Managed Pressure Drilling Techniques

CHAPTER 1
INTRODUCTION
Managed Pressure Drilling (MPD) is a new technology that uses tools similar to those of underbalanced drilling to better control pressure variations while drilling a well [4]. The aim of MPD is to balance the downhole pressure and manage the annular hydraulic pressure accordingly in order to improve the drillability of a well by mitigating the drilling problems, including stuck pipe, lost circulation and excessive mud cost.
MPD can improve economics for any well being drilled by reducing a rig’s nonproductive time (NPT). NPT is the time that a rig is not drilling [4]. Many of the drilling problems may be reduced by using MPD as such problems occurred. MPD introduces new techniques that require proper understanding of the drilling problems, becoming confident enough in the technology to use it on a regular basis takes time. With the resources that are currently uneconomical in the offshore markets and the problems that occur while drilling a well, it is important that industries look to MPD to improve the drilling ability of the drilling rigs.

1.1 Background
The MPD is an adaptive drilling process to precisely control the annular pressure profile throughout the well [1]. The main idea is to balance the bottom hole pressure and maintain within close tolerances and close to the boundary of the operation envelope defined by the pore pressure, hole stability envelope and fracture pressure. MPD uses many tools to mitigate the risks and costs associated with drilling wells by controlling the annular pressure profile. These techniques include controlling backpressure, fluid density, fluid rheology, annular fluid level, circulating friction and hole geometry in any combination.

1.2 Problem Statement
The economics of drilling offshore wells is important as we drill more wells in deeper water, horizontal and high pressure high temperature (HPHT) wells. Drilling-related problems, including stuck pipe, lost circulation and excessive mud cost show the need for better drilling technology. If we can solve these problems, the economics of drilling the wells will improve, thus enabling the industry to drill wells that were previously uneconomical.

1.3 Objectives
The objectives of this project are:
a. To establish that the MPD techniques can be used to balance the downhole pressure environment limits and manage annular hydraulic pressure profile accordingly.
b. To develop a design for MPD techniques successful application.

1.4 Scope of Study
To achieve the objectives of this project, the scope of study are:
a. To conduct in-depth research on the drilling offshore wells and its pressure variation.
b. To conduct in-depth research on the case study of the well control equipments during the drilling operation
c. To conduct the analysis and design on the MPD techniques to mitigate the drilling related problems.


CHAPTER 2
LITERATURE REVIEW
Generally, the drill string connection procedure mainly consists of five operation, the rotational drill string stopped, pumping of drill fluid stopped, new segment of drill string is mounted to the drilling string, pumping drilling fluid restarted and drill string is rotated and the normal drilling operation is restarted[5]. The starting and stopping of the drilling fluid caused severe fluctuation in the well fluids flow rate which influences the well pressure. With the use of the MPD techniques will reduce this doubt by adding the surface pressure that controlled from the surface so that the bottom pressure will be the summation of hydrostatic pressure, Frictional pressure and surface pressure.
Managed Pressure Drilling (MPD) allows us to manipulate the pressure in the borehole whilst drilling and this allows us to eliminate pressure related issues, increasing Rates of Penetration (ROP) and increase control of the well. During the manipulation of the pressure in the well, the following variables normally manipulated. The mud density, mud viscosity, flow rate, trapped pressure and friction pressure.

2.1 Underbalance Drilling (UBD) Vs. Managed Pressure Drilling (MPD)
MPD is similar to Underbalance Drilling (UBD), it uses many of the same tools and were designed for UBD operations. The difference between these two techniques is that the UBD is used to prevent damage to the reservoir during the drilling whereas the MPD is to solve the drilling problems. The UBD allows influx of formation fluids by drilling with the pressure of the fluid in the wellbore lower than pressure and the fracture pressure of the reservoir. It is set up to handle the influx of fluids that may occur while drilling but does not encourage influx. UBD is reservoir-issue related while MPD is drilling-issue related [4].


2.2 Pressure-Gradient Window
As the well is drilled, drilling fluid is circulated in the hole to obtain a specific bottom hole pressure. The density of the fluid is determined by the formation and pore pressure gradients and wellbore stability [2].
Figure 2.1 shows a pressure gradient profile of a well. This profile shows the change in pressure as the depth increases. The pressure window is the area between the pore pressure and the fracture pressure. The aim when drilling a well is to keep the pressure inside this pressure window. In a static well, the drilling, the only way to adjust the pressure during static conditions is to vary mud weight in the well.

Figure 2.1 Pressure-gradient profile [4]
Figure 2.2 shows the problem that can occur when dealing with tight pressure gradient windows. When the well is static, the pressure in the well is less than the pore pressure and the well takes a kick; that is, hydrocarbons flow into the well. Before drilling can begin again, the kick has to be circulated out. After a connection, the pumps restart, the BHP (Bottom Hole Pressure) increases, and the pressure goes above the fracture-pressure, resulting in lost circulation, or fluid flowing into the formation. The goal of MPD is to walk the line of the pressure gradients. Managing the pressure and remaining inside this pressure gradient window can avoid many drilling problems.


Figure 2.2 Pressure-gradient window for tight margins [4]

2.3 MPD Techniques
2.3.1 Constant Bottom Hole Pressure (CBHP)
The CBHP will equalize the bottom hole pressure during the drill pipe connection due the lost of friction pressure when the pump at the surface is stopped and the circulation fluid into the well is stopped [1].

2.3.2 Pressurized Mud Cap Drilling (PMCD)
The PMCD permits safe and efficient drilling in severe or total loss zones so that there will no return flow by pumping the viscous fluid or disposable fluid (water) through the drill pipe [1].
2.3.3. Dual Gradient (DG)
The DG is aimed to recover the expensive with zero discharge. In DG drilling the bottom hole pressure is maintained via combination of two fluid gradients [1].



CHAPTER 3
METHODOLOGY
3.1 The Methodology of Study
















Figure 3.1 Flowchart of the methodology research


CHAPTER 4
Result AND DISCUSSION
4.1 Result
This report will come up with the analysis and design of the MPD techniques i.e. Constant Bottom Hole Pressure (CBHP), Pressurized Mud Cap Drilling (PMCD) and Dual Gradient (DG).

4.2 Discussion
With the MPD technology it will reduce the NPT which minimize the rig cost. The drilling problems such as Kick and lost of circulation will be mitigated using MPD techniques.

CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1 Conclusion
MPD can solve many of the NPT problems that occur while drilling offshore. By solving these problems, MPD can improve the economics of the drilling wells and enable the drilling of wells that previously were taught to be uneconomical.

5.2 Recommendation
In applying MPD in the field, many variations are still being developed. Using compressible fluids with MPD is an interesting variation that would allow drilling with a balanced pressure using air, foam or mist. This could result in increasing ROP when drilling while still keeping the pressure inside the gradient window. Another variation is having the ability to strengthen the wellbore using solids in the mud to plug and support microfractures that form in weaker formations when using a higher density mud. This variation would not be adjusting the pressure gradient of the wellbore but would widen the window so that the well could be drilled successfully.

REFERENCES
[1] N. Steve, May 2009, Managed Pressure Drilling, Weatherford Solution Sdn.Bhd, Kuala Lumpur
[2] F.John,Dr., Drilling Engineering, Heriot Watt Institute of Petroleum Engineering, Edinburgh, Scotland
[3] H. M. Don, 2007, Controlled Pressure Drilling, Weatherford International Ltd, Texas, USA.
[4] M. D. Matthew. May 2006, Managed Pressure Drilling, Texas A & M University, USA
[5] N. Gerhard & N. Geir, Journal of process control 16 January 2006, Nonlinear model predictive control scheme for stabilizing annulus pressure during oil well drilling, Department of Electrical Engineering Technology and Cybernetics, Telemark University College, Kjǿlnes Ring 56, N-3901 Porgrunn, Norway
[6] L.C. William, Ph.D, Air and gas drilling manual, New Mexico Institute and Technology, Secoro, New Mexico

ilex seeking replacement rig for Timor Sea wells

Published: Jul 23, 2009

Offshore staff

PERTH – Oilex is aiming to conclude agreements concerning an offshore drilling project in block JPDA 06-103 in the Joint Petroleum Development Area (JPDA) of the Timor Sea.

The company is looking to farm out part of its 25% operated interest in the JPDA to reduce its financial exposure. It describes this as an attractive oil exploration opportunity, with the potential to host significant reserves near to existing fields already in production, and also to Eni’s Kitan oil discovery.

During the second quarter of the year, mapping of prospects in the JPDA was completed. The joint venture partners singled out the Lore and Lolotoe structures – both in water depths of below 400 m (1,312 ft) – as the first two candidates for drilling. Lore has prospective resources in the range 20-515 MMbbl, and Lolote 14-22 MMbbl.

Transocean has terminated a contract entered into by the partners last year for the semisubmersible Transocean Legend following Nexus’ decision to cancel a prior contract for the rig.

The partners are pursuing other options – Oilex points out that the Transocean Legend’s deepwater capability would not have been necessary in any case for the wells on Lore and Lolotoe, and more rigs are currently available than was the case when the contract was signed in 2008.

The joint venture has also applied to ANP for an extension to the production-sharing contract to allow the wells to be drilled under a revised schedule.

07/23/2009

Japan energy farms into Timor Sea block

MELBOURNE, Aug. 4 -- Japan Energy Corp. has farmed into Joint Petroleum Development Area Permit 06-103 between Timor Leste and Australia in the Timor Sea.

The company has taken a 15% interest from Oilex Ltd., Perth, which has retained a 10% interest in the block.

Oilex will be refunded part of its previous costs as well as future funding for its remaining 10% share of costs of two commitment wells up to an agreed cap. Oilex will remain operator of the permit.

The permit is seen as prospective because of ENI’s discovery of Kitan oil field nearby and the Kuda Tasi and Jahal discoveries farther north by BHP Petroleum in the 1990s.

Oilex also points to Woodside’s Laminaria/Corallina oil fields to the west and ConocoPhillips’s Bayu-Undan gas-condensate field to the south.

Oilex hopes to secure a rig to drill the first two prospects on permit 06-103 during the second half of this year.

The deal with Japan Energy is conditional on an extension to the third year of the production sharing contract as well as government approvals.

Other companies in the block are Global Energy with 25%, GSPC with 25%, and Bharat Petroleum Resources with 25%.
Source:
Oil & Gas Journal

INFLUENZA-LIKE DICEASE

Good news from PM and PR of Timor Leste

Prime Minister Xanana Gusmao and President Dr.Ramos Horta in the recent joint news conference in Dili, Timor Leste. They are pretty sure the gas pipeline from Greater Sunrise should go to Timor Leste.

We are happy about it, they have been aggressively engaging a lot of negotiation and we wish the negotiation will bring us something that can benefit for our sovereign country. As they said in the technical point of view it is feasible the pipeline go to Timor Leste. Which seems the main drive for this negotiation, but we should aware that with the current technologies and more to come, make possible the pipeline can go through our ocean and eventually end up in one of our coastal area in Timor Leste.

But, the question is, Do the companies in charge agree with it? because it is not just about the technical issue but there are many issues that need to be settle before it can realize.

As an engineer there is no doubt about technical wise for the pipeline to go to Timor Leste's territory, the issue is about the companies that want to invest, is it safe to go there?, Is enough local manpower to handle majority of the work? and the most crucial is that about the marketing opportunities.

To answer all of these doubts and unanswered questions there are many things that need to be seen by the government both present and in future.

Eni awards Kitan subsea equipment contractto FMC

HOUSTON – Eni has awarded a $60-million contract for manufacture and supply of subsea equipment for Kitan field development in 1,000 ft (310 m) of water in the Timor Sea.

Under the agreement, FMC will supply three subsea production trees and all associated control systems and umbilicals. Engineering, procurement, and construction will be from FMC operations in Singapore and Malaysia. Delivery is scheduled to begin in 2010.

06/17/2009

Managed Pressure Drilling (MPD)

As I wrote in previous post, that the MPD is a new technology in the Drilling operation, many of us wonder we will run out of oil/gas in near future and with that the world will face energy crisis, but Don't you think that we have more reserves in far-far below the earth beneath, therefore as we go for it, it certainly requires great technology to deal with.

The MPD is one of the latest technology that not only reducing the cost but also the safety of the environment as well as the personnel on board during the drilling operation. As we go into the more hazard zone it is essential the safety cautious will be taken seriously for both our crews and for the environment specially in the offshore operation.

Many might wonder, what is the MPD, the MPD is actually similar with Underbalance drilling (UBD) both of them use similar tools such rotating control device (RCD) and manifold choke (valve) the only different is that the UBD aims to control the formation damage however, the MPD is to improve drillability of a well by alleviating drilling issues such as kick,lost of circulation etc that may arise during the drilling by preventing the formation damage.

It is important the energy companies should taken into serious consideration to use MPD in their drilling operation, as it has valuable advantages from the economics point of view until the safety concern.

The drilling offshore operation like in Timor Sea is one of the candidate that might use MPD in the both exploration and development stages, Petronas (Malaysian national oil company) will drill three wells in the area of JPDA in middle of August 2009, hopefully in this exploration drilling may use the MPD in their operation.

It is understood that the MPD is new technology specially in the Asia Pacific, therefore, the MPD is not that familiar yet, but in North Americas and Gulf Mexico the drilling companies use the MPD at few deep and ULTRA DEEP water and the result were fantastic, and also most well are deviated with the angle above 70 degree. therefore in my new design of MPD which will be partial of my dissertation draft in Bachelor of Mechanical Engineering, major in Petroleum Engineering that will more focus in the economics point of view as it is important to find alternative cheapest way in the drilling operation, but not also to forget the safety issue both for the personnel and environment.

It is important to us as the the citizens of Timor Leste, should aware of the all new possible technologies specially in area of Petroleum Engineering, which oil and gas accounted of 80% of the country's revenue.

Therefore, let us put more resources in the area of R&D for the future drilling in our both offshore and onshore oil/gas reserves, and i have good faith we will be able to handle it and more importantly soon or later we will stand independently in term of R&D, it is just a matter of time, but as the end we will reach there.

It is a positive sign of existing new establishment of the National Petroleum Authority or Nasional Autoridade de Petroleuo (ANP) will help to start with the center of R&D in Dili or some other suitable locations in the country to gather young and enthusiastic future petroleum engineer to contribute their goal and knowledge in order to come up with common goal.