CN110185439A - A kind of well is interior without coiled tubing down-hole pressure analogy method under gas condition - Google Patents

Abstract

The invention discloses a coiled tubing downhole pressure simulation method under the condition of no gas in the well, comprising the following steps: S1: calculating the volume V _in of the mud flowing into the wellbore from the pump; S2: calculating the volume V _out of the mud flowing out of the pump; S3: calculating the total volume of the mud in the wellbore V′; S4: Calculation of the expansion coefficient K of the whole well in the wellbore; S5: Calculation of the expansion pressure P _expansion of the whole well; S6: Calculation of the hydrostatic column pressure P of the tubing and casing and P _{casing static} ; S7: Comparing the P _{oil static} and the size of the P _sleeve ; if the P _oil pressure is greater than the P _sleeve pressure, the tubing pressure P _oil = P _expansion , and the casing pressure P _sleeve = P _expansion - (P _oil pressure - P _sleeve pressure); if the P _oil pressure is less than P If the _{casing is static} , the tubing pressure P _oil = P _expansion - (P _{oil static} - P _{sleeve static} ), the casing pressure P _sleeve = P _expansion ; S8: add circulating pressure to the oil pressure, and cycle the above steps, the present invention The method is beneficial to improve the simulation system's simulation degree of coiled tubing operation parameters.

Description

A simulation method for coiled tubing downhole pressure under the condition of no gas in the well

technical field

The invention relates to the field of coiled tubing downhole pressure measurement and calculation, in particular to a coiled tubing downhole pressure simulation method under the condition of no gas in the well.

Background technique

In order to enhance the proficiency of operators who have just participated in oilfield work, simulation training technology is usually used to simulate the actual construction environment. Losses caused by mistakes during on-site operations.

Therefore, the degree of restoration of the simulation system to the real environment affects the quality of simulation training. When it comes to parameter changes, accurate measurement methods are conducive to improving the accuracy of model building.

Contents of the invention

In order to solve the above problems, the present invention proposes a coiled tubing downhole pressure simulation method under the condition of no gas in the well, comprising the following steps:

S1: Calculate the volume V _in of the mud flowing into the wellbore from the pump;

S2: Calculate the outflow mud volume V _out ;

S3: Calculate the total volume of mud in the wellbore V';

S4: Calculate the expansion coefficient K of the whole well in the wellbore;

S5: Calculate the expansion pressure P _expansion of the whole well;

S6: Calculate the hydrostatic column pressure P _{oil static} and P _{sleeve static} of the tubing and casing;

S7: Compare the size of the P casing and the P _casing ; if the P casing _is greater than the P _casing , then the _tubing pressure P _oil = P _expansion , and the _casing pressure P _casing = P _expansion - (P P casing - P _casing ); If P _oil pressure is less than P _sleeve pressure, oil pipe pressure P _oil = P _expansion - (P _oil pressure - P _sleeve pressure), casing pressure P _sleeve = P _expansion ;

S8: Add circulation pressure to the oil pressure, and repeat the above steps.

Further, the calculation method of the outflow mud volume V _out is Among them, S is the flow area, _Δp is the pressure difference between front and back, and ρ is the medium density. The applicable medium of this formula is liquid. If it is gas, it needs to be multiplied by the flow resistance coefficient C _d ; Mud volume V _out + wellbore volume V; expansion coefficient K=V′/V-1; expansion pressure _Pexpansion =K*H, H is wellbore depth.

The beneficial effects of the present invention are: a method for simulating downhole pressure of coiled tubing under the condition of no gas in the well is proposed, which is conducive to improving the simulation degree of the simulation system for coiled tubing operation parameters.

Description of drawings

Fig. 1 is a flow chart of the downhole pressure measurement and calculation method of coiled tubing under the condition of no gas in the well;

Figure 2 is a schematic diagram of the pressure inside the tubing when there is no gas in the well;

Figure 3 is a schematic diagram of pressure changes in the well.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a coiled tubing downhole pressure simulation method under the condition of no gas in the well includes the following steps:

S1: Calculate the volume V _in of the mud flowing into the wellbore from the pump;

S2: Calculate the outflow mud volume V _out ;

S3: Calculate the total volume of mud in the wellbore V';

S4: Calculate the expansion coefficient K of the whole well in the wellbore;

S5: Calculate the expansion pressure P _expansion of the whole well;

S6: Calculate the hydrostatic column pressure P _{oil static} and P _{sleeve static} of the tubing and casing;

S7: Compare the size of the P casing and the P _casing ; if the P casing _is greater than the P _casing , then the _tubing pressure P _oil = P _expansion , and the _casing pressure P _casing = P _expansion - (P P casing - P _casing ); If P _oil pressure is less than P _sleeve pressure, oil pipe pressure P _oil = P _expansion - (P _oil pressure - P _sleeve pressure), casing pressure P _sleeve = P _expansion ;

S8: Add circulation pressure to the oil pressure, and repeat the above steps.

P _{oil static} = ρg h; ρ—liquid density in oil pipe; g—gravity acceleration; h—liquid depth in oil pipe;

P _{sleeve static} = ρg h; ρ—liquid density in the casing; g—gravitational acceleration; h—liquid depth in the casing.

As shown in Figure 2, tubing pressure is also called standpipe pressure, that is, vertical pressure. When there is no gas in the oil and gas well, the pressure is generated by the liquid column. In the case of no flow in the well, pump pressure = vertical pressure, bottom hole pressure = Standing pressure + standpipe static pressure, bottom hole pressure = casing pressure + casing static pressure. At the initial stage of shutting down the well and starting the pump, because the pressure in the well is lower than the maximum pressure of the pump, fluid still flows into the well, resulting in an increase in the volume of the fluid in the well. Due to the elasticity of the steel sleeve, the sleeve expands slightly and the pressure rises proportional to the pumped volume. In gas-free wells, the influence of the throttle valve on the casing pressure actually works together with the mud pump.

Therefore, the calculation method of the outflow mud volume V _out is Among them, S is the flow area, _Δp is the pressure difference between front and back, and ρ is the medium density. The applicable medium of this formula is liquid. If it is gas, it needs to be multiplied by the flow resistance coefficient C _d ; Mud volume V _out + wellbore volume V; expansion coefficient K=V′/V-1; expansion pressure _Pexpansion =K*H, H is wellbore depth.

As shown in Fig. 3, when the flow area S of the choke valve decreases, in order to keep V _out constant, the P _sleeve will rise. Since some fluid stays in the well, the volume in the well will be insufficient, and the wellbore will expand, causing the pressure in the well to rise.

The above disclosures are only preferred embodiments of the present invention, and certainly cannot limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims (5)

1. without coiled tubing down-hole pressure analogy method under gas condition in a kind of well, which comprises the following steps:

S1: it calculates pump and flows into well mud volume V_in；

S2: outflow mud volume V is calculated_out；

S3: mud total volume V ' in pit shaft is calculated；

S4: full well coefficient of expansion K in pit shaft is calculated；

S5: full well turgor pressure P is calculated_Expansion；

S6: the liquid column hydrostatic pressure P of oil pipe and casing is calculated_{Oil is quiet}And P_{It covers quiet}；

S7: compare P_{Oil is quiet}And P_{It covers quiet}Size；If P_{Oil is quiet}Greater than P_{It covers quiet}, then tubing pressure P_Oil=P_Expansion, casing pressure P_Set=P_Expansion- (P_{Oil is quiet}-P_{It covers quiet})；If P_{Oil is quiet}Less than P_{It covers quiet}, then tubing pressure P_Oil=P_Expansion-(P_{Oil is quiet}-P_{It covers quiet}), casing pressure P_Set=P_Expansion；

S8: plus circulation pressure on oil pressure, the above steps are repeated.

2. without coiled tubing down-hole pressure analogy method, feature under gas condition in a kind of well according to claim 1 It is, the outflow mud volume V_outCalculation isWherein S is circulation area, and Δ p is front and back Pressure difference, ρ are Media density, this formula Applicable media is liquid, need to be multiplied by flow resistance coefficient C if gas_d。

3. without coiled tubing down-hole pressure analogy method, feature under gas condition in a kind of well according to claim 1 It is, the mud total volume V '=inflow well mud volume V_inFlow out mud volume V_out+ wellbore volume V.

4. without coiled tubing down-hole pressure analogy method, feature under gas condition in a kind of well according to claim 1 It is, the coefficient of expansion K=V '/V-1.

5. without coiled tubing down-hole pressure analogy method, feature under gas condition in a kind of well according to claim 1 It is, the turgor pressure P_Expansion=K*H, H are mine shaft depth.