquid density; and pbd is the designed maximum pressure drop of the drill bit. The method can accurately and quickly obtain an optimal nozzle size combination.

Description

The jet size combination computational methods of oil drilling drill bit

Technical field

The present invention relates to oil drilling technology field, in particular to a kind of jet size of oil drilling drill bit Combination computational methods.

Background technology

Practice have shown that, in larger the pressure of the drill and the range of speeds, reducing nozzle diameter, increase jet jet velocity can show Write and improve rate of penetration and footage per bit.Crept into compared with normal drill bit using jet bit, the footage per bit in soft formation 50%～100% can be improved, 13%～28% can be then improved in hard formation；Rate of penetration can improve 15 in soft formation～ 30%, 14%～21% can be improved in hard formation.

For in theory, field engineer is needed according to the construction speed of institute's drilling well, drilling parameter, BHA and drilling well Situations such as equipment, determines the optimum capacity of drill bit and optimum nozzle equivalent diameter, and selects the jet size of drill bit to combine.However, In real work, affected by field apparatus ability, typically empirically determined first drilling fluid displacement, then according to brill Tool combination and mud property parameter calculate cyclic pressure dissipation, change jet size combination finally by continuous, it is ensured that bit nozzle pressure Drop presses consumption sum less than the rated pressure of drilling pump with circulation of drilling fluid.To save amount of calculation, and also to ensure to bore The rated pump pressure of well pump can meet normal drilling demand, and the ratio that the jet size combination that situ of drilling well is adopted often is selected is larger, The effect that bit hydraulic auxiliary rock ability and mitigation landwaste hold pressure effect is set greatly to weaken.

The content of the invention

The technical problem to be solved is, there is provided one kind can accurately and rapidly obtain optimum nozzle size The method of combination,

Therefore, technical scheme is as follows：

A kind of jet size combination computational methods of oil drilling drill bit, according to constraints Δ S minimums are tried to achieve Lower d_iAnd n_iOptimal solution, 1≤i≤m, then with the immediate jet size of the optimal solution, described constraints includes |：

1)a₁≤d_i≤a₂, 1≤i≤m；

2)0≤d_i+1-d_i≤b_i, 1≤i≤m-1；

3)

4) Δ S=S_d-S_opt>0, wherein,

Wherein, m and n represent in n nozzle altogether there is size in m, d_iDiameter for i-th kind of size nozzle and according to i Increase diameter increases successively sequence, n_iFor the quantity of i-th kind of size nozzle, a₁And a₂To limit the empirical value of jet size, b_i To limit the empirical value of nozzle member size difference, ρ_dFor drilling fluid density, p_bdThe maximum pressure for proposing meter for drill bit drops, and Q is Drilling fluid displacement, each Parameter units are d_i-mm、a₁-mm、a₂-mm、b_i-mm、ρ_d-g/cm³、b_i-mm、p_bd- MPa, Q-L/s.

In the technical scheme, can be according to nozzle quantity, the drilling well for creeping into live standby drill bit using instruments such as excel Liquid parameter, slush pump rated pressure and DHA and jet size constraints, quickly calculate optimum nozzle size Combination, so that under conditions of slush pump normal work is met, the waterpower auxiliary rock-breaking effect of drill bit is played to greatest extent.

Further, p_bd=p_bmax/ f, p_bmax=p_r-Δp_cs；Wherein, p_rFor drilling pump rated pump pressure, Δ p_csFollow for drilling well Loop systems pressure loss, f be according to experience setting safety coefficient, p_rWith Δ p_csUnit is MPa.

In the technical scheme, using p_rWith Δ p_csCalculate the maximum pressure drop p of drill bit_bmax, further with one Safety coefficient f determines final p_bd, it is contemplated that real pump pressure (actual pump pressure during mud pump work) of sending out can be low to a certain extent In rated pump pressure p_r, so as to ensure that it is relatively reliable that calculating is recorded a demerit.

Specific embodiment

It should be noted that in the case where not conflicting, the feature in embodiments herein and embodiment can be mutual Combination.

According to an embodiment of the invention the jet size combination computational methods of oil drilling drill bit, are used with certain well As a example by 21.59cm drill bits, nozzle number is 5, Φ 17.78/7.14cm drill collar 80m, and remaining is Φ 12.7/10.862cm drilling rods, Estimated the boring of the drill bit reaches well depth for 4000m, drilling fluid averag density 1.2g/cm³, plastic viscosity 20mPas, two NB8-600 Pump.Comprise the following steps that.

Step one, calculates cyclic pressure dissipation.By way of on-the-spot test, measure respectively inside and outside manifold of ground, drill collar and bore Cyclic pressure dissipation coefficient inside and outside bar, finally tries to achieve cyclic pressure dissipation for 7.77MPa.

Step 2, according to engineering practice minimum injection rate Q is determined_minFor 23.93L/s.

Step 3, according to pump physical condition cylinder sleeve diameter is selected.For NB8-600 pumps, according to《Drilling well handbook》There is provided Data, can select the cylinder sleeve of 130mm diameters, rated pump pressure is 19.6MPa, rush number for 65 times/min when rated discharge Q_rFor 15.34L/s, during using double pump, Q_rFor 30.68L/s.

Step 4, according to on-site actual situations drilling fluid displacement is determined.Determined most using maximum jet impact force principle Excellent discharge capacity is 30.76L/s, because gained optimum drilling fluid displacement is more than the rated discharge of slush pump, takes actual well drilled liquid discharge capacity Q Equal to the rated discharge of slush pump, i.e. 30.68L/s.

Step 5, calculates bit nozzle equivalent aera and diameter.In drilling process, drilling pump is in rated pump pressure work shape State, the sectional area S under bit nozzle equivalent diameter_JFor

The relation of the actual each nozzle diameter of nozzle equivalent diameter and drill bit is

Wherein, S_JFor the sectional area (mm under nozzle equivalent diameter²), d_tFor bit nozzle equivalent diameter (mm), Q is drilling well Liquid actual flow (L/s), P_sPump pressure (MPa) is sent out in fact for drilling pump takes rated pump pressure value (note：Real pump pressure of sending out refers to mud pump work When actual pump pressure, can to a certain extent be less than rated pump pressure, therefore the bit nozzle equivalent diameter calculated and area It is less than normal, thus before programming evaluation is carried out, need to set a safety coefficient, the cross-section area of nozzle and spray after appropriate increase optimization Outspoken footpath).

Obviously, in known preferred nozzle diameter d_tAfterwards, meeting n nozzle diameter of above formula has Multiple Combination form, and hand Work amount of calculation is big and is difficult to determine the bit hydraulic auxiliary rock effect concrete which kind of jet size combination can be best, explanation In a certain nozzle equivalent diameter d_tWith sectional area S_JUnder the conditions of, there are various solutions in jet size combination, and be difficult to judge optimum Solution.

Step 6, using programming evaluation instrument (such as Excel), addition solves constraints, calculates and obtains bit nozzle Optimum size combination.

p_bmax=P_s-Δp_cs=p_r-Δp_cs=19.6-7.77=11.83MPa

p_bd=p_bmax/ f=11.83/1.5=7.89MPa

S_d=π (n₁d₁ ²+n₂d₂ ²+n₃d₃ ²)/4

Δ S=S_d-S_opt

Solving constraints includes：

①For the scope of limits nozzle size, jet size scope can be according to the actual feelings of engineer applied Condition sets；

②For the difference size between limits nozzle size, can be according to engineer applied actual conditions Setting；；

③n₁, n₂, n₃0 integer is all greater than or equal to, for solving the number of different size nozzle；

④n₁+n₂+n₃=5, for limit solve draw nozzle sum it is identical with actual nozzle hole number on drill bit；

5. Δ S >=0, straight slightly larger than the optimum nozzle equivalent of drill bit for ensureing the Nozzle combination equivalent diameter that solution draws Footpath, so as to ensure to be within rated pump pressure during mud pump work.

Changing cell includes d₁, d₂, d₃, n₁, n₂, n₃, object element is Δ S.Solve changing cell under Δ S minimal conditions Value, show that qualified jet size is combined as the dimension combination as bit nozzle.

Using the programming evaluation function in Excel, arrange and solve object, after defined variable and constraint, try to achieve d₁=8mm, d₂ =8mm, d₃=9mm, n₁=0, n₂=2, n₃2, the nozzle of=3, i.e. 8mm, utilization drilling well that can be best during 3, the nozzle of 9mm Liquid hydrodynamic cleaning ability.

The last nozzle specification specified according to handbook, selects and the immediate jet sizes of 8mm and 9mm, i.e., 2, the nozzle of 8.73mm, 3, the nozzle of 9.53mm.

In sum, present disclosure is not limited in the above embodiments, and those skilled in the art can be Propose other embodiments within the technological guidance's thought of the present invention, but this embodiment be included in the scope of the present invention it It is interior.

Claims (2)

1. a kind of jet size of oil drilling drill bit combines computational methods, it is characterised in that try to achieve Δ S according to constraints D under minimum_iAnd n_iOptimal solution, then 1≤i≤m draw and the immediate jet size of the optimal solution, described pact Beam condition includes：

1)a₁≤d_i≤a₂, 1≤i≤m；

2)0≤d_i+1-d_i≤b_i, 1≤i≤m-1；

3)

4) Δ S=S_d-S_opt>0, wherein,

Wherein, m and n are represented m kind sizes, d in n nozzle altogether_iDiameter for i-th kind of size nozzle and according to straight with i increases Footpath increases successively sequence, n_iFor the quantity of i-th kind of size nozzle, a₁And a₂To limit the empirical value of jet size, b_iTo limit The empirical value of nozzle member size difference, ρ_dFor drilling fluid density, p_bdFor the maximum pressure drop that drill bit proposes meter, Q is drilling fluid Discharge capacity, each Parameter units are d_i-mm、a₁-mm、a₂-mm、b_i-mm、ρ_d-g/cm³、b_i-mm、p_bd- MPa, Q-L/s；Sopt is drill bit Optimum equivalent nozzle area, Sd be drill bit programming evaluation adopt nozzle equivalent aera.

2. the jet size of oil drilling drill bit according to claim 1 combines computational methods, it is characterised in that：

p_bd=p_bmax/ f, p_bmax=p_r-Δp_cs；

Wherein, p_rFor drilling pump rated pump pressure, Δ p_csFor drilling circulation system pressure losses, f is the safety according to experience setting Coefficient, p_rWith Δ p_csUnit is MPa.