Well control is one of the important issues because improper well control will lead to a blowout which is the most feared operational hazard and expensive cost. For this study, the project focused on well control in ERD well using Halliburton's software, WELLPLAN. WELLPAN is very useful software which provides various functionalities such as torque-resistance analysis, analyze hydraulics, analyze surge/swab pressure and ECDs, investigate well control and etc.
The well control module can be used to determine predicted kick type, estimate inflow volume and kick tolerance, evaluate pressure and generate kill sheets. To remove the gas from the horizontal section, the kill rate must be 1/3 to ½ the rate of the drilling circulation flow rate. ERD = Extended Reach Drilling TVD = True Vertical Depth, ft HD = Horizontal Depth, ft MD = Measured Depth, ft ROP = Penetration Rate BOP = Blow-out Preventer CP = Circulating Pressure, psi ICP = Initial Circulating Pressure, psi FCP = Final Circulating Pressure, psi SPR = System pressure loss at kill rate, psi MW = Mud weight, ppg.
ECD = Equivalent Circulating Density, ppg SIDPP = Shutoff Pipe Pressure, psi SICP = Closed Case Pressure, psi Q = Flow Rate, gpm. Pdph = Hydrostatic drill pipe pressure, psi Pah = Annular-hydrostatic pressure, psi Pi = Flux-hydrostatic pressure, psi.
INTRODUCTION
- Project Background
- Problem Statement
- Objective
- Scope of Study
A blowout can occur when well control systems fail to control the flow of fluids from the formation. If the well control system could not detect the shock (formation pressure is higher than the wellbore pressure) and immediately and properly destroy the shock, a blowout will occur. One example is the accumulated and trapped gas shocks (gas buoyancy) at the well end if that section is inclined up.
Additionally, kill procedures in conventional wells are typically performed at a pump speed between 1/3 and ½ of the normal drilling rate. The scope of work involved in this project is the WELLPLAN software simulation related to well control in the laboratory. The Well Control Analysis module in WELLPLAN provides investigated control, determination of predicted stroke type and; estimate flux volume and stroke tolerance.
The student must also have studied and understood well control procedures and the concept of removal gas in ERD wells. The reason for this is that in conventional wells there is no accumulated and trapped gas at the end of the wellbore.
LITERATURE REVIEW
- Kick Detection
- Kick Identification
- Shut-In Procedure
- Killing Kick
The reasons are the effect of swabbing during exiting the hole, containment pressure, removal of the gas kick and mud tightness design. This is because the TVD at casing shoe is often close to the TVD of the inflow zone. The well inflow and outflow of the well must be balanced with continuous monitoring to prevent late kick detection.
For example, the drill string is removed from the wellbore when it trips out of the hole. In the event that after the kick is detected and a kick occurrence, the type of inflow type entering the wellbore must be determined. The problem with delaying closure of the valve to achieve complete shut-in of the well is the additional influx from the formation into the wellbore.
In the shut-in process, when the well is shut in, gas will migrate from the bottom to the top of the well. It is important to calculate the pump movements from surface to well and from well to surface to get the total time of the pump to close the well. First, the killer mud weight is briefly circulated at high speed to remove gas from the horizontal part of the well.
When the gas is expected to be circulated out of the horizontal section and into the hold, the kill rate can be reduced to a normal rate, usually 1/3 to 1/2 of normal drilling rate. In the holding section, the gas will remove and co-flow, and to circulate the gas out of the well, the normal kill rate should be sufficient. Then kill the well at a high kill rate for a short time just to remove the gas from the horizontal section of the wellbore.
To get a high kill rate, increase the flow rate of the mud by increasing the pump rate control. This reduction of kill rate is performed when the gas is expected to be circulated out of the horizontal section and into the bulk section. For the final section at the holding section, the gas will migrate to the surface and again normal kill rate is performed to circulate the gas out of the well.
METHODOLOGY
- Research Methodology
- Project Work Flow
- Equipment and Tools
- Project Activities
- Gantt Chart
Well control analysis has three modes, namely expected inflow volume, kick tolerance and kill sheet. After this, estimate the inflow volume and the detection time of the expected shock volume, which is also known. The next step is to analyze the impact tolerance and estimate the pressures as the impact circulates.
Then you create a destruction sheet and finally a report is generated from the information from the destruction sheet. It is used to calculate the bottom hole pressure (BHP) and the type of shock at the moment the inflow occurs. Stroke class, circulating BHP, static BHP, stroke interval pressure and underbalanced stroke interval are automatically calculated by the software. ii) Estimation of the volume of inflow.
The Results tab is used to display the results of total inflow volume, inflow volume at detection and time of detection. . iii) Temperature distribution. Type of inflow, kill rate, total inflow volume, kill mud gradient, and depth range to be controlled are specified in the Kick Tolerance mode. The drilling pressure in the well, assuming that all mud in the well was displaced by gas, can be calculated.
The scheme showed an animated simulation of the circulation process of the inflow to the surface. The string ring volume fraction, string volume fraction, and mud mass details are determined by the software. iii) Kill Graph. A void report is generated to review a summary of the information provided in the void dialog.
It also reports a summary of weak links, weighting requirements for kill mud and trip margin, pump stroke schedule and volume and capacities. For the second part, macro visual basic is used to compare the results with WELLPLAN.
RESULTS AND DISCUSSION
- Effect of varying total influx volume in kick tolerance and geometry of
- Kill rate
- Kill result
- Kill sheet
- Kill graph and Well control summary
Assuming that varying total inflow volume in kick tolerance will have the most effect on annulus pressure during kick occurrence. The experiment was performed with several simulation runs for different total inflow volumes with the ERD section and vertical section in the same well. From Figures 11 and 12, the increase in total inflow volume causes an increase in the annulus pressure.
For Section 1, an inflow volume of 15 bbl is the only acceptable inflow volume for Section 1, because the pressure in the annulus does not exceed the rupture pressure. However, the results show that the annulus pressure of an inflow volume of 30 bbl does not exceed the fracture pressure for Section 2. For this project, one of the objectives is to see the results of both WELLPLAN and theoretical calculations.
For Section 1 and Section 2 of the WELLPLAN, all experiment kill rates are enough to completely remove the gas kick from the wellbore. From the studies that have been done by reading books and journals, the kill rate should be high for section 2 to remove the gas kick. Next, for the theoretical calculations, using Equation X, the calculated kill rate for Section 1 is 15988.8 gpm and 755.8 gpm for Section 2.
One of the reasons why the result is too high is that the flow regimes in the drill pipe annulus and drill collar are assumed to be turbulent flow. Meanwhile, as shown in Table 8, the maximum Q is realistic and the result is suitable to remove the gas kick at the end of the well. Once the gas kick is removed at the end of the well, the kill rate is reduced by 1/3 to ½ of the drill circulation rate.
From the above results, to kill the well for Section 1, 212 blows were required to fill the KMW inside the drill string. The factor in this situation is that it only takes a few minutes to transport the KMW to the end of the well. If strokes per mine. are high, the time taken for the well control operations is less as shown in Figures 20 and 22.
Next, Figure 21 illustrates 2269 strokes are required in Section 2 to kill the well and it takes 56.7 minutes and 307.8 bbl from the surface to the target depth. The total time for the well control operation is 307.1 minutes and the number of strokes is 12285 from the surface to the target depth and from the target depth to the surface.
CONCLUSION AND RECOMMENDATION
Conclusion
Use high velocity for a short time to displace the gas shock from the horizontal part of the well. When the throttle pressure starts to rise to increase rapidly, the pumps must be slowed down. Observe the drill pipe pressure and keep it constant until the KMW circulates the entire well referenced to the total number.
WELLPLAN is really useful software in the analysis of the drilling operations and it is user friendly. This software can improve drilling performance by reducing kicks, stuck pipe, lost circulation and blowouts for significant reduction in non-productive time.
Recommendation
By having the right well control procedures in place, we can avoid the loss of valuable natural resources, increased drilling costs, environmental damage, increased regulations, personnel injuries, and the major consequence is loss of life. Arild, O., Ford, E.P., Loberg, T., and Baringbing, J.W.T., "KickRisk - A Well-Specific Approach to Quantifying Well Control Risks," paper SPE 124024 presented at the Oil and Gas Conference and Exhibition in SPE Asia Pacific , Jakarta, 4-6 August 2009. L.: “Gas-percussion experiments in oil-based drilling mud in a full-scale inclined exploratory well”, SPE paper 19561 presented at the 64th Annual Tech .
Schubert, J.J., Cheo, J., Gjorv, B., Long, M.: Development and Assessment of Well Control Procedures for Extended Reach and Multilateral Wells Using Computer Simulation, MMS/OTRC, TX (2004).
