Drilling Blowout.docx

FAKULTI KEJUTERAAN KIMIA

Assignment 1 Topic: A Case Study on Blowout and Its Control in KrishnaGodavari

Members KHAIRUL HADI BIN HASHIM MOHAMMAD FIKRI BIN HUSAILI MOHD FIKRI BIN NASIR

Student ID 2017466142 2017466178 2017466156

MOHD RAFIQ BIN MOHD ZUBIR MUHAMMAD AIMAN FAISAL BIN MOHD ZAILANI

2017466188 2017466168

Madam Husna Hayati Binti Jarni ……………………………………………………………… Date: 29.3.2019

A Case Study on Blowout and Its Control in Krishna-Godavari 1.1 Causes Controlling the subsurface pressure is very importances in the drilling operations. Improper well control procedures will lead to uncontrolled flow of hydrocarbons to the surface which is known as blowout that had happened in Krishna-Godavari (KG) Basin, East Coast of India. The sedimentation rate in the deltas of KG basin is high, so the water initially present in the pore space cannot escape out and result in overpressured formations. The formation pressure at the basin is two times larger than the normal hydrostatic pressure. So, improper procedures can easily cause blowout at these formations as the hydrostatic pressure cannot withstand the formation pressure. The basin also contains a lot of gas resources. Drilling too fast in the gas reservoirs may cause blowout because the gas contained in the formation being drilled can mix with the drilling mud resulted from underbalance pressure. This cause the drilling mud to become gas cut and lightened to the surface. 1.2 Action taken to control blow out. There are many actions that can be taken to control kick or blow out. Firstly, all signs such as loss circulation and increase in mud pump need to be well monitored and the information should be passed on to the crew working at the well site. Second, the reservoir and well parameters such as pore pressure, bottom-hole pressure to be maintained and initial pumping pressure and mud density should be calculated while killing the well. Third, advisable to have a detailed study about the history of blowouts occurred previously in this region and the geological setting of the basin in terms of presence of over pressures and different pressure regimes in different parts of the reservoir. Lastly, wells must be designed carefully with casing seats selected scientifically. The rough depth estimate of high pressure zones should be known from exploration geologists before drilling a well. The presence of high pressure formations should be known before hand through ROP to avoid the possibility of formation breakdown. 1.3 Equipment Based on the case study at KG basin, the blowout of gas were happened during drilling process where the calculation and inspection of kick were error because they were calculated that no kick happened when the drilling bit stuck in the borehole to pull it. Hence, they just leave the bit and pipe in the hole without proper inspection and using blowout preventer (BOP) for more safety action. The other equipment that they should use is the equipment where can adapted to the well performance at that area and should be tested the equipment regularly to avoid any low performance. Conclusion Well control is very vital not only it prevents accidents, it also prevents material and financial losses and damage to the environment. In this case, drilling through shallow gas sands was determined to be the reason of failure. In shallow well, gas is capable of rapidly moving to the surface. The best options to prevent the blowout is the combination of blowout consciousness management, reliable equipment and well-trained drilling crews to detect the signs of kick or blowout. Magnificently, the company was able to bring the situation under control after 3 days of focusing on the relief work and that has permitted future drilling of wells in the area by the public. However, an in-depth knowledge of geological setting of the East Godavari sub-basin is required before drilling wells in this area as safety measure to prevent the occurrence of another blowout.