## Top Kill Failed

After I stepped out of the plane from New York City to Beijing, I got to know that top kill failed and BP was about to start another plan. The new plan is to cut off the broken riser pipe, put a cap over it and use a new pipe to siphon oil to containment ships on the surface[1].  Till the moment I am writing this post, two attempts have been failed. BP began the third one[2]. This method has potential risks that the flow of oil could temporarily increase by 20% before the new device is put in place. Will this method work? I wish, but no confidence at all.

The failure of BP’s tries to stop the leakage is challenging the local community’s endurement[3, 4]. Even, BP gas stations were to reponsible for the incident[5]. In addition, lawmakers are considering tough new measures aimed at ensuring that the oil industry pays the economic and environmental costs of spills. The $75 million fine cap of oil spill may be changed to$10 billion or unlimited, which would make BP bankrupt[6]. Now only rational decision could save the planet and the people. I cannot agree with either the boycott to BP gas stations or unlimited fine on BP’s fault. It is much easier to ruin anything than create it. The environment is the one, so BP is.

## Aftermaths of Deepwater Horizon Explosion

1. Oil Leakage

Live video from the ROV monitoring the damaged riser

BP sees ‘some success’ with top kill method

2. Oil Spill

Oil spill tracker

3. Offshore Drilling Banned

New offshore drilling limited

According to the latest news, BP’s partial success on top kill is the only good one to the industry. After having visited gulf of Mexico, on Thursday President Obama banned new drilling in deep coastal waters and ordered floating rigs to stop work on some 30 exploratory wells, while the producing well exempt. The oil spill tracker and the live video from the ROV could be used for reference.

## Deepwater Horizon (Updated)

This afternoon when I was waiting for the flight from St. Louis to New York City, CNN live reported BP was working on the  Top Kill job, which started from 1PM local time today. Live videos showed the crude plume was rolling up underwater. The oil spill onshore is worse and worse. The anchor Anderson Cooper sampled a bottle of water-oil emulsion, which is similar to the oil sample I have ever seen in our lab. At that time, I was thinking perhaps Dr. Yongfu Wu, a research professor in our group, have some ideas on how to treat the emulsion. Several months ago, he proposed a method to separate oil from the emulsion with lower cost. Of course, for the oil spill in gulf of Mexico, the most important thing is to recover the oil from the contaminated area, and reduce the damage to the environment, instead of the original target of enhanced oil recovery during hydrocarbon production. In addition, I read some useful materials about the ongoing story as shown in the two links below.

1. Oil Spill

Some oil spill events from Wednesday, May 26, 2010

It is the first time for me to read the summary by Associated Press. I think it is a good summary about the oil spill for today (maybe every day).

2. Control Mechanisms

BP Briefs US Government on Initial Perspectives of Deepwater Horizon Investigation – Focus is on Seven Control Mechanisms

The following seven processes, systems or equipments should have prevented the accident (1 through 5) or reduced the impact of the oil spill (6 and 7).

1. The cement that seals the reservoir from the well;

2. The casing system, which seals the well bore;

3. The pressure tests to confirm the well is sealed;

4. The execution of procedures to detect and control hydrocarbons in the well, including the use of the BOP;

5. The BOP Emergency Disconnect System, which can be activated by pushing a button at multiple locations on the rig;

6. The automatic closure of the BOP after its connection is lost with the rig;

7. Features in the BOP to allow Remotely Operated Vehicles (ROV) to close the BOP and thereby seal the well at the seabed after a blow out.

The first three made me think of the cumbersome calculation of well design. I am not familiar with the industrial design. I guess they should have some special program to do the calculation in fields. One step of the calculation needs try and error method. Usually three trials should be okay. But in fields, decision making is extremely important, which related to people’s lives and wealthy. The incident has caused billions of dollars of loss for BP and US. The effects of ecological disaster will last more than decades. Now the easing offshore drilling policy seems to be tough again. And the oil industry got another hit, much heavier than President Obama’s bias on fossil energy industry. Petroleum engineers have to worry about the future of the industry.

## Deepwater Horizon Explosion

Note: This post summarizes the incident occurred one month ago. The context is partially modified from Deepwater Horizon and some other relative terms on wikipedia.org.

On April 20, 2010, an explosion occurred on Deepwater Horizon, an offshore rig owned by Transocean and leased by BP, and it caught fire.[1] Two days later, it sank in water approximately 5,000 feet (1,500 m) deep, and has been located resting on the seafloor approximately 1,300 feet (400 m) northwest of the well .[2]

INTRODUCTION

Deepwater Horizon is a Reading & Bates Falcon RBS8D design, Hyundai Heavy Industries build, 5th generation deepwater semi-submersible drilling unit capable of operating in harsh environments and water depths up to 8,000 ft (upgradeable to 10,000 ft) using 18¾in 15,000 psi BOP and 21in OD marine riser.[3] Construction started in December 1998 and it was delivered in February 2001 after the acquisition of R&B Falcon by Transocean. Since arriving in the Gulf of Mexico, Deepwater Horizon was under contract to BP Exploration. Its work included wells in the Atlantis and Thunder Horse fields, a 2006 discovery in the Kaskida field [4] and the 2009 Tiber oilfield.[5] In 2002, the rig was upgraded with “e-drill”, a drill monitoring system where technicians based in Houston, Texas receive real-time drilling data from the rig and transmit maintenance and troubleshooting information.[6] On September 2, 2009, the giant offshore rig drilled on the Tiber oilfield the deepest oil and gas well ever drilled with a true vertical depth (TVD) of 35,050 feet (10,680 m) and measured depth (MD) of 35,055 feet (10,685 m), of which 4,132 feet (1,259 m) was water.[7] In October 2009 BP extended the contract for Deepwater Horizon by three years, to begin in September 2010.[8] The lease contract was worth $544 million, a rate of$496,800 per day.[9]

Fig. 1 Deepwater Horizon Offshore Rig

BACKGROUND

Before the accident, it worked on BP’s Mississippi Canyon Block 252, referred to as the Macondo prospect.[10] The rig caught an explosion when it was last located approximately 41 miles offshore Louisiana on Mississippi Canyon block 252. [11]

Fig. 2 Location of Deepwater Horizon [12]

EXPLOSION

Though the cause of the explosion on the Deepwater Horizon remains under investigation, officials with Transocean have said a blowout within the deep oil well was likely to blame for the deadly blast. At the time of the accident, half of the crews were cementing, and the other half were installing casing to secure the walls of the well. [13] It was the rig in the final phases of drilling a well in which casing is cemented in place, reinforcing the well. This is a delicate process as there is the possibility of a blowout, the uncontrolled release of formation fluids from the well. [14]

The fire reportedly started at approximately 10 PM CST on Apr. 21, 2010. [11] Adrian Rose, a vice president for Transocean Ltd., said that there was “no indication of any problems” as crew members carried out routine work around the drill site before the blast. Officials said 126 people were on board at the time of the explosion. Of the 115 accounted-for workers, 17 injured were evacuated by helicopter from the rig, and another 94 people were taken to shore with no major injuries, and four more were transferred to another vessel, according to the Coast Guard. The rest of 11 were missing. [15]

Fig. 3 Deepwater Horizon was on fire[16]

Fig. 4 Deepwater Horizon was on fire[16]

According to survivors words, the sudden explosion gave them less than five minutes to escape as the alarm went off, and Chad Murray, 34, the rig’s chief electrician said he didn’t think any of the missing could have survived. [17]

The United States Coast Guard (USCG) launched a massive rescue operation.[11] One day after the explosion USCG spokesman Mike O’Berry said four helicopters, four Coast Guard boats and a plane were helping search for the missing workers. [18] Two USCG cutters continued the search overnight. By 6 AM of Apr 22, USCG has surveyed 1,940 square miles in a series of 17 separate air and sea search missions since the Tuesday explosion. [19] Official confirmed Murray’s word on Thursday and USCG stopped the search for the 11 missing persons. [20]

Fig. 5 United States Coast Guard Rescued the Wounded[19]

After the blast, the rig was tilting as much as 10 degrees. [21] Fire boats sprayed the rig with water in an unsuccessful bid to douse the flames. After burning for more than a day, Deepwater Horizon sank in water approximately 5,000 feet (1,500 m) deep, and has been located resting on the seafloor approximately 1,300 feet (400 m) northwest of the well on April 22, 2010. [2]

Fig. 6 Anchor Handling Tugs try to extinguish the oil rig explosion blaze on the Deepwater Horizon[16]

Fig. 7 Anchor Handling Tugs try to extinguish the oil rig explosion blaze on the Deepwater Horizon [19]

INVESTIGATION

On the day Deepwater Horizon sank on the bottom of Gulf of Mexico, the USCG and the Minerals Management Service launched an investigation on possible causes of the explosion. [22] According to interviews with rig workers conducted during BP’s internal investigation, a bubble of methane gas escaped from the well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding.[23] The blowout preventer (BOP, a huge and complex tower of valves and pipe crimpers on the ocean floor designed to shut down a well in an emergency) was supposed to activate once the escaping gas was detected and the alarm went off, but unfortunately it didn’t work. Bob Fryar, senior vice president of BP’s exploration and production operations in Angola, in southwestern Africa said BP had found there were some leaks on the hydraulic controls on the BOP, though it is unclear whether it caused the malfunction. [24]

AFTERMATH

Shortly after the explosion, the concern about the crude oil spill from the incident on the environment became more and more serious because the failure of BOP caused the oil leakage from the borehole.[25] Since BP has taken several measures (1. A remotely operated underwater vehicle attempting to turn on the Deepwater Horizon blowout preventer;[26] 2. BP now aims to deploy a small “top hat” dome over the leak after its effort over the weekend to cover it with a huge metal box was stymied by a buildup of crystallized gas hydrates;[27] 3. After several attempts, BP successfully inserted a 6 inches wide tube into a jagged 21 inches pipe that is leaking oil onto the Gulf seabed, which is surrounded by a rubber seal and attached to a tanker at the surface.[28]) to stop the oil leakage from the borehole, the spill is expected to eclipse the 1989 Exxon Valdez oil spill as the worst US oil disaster in history.[29] BP is leading the clean-up work of oil spill, and working with US government, communities, and organizations. [30]

Fig. 8 A remotely operated underwater vehicle (ROV) attempting to turn on the Deepwater Horizon blowout preventer[26]

Fig. 9 The oil slick as seen from space by NASA’s Aqua satellite on April 25, 2010 using its Moderate Resolution Imaging Spectroradiometer (MODIS) instrument[31]

## LaTeX Tricks (2)

I have been working on my dissertation using LaTeX for one week. Most of the contents came from my proposal. Now the structure has been set up and it is around 40 pages already. The next step is to fill the blanks. During the time period, I solved some problems by some tricks found on the Internet.

1. Upper or Lower case:
It is very easy to write upper or lower case in LaTeX. The cubic meter could be written as $m^3$ by $m^3$, but the display is mathematical, and the letters shows italics. If add \text in front of the code as $\text m^3$, the normal font appeared[1].

2. Multi-row Table:
Sometimes we need special tables. Multirow (multicolumn) command provide more choices.
Here is one simple example:
\begin{table}[h]
\centering \caption[Particle Size Distribution of
$\text{LiquiBlock}^{\texttrademark}$ 40K]{Particle Size Distribution
of $\text{LiquiBlock}^{\texttrademark}$ 40K}
\begin{tabular}{|r|r|r|r|}
\hline
\multirow{2}*{Mesh} & Size & Weight& Percentage \\
& (mm) & (g)& (\%) \\
\hline
18 & 1.000 & 9.14 & 2.29 \\
20 & 0.850 & 134.95 & 33.85 \\
30 & 0.600 & 134.21 & 33.66 \\
40 & 0.425 & 63.25 & 15.86 \\
45 & 0.355 & 20.85 & 5.23 \\
50 & 0.300 & 16.91 & 4.24 \\
60 & 0.250 & 14.90 & 3.74 \\
70 & 0.212 & 0.14 & 0.04 \\
$<$70 & $<$0.212 & 4.34 & 1.09 \\
\hline
\end{tabular}
\end{table}
It seems that wordpress does not support Table function of LaTeX. Please see the snapshot of the table below.

3. No Indent
Sometimes the journal requires no indent at the beginning of each paragraph[2].
\setlength{\parindent}{0pt}

Reference:

## LaTeX Tricks (1)

Last night a simple version of my dissertation has been created by LaTeX. As a fresh hand in LaTeX, there are so many things to learn, especially the tricks. A short summary for my work last night could be found below:

• Convert the .jpg file to .eps file:

LaTeX supports .eps files very well. It is possible to insert jpg pictures into LaTeX, also. From my experience last night, .jpg files maybe troublesome for LaTeX. Image-Pro Plus has ever been used to convert .jpg files into .eps files. Also, HP LaserJet 6P/6MP PostScript printer could do this job. Finally, I found another easy way. Now most TeX software embedded such kind of tools as bmeps.exe.[1] Type the following command under DOS mode in the folder where .jpg files are saved:

X:\bmeps *.jpg *.eps -c(if no -c, black and white pictures were generated).

• Insert .eps files in LaTeX

As previous description, LaTeX supported .eps files for a long time, and they linked with each other very well. All the textbooks about LaTeX just gave a brief instruction on how to insert .eps files in LaTeX. But, when I was trying to do the same thing following the instruction, the results disappointed me. After having done research on the Internet, I found latexpdf command could not read .eps files.[2] The solution is to compile the TEX files using latex command, then convert. dvi files into pdf using dvipdf command.

And another webpage I found last night provides more LaTeX tricks, which is kept here for future use.[3]

References:

## Determination of Perforation and Production Strategy for Single Well with Aquifer using CMG

Note: This is the third project for the reservoir simulation course. A radial model has been used to simulate a single well with bottom aquifer. The perforation and production strategy were determined through the reservoir simulation.

Description of the Reservoir

A target petroleum production unit is given in this project. To construct a radial model, assume the outer radius is 200 m, and the thicknesses of three layers are 8 m, 8 m, and 4 m, respectively. The water-oil contact is  -3140 m; and the bubble point pressure is 10000 kPa. There is an aquifer that is 50 m thick connecting to the bottom of the production unit. The aquifer has the same permeability, 200 md, and porosity, 0.20, with all layers. Rock properties, relative permeability, and PVT data are the same as previous project, Comparing the Performance of 5-Spot and Inverted 9-Spot Patterns by Reservoir Simulation using CMG Suite. The aquifer is 2.5 larger than the reservoir. Figure 1 shows the simple model for production unit and aquifer.

Figure 1. A simple model for production unit and aquifer.

Parameters to determine the size of radial grids include:

• Number of divisions alone radius direction: 15
• Number of divisions alone theta direction: 5
• Grid block width in radius direction: 3, 5, 8, 10, 10*15, 24

There is a production well in the center of the production unit, meaning the well location in the grid system is (1,1). The production started from January 1, 1995; the liquid production rate is 50 m3/day; all layers are perforated for production. Production well constraints are: min bottom hole pressure 1500 kPa and max liquid production rate as 100 m3/day for operation, and max water cut is .95 for monitor and shut-in conditions.

• Water Cut

Put the simulation stop time card at Jan. 1, 2020, determine the date/time that water breaks, and water cut reaches 50, 60, 70, 80, 90 and 95%.

Dates of Water breaks, and water cut reaches 50, 60, 70, 80, 90 and 95% could be determined through Figure 2. Water Cut vs. Time Curve, and listed in Table 1.

Table 1. Water Cut vs. Time

 Water Cut Water Break 50 60 70 80 90 95 Date 01/01/95 05/01/00 09/01/00 04/01/01 01/01/02 12/01/03 11/01/05

Fig. 2 Water Cut vs. Time Curve for Base Case

• Perforation Strategy

There are 7 perforation plans for base case, which are layer 1+2+3, layer 1+2, layer 1+3, layer 2+3, layer 1, layer 2, and layer 3, respectively. Figures 3-6 show the water cut curves, cumulative oil production, oil production rate, and average reservoir pressure with various perforation plans. The water cut curves could be separated in to three groups based on the time water cut reaches the peak and the shape of the curve:

• Group 1, all the perforation plans including layer 1, such as layer 1+2+3, layer 1+2, layer 1+3, and layer 1;
• Group 2, all the perforation plans including layer 2 but excluding layer 1, such as layer 2+3, and layer 2;
• Group 3, layer 3 only.

Layer 1 dominates the water production in group 1, and layer 2 dominates the water production in group 2.

At early time, layer 1 only produced least water, while layer 3 only produced most. And Group 1 has shortest production history, and group 3 has longest production history. If only taking water cut account, perforating layer 3 only should be best. But, there are still something others we need to consider, such as recovery, oil production rate, and average reservoir pressure, etc.

From Fig. 4, the cumulative oil production curve, layer 1 only could produce the most oil (130.54 MS m3), while layer 3 only could produce the least (128. 36 MS m3). The, the choice should be layer 1 only. Figures 4 and 5 confirm this suggestion. Layer 1 has the longest stable oil production rate with 50 m3 per day.

Fig. 3 Water Cut with Various Perforation Plans

Fig. 4 Cumulative Oil Production vs. Time with Various Perforation Plans

Fig. 5 Oil Production Rate vs. Time with Various Perforation Plans

Fig. 6 Average Reservoir Pressure with Various Perforation Plans

• Critical Production Rate

To find an optimum or critical production rate, 4 more production rates have been tried, such as 30, 40, 50, 60, 70 m3 per day. Figures 6-9 show the water cut curves, cumulative oil production, oil production rate, and average reservoir pressure with various production rates.

Figures 7, 9, and 10 show that the less production rate, the longer oil produced, and the slower average pressure dropped. Those three figures could not tell which production rate is the best one, while Fig. 8, the cumulative oil production could. The pink curve which represents the oil production rate at 60 m3 per day is higher than any other, which is 130.98 MS m3.

Fig. 7 Water Cut with Various Production Rates

Fig. 8 Average Reservoir Pressure with Various Production Rates

Fig. 9 Oil Production Rate vs. Time

Fig. 10 Average Reservoir Pressure with Various Production Rates

• Effects of Permeability Anisotropic Ratios

To find out the effect of permeability anisotropic ratios (kv/kh) on the performance of the well, 3 more ratios have been tried, such as 0.01, 0.5, and 1.0. Figures 10-13 show the water cut curves, cumulative oil production, oil production rate, and average reservoir pressure with various permeability anisotropic ratios.

All the figures show that the performance of permeability anisotropic ratio being 0.01 is significantly from those other three. At early time of production, the higher permeability anisotropic ratio, the earlier water breaks and the higher water cut is (Fig. 11). Since for the case that permeability anisotropic ratio is 0.01, the water break very late and water cut is lower than others at early time, water cut increases very fast, and reached the limitation fastest. At late time of production, there is no difference between 0.1, 0.5, and 1.0. From Figs. 13 and 14, the case that permeability anisotropic ratio is 0.01 has the longest stable production time, and lowest average reservoir pressure, because no cross flow exists. The permeability anisotropic ratio of 0.01 means fluid can only flow in horizontal direction, and pressure can effectively drive the fluid flow through the reservoir rock. That could be confirmed by the cumulative oil production data showed on Fig. 12 and Table 3.

Fig. 11 Water Cut with Various Permeability Anisotropic Ratios

Fig. 12 Cumulative Oil Production with Various Permeability Anisotropic Ratios

Fig. 13 Oil Production Rate with Various Permeability Anisotropic Ratios

Fig. 14 Average Reservoir Pressure with Various Permeability Anisotropic Ratios

Table 3. Cumulative Oil Production and Recovery with Various Permeability Anisotropic Ratios

 Parameters Permeability Anisotropic Ratio 0.01 0.1 0.5 1.0 Cumulative Oil Production (MS m3) 133.92 130.98 129.08 128.99 Recovery (%) 44.377 43.400 41.430 42.743

Summary

1. Perforating Layer 1 only and the liquid production rate is set up at 60 m3 per day is the optimum production plan.
2. Lower permeability anisotropic ratio has better performance due to less cross flow.