Well, Idk but seems like they werent well prepared for the real deep water world and are still trying to justify spending money on a project that was way over thier heads.
This is the closest thing to a technical report we have ever had! Too bad it didnt come from the company some of us have invested in for 12 years + "Remarkable Progress"?.
There was no mention of biogenic gas as farrell indicated unless shallow gas is biogenic or shallow hydrate. Bottom line there is something there. Will we ever get the goods or the truth? More drilling here? They were obviously instructed to play in safe and gather data and were scared to death with the "harsh marine operating environment, the underground situation is more complex compared with onshore drilling" Wow really, did they think it was Oklahoma?! 90 cents to 7 cents just because we had timid inexperienced operators imo.
Key West African deepwater drilling and completion techniques
2013-08-12 13:52 Published :2013 -08-12 13:52 Source: Petroleum Drilling Techniques Hits:
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BP?Shell?Petrobras?StateoilTransocean... Abstract: At present, the world attaches great importance to deepwater oil and gas exploration and development, to BP, Shell, Petrobras, Stateoil as represented by Transocean and other oil companies and service companies represented mastered the key technology of deepwater drilling and completion, dominates the deepwater oil and gas exploration and development ... ?,?BP?Shell?Petrobras?StateoilTransocean? Currently, the world attaches great importance to deepwater oil and gas exploration and development, to BP, Shell, Petrobras, Stateoil as represented by Transocean and other oil companies and service companies represented mastered the key technology of deepwater drilling and completion, dominates the deepwater oil and gas exploration development operations.
? In recent years, China's three major oil companies have conducted a deepwater drilling and completion technology research, also conducted a deepwater drilling attempts, but with foreign companies, there is a big gap, still in its infancy. ?2007 Since 2007, Sinopec around the country "going out" strategy, and actively participate in overseas offshore oil and gas exploration and development risks. 000 m3 500 m, Currently abroad reached 26 deepwater blocks, water depth were over 1 000 m, maximum depth 3 500 m, distributed in Angola, Brazil, Nigeria and Indonesia 4 countries. ? Among them, the identity of the operator in West Africa Nigeria - Sao Tome and Principe Joint Development Zone (JDZ Blocks) and other deepwater oil and gas exploration work carried out, through equity participation in Angola, Brazil, Indonesia and other deep waters to carry out a number of oil and gas exploration and development blocks jobs.
?? A West African JDZ Block Overview
JDZ,?150~200 km,30 000 m2,1 400~2 000 m,????1 600 m? JDZ block is located in the deepwater Gulf of Guinea, from the Nigerian coastline of about 150 ~ 200 km, covering more than 30 000 m2, depth of 1 400 ~ 2 000 m, an average depth of 1 600 m. ? Geological background in the Niger Delta basin, oil and gas resource-rich but more complex depositional and structural characteristics.
Akata?Agbada?Benin Niger Delta Basin Cenozoic strata from top to bottom can be divided into Akata, Agbada and Benin 3 groups. Benin,Agbada Benin Formation with massive non-marine sandstone, Agbada Formation in shallow marine and fluvial sand, silt and clay-based. Akata? Akata Formation is a marine deposits, mainly in the thick clay layer and turbidite sand (Sham potential reservoir rocks), siltstone (large set of shale lenticular sandstone) composition of the Niger Delta Basin, the main source rocks, which large set of lenticular sandstone shale good as closed, often containing high pressure gas and water.
? As harsh marine operating environment, the underground situation is more complex compared with onshore drilling, deepwater drilling technology and equipment requirements are higher there, below the mud line shallow fluid (shallow stream, shallow gas, shallow hydrate) hazards Large, narrow windows security density, low temperature drilling fluid and cement slurry rheological properties of large, well control requires higher technical problems, which led to risky deepwater drilling and the cost is extremely high, drilling day rate of 40 to 100 million U.S. dollars, or even higher. JDZ?? JDZ Block of exploration blocks, almost no reference has been drilling data, so the block operating environment, seabed topography, shallow potential geological hazards, formation pressure systems, the lack of information, while the lack of mature and practical conditions of the narrow density window the drilling, well control and other technology and deepwater drilling fluid under low temperature conditions, slurry and construction technology. This is a direct result of drilling design, equipment selection, well structure optimization, slurry and drilling fluid system optimization, process optimization and cost control drilling uncertainty drilling risky.
——Bomu-l? Sinopec deepwater drilling and completion programs in West Africa and key technologies based on the research, as operator, has successfully completed the first well in the block - Bomu-l well drilling design and construction of the well water depth 1 655 m, is BP as operator, completed our first port of deep wells, drilling in the history of our country has very important significance. ??Bomu-l?Oki-east-l? On Bomu-l wells conscientiously sum up and continue to improve deepwater drilling and completion on the basis of supporting technologies, Sinopec as operator of the block has completed four other saliva deeper than 1 600 m of deepwater oil and gas well design and construction, which Oki-east-l wells operate in water depths up to 2 092 m, and basically formed and mastered the key technology of the West African deepwater drilling and completion operations management system.
?? Second, key technology research deepwater drilling and completion
1? A shallow hazard identification and control technology
? Shallow hazards (including shallow gas and shallow water, etc.) identification and control is to ensure that the safety of deepwater drilling one of key technologies.
Shallow hazard identification most direct and effective way is to pre-drilling before drilling design drill collar wells located, but the method is time consuming and will greatly increase drilling costs. ? To this end, researchers have proposed geophysical techniques to identify high-precision evaluation of the application of shallow hazards approach. ? The core of the method is the use of multi-channel digital technologies such as seismic surveys and topographic surveys and shallow, medium and deep stratigraphic surveys combined utilization highlights identification method, physiognomy method, acoustic velocity spectrum identification method from seismic data identify shallow gas, using seismic reflection and inversion identification identification method to identify shallow water.
Shallow gas and shallow water flow control methods are mainly two kinds, one drilling Control Act, two wells is to shift method.? The former applies to shallow gas (shallow water) and not the amount of strata relatively stable, the core is the use of a suitable drilling fluid density, to ensure that neither the narrow density window formation pressure without drain overflow occurs while the borehole cause wellbore instability or loss of control, so a reasonable wellhead well control and submarine detection devices is essential. ? The latter is mainly applied to soft formations, diagenetic poor and shallow gas (shallow water) than the larger situation. West African deepwater geology and drilling practice shows that the method is to control the shallow gas (shallow water) the most effective way.
2? well structure optimization techniques
Jdz 1600 m,? JDZ Block operations deeper than 1600 m, formation pressure prediction has some uncertainty fracture pressure low density and safe narrow window. Considering these factors and the operating characteristics of a security priorities and reduce operating costs for the principles presented well structure optimization ideas: surface casing pipe and drill hole section with seawater, to take injection mode servant catheter surface casing using eyes open hole section robin fashion drilling and so on. Well structure optimization design method based mainly include catheters and catheter carrying capacity subsea wellhead down into the depth of the injection method for determining (see Figure 1), based on opening the eyes of the surface casing servant circulation drilling depth and hydraulic parameters determination method, the pressure is not determine the level and under conditions of deep casing and wellbore structure determination method and preferred method of risk evaluation (see Figure 2) and so on.
Figure 1 catheter down into the depth of the design process
Figure 2 pressure information under uncertainty casing design process
Bomu-l Using this method JDZ Block Bomu-l wells body structure has been designed to the wells drilled after the detection of the formation pressure data and the actual drilling of its well structure stratigraphy assessment analysis carried out and the results of the analysis The second well casing structure optimization design, this cycle, so well structure gradually optimized.
3? the preferred method of deepwater drilling equipment
: Deepwater drilling equipment preferred key technologies are:
1) According to the drilling requirements and operating environments, various types of deepwater drilling units operating water depth rated, rated drilling depth, variable load size, self-propelled ability to adapt to the operating environment and seabed conditions and other performance characteristics analysis, combined with pre-drilled area water depth and drilling depth, determine the economic working depth and economic drilling depth:
Where: LE for economic working depth, m; LW location for the planned drilling depth, m; Dp for drilling platforms, drilling depth economic, m; Dd design depth of oil and gas wells, m.
2 to LE, and Dp is the basis of the drilling apparatus to comply with requirements and market economic assessment evaluation, and considering the operating environment and other factors and a certain amount of redundancy operation, and ultimately determine the type of drilling equipment.
4? the catheter into the next injection technology
Down into the catheter injection technologies include catheters pillar design, injection design and hydraulic parameters WOB design. ?? Catheter design appropriate column and preferably reasonable hydraulic parameters and catheter injection servant WOB key technology.
? Catheter pillar design based on subsea wellhead - Catheter column - stratigraphic mechanical model, the mechanical stability of the subsea wellhead protection from the perspective of the catheter strength checking, designed to meet the flexural strength of the catheter column combinations.
Hydraulic parameter design design principles are:
1) below the mud line of shallow drilling using high pressure water jet spray, the use of small diameter nozzle or jet velocity increases displacement to increase in order to achieve a direct effect of the jet rock breaking;
2) In order to avoid water jet near the wall of the catheter is too disturbed soil, reducing catheter down into the bearing after the drilling process to control the water jet rock breaking reaming diameter smaller than the catheter, which can not exceed the jet rock breaking displacement of most Jia displacement;
3) In order to improve portability rock drilling results, as far as possible the use of large displacement, in order to improve drilling fluid annulus velocity, but the calculation to be based on the maximum displacement fracture pressure in order to avoid pressure leakage strata;
4) when you need to consider the preferred displacement BHA drill motor, MWD tools such as the maximum allowable emission limits, typically 75L / s; 5), preferably water hole size should be considered in co-ordination with the drill bit size.
WOB design design principles: WOB servant is greater than the catheter resistance, to ensure the smooth catheter into the formation, less than string bending instability occurs aspect largest WOB yield failure to prevent the occurrence of the column.
5? well control techniques Deep wells are mainly preferred control key deepwater blowout preventer system, kick early detection, prevention measures and improved kill gas hydrate formation.
JDZ According to the actual situation of JDZ Block, recommend technical solutions as well control:
1) without taking into account the high level of the block, deepwater blowout preventer system chosen standard configuration, while monitoring is recommended PWD annulus pressure and circulation equivalent density to prevent annulus pressure is greater than formation fracture pressure and pressure leak strata;
2) scientifically determine the killing to prevent displacement due to a longer choke manifold caused friction caused by high pressure leak underground formations such as the occurrence of failure;
3)easy to form the deep borehole gas hydrate is recommended driller France killing, that is, first overflow cycle of the wellbore, shortening overflow in residence time within the wellbore while drilling gas hydrate inhibitor is added in order to minimize the formation of gas hydrates in the wellbore possibilities.
6?deepwater drilling fluid technology
Deepwater drilling are facing technical problems caused by low temperature rheology control difficulties caused by gas sand gas hydrate formation, shale stability, hole cleaning difficulties riser segment carrying rocks and poor environmental requirements higher. The study and learn from foreign major drilling contractor technical achievements made in addition to the catheter and surface segments using sea drilling, other well sections are drilling using synthetic based drilling fluid system, because the synthetic drilling fluid has both oil-based drilling fluids excellent performance, but also a better solution to the oil-based drilling problem of environmental pollution. Synthetic-based drilling fluid system is mainly based on synthetic base fluid (synthetic or modified organic matter) as the continuous phase, brine is dispersed, with emulsifiers, organic soil and other components. Deep cryogenic conditions, through the adjustment of the base fluid and emulsifier dosage to control and optimize the drilling fluid rheology, depending on the well section and stratigraphic drilling fluid properties can be added to the need for fluid loss agents, rheology modifiers, hydrate inhibitors and barite adjust system performance.
7? deepwater cementing techniques
The main challenges facing deepwater cementing grout is strength development at low temperatures slow, shallow stream invasion channeling, security density and narrow windows, which require performance by optimizing the slurry system and cementing technology two aspects to solve. ? Deep-water slurry system should have low water loss, short transition, strength, rapid development, WOC short time, etc., to be based on geological data, survey research neighboring blocks, using the optimal particle size distribution theory of optimal slurry system.
West African deepwater slurry system used bentonite slurry system with non-permeable cement slurry, etc., bentonite slurry system consisting essentially of class G cement, bentonite, early strength agent, non-permeable cement slurry consisting essentially of, non-permeate gas channeling agents, retarders, drag reduction agent. Cementing process should take full account of the pressure balance within the borehole to prevent leakage of fluid channeling and pressure underground formations such failure, and thus to real-time monitoring drilling parameters, slurry rheology data, through software simulations to ensure that the cement pulp properties, cementing operation parameters satisfy the equilibrium pressure of the whole process of cementing requirements, while optimizing performance and the amount of pad fluid, improve the displacement efficiency and achieve concrete ring packer long term.
Third, field application and effect analysis
Since 2009, Sinopec to the identity of the job done in Nigeria JDZ Block 5 saliva deeper than 1 600 m of exploratory well, not only effectively promoting the JDZ Block deepwater oil and gas exploration and progress, and achieved a breakthrough in oil and gas exploration, as Sinopec increase reserves and production to make a certain contribution. ? In addition, the technology also successfully applied to Nigeria, Angola and other West African deep waters, resulting in huge economic and social benefits.
Bomu-l? Bomu-l Sinopec as well is the first operator to complete Estuary wildcats, operating depth of 1 655 m, design depth of 3 558 m, the actual drilled deep 3 580 m, the actual construction cycle 44.16 d, than the design construction cycle shorten 6. 27 d, save and invest more than 7.5 million U.S. dollars. The well is now an example to the application of the technology.
1, the choice of drilling equipment
Bomu-l?? Consider long-term rig contracts operator's job gap, through analysis and comparison and economic evaluation, the final selection of the company's Sedc0702 Transocean dynamic positioning semi-submersible drilling rigs Bomu-l wells. ? The drilling platform operating water depth 2 000 m, drilling depth 7 700 m, fully meet the Bomu-l wells drilling needs, and can complete the drilling of the first exploration period workload and direct hire equipment compared to other contractors can save 700 - 10 million dollars.
2? shallow hazard evaluation and control of the identification
? Shallow hazard to effectively identify, in Bomu 1 Ibara near wells dedicated to the acquisition and processing of seismic data interpretation, the results shown in Figure 3.
?3 JDZ-2 Figure 3 JDZ-2 seismic profiles (partial) and comparison of old and new wells
As can be seen from Figure 3, the original depth of wells 1 928 m (mud line 293 m) at a plurality of seismic section amplitude anomalies, analysis highlights where the airbag is displayed as in the form of high-pressure gas in the formation. ? To this end, the original design wells was changed to avoid shallow gas area, so as not to shallow gas drilling harm? In neighboring blocks certain wells drilled prior to failure due to more accurately identify shallow gas and risk assessment, the process of drilling the surface hole section drilled more serious and cause shallow gas blowout, resulting in drilling equipment by loss, formation collapse and eventually had to replace the re-drilled wells, the direct economic loss of nearly ten million U.S. dollars.
3 casing design
Combined with the actual geological conditions, design Bomu-l well casing structure: ø762.O mm duct jet down to below the mud line 83 m; ø660.4mm drill bit with the main purpose to Tl layer on top of layer 58 m, down ø508. O mm casing; using ø311.1 mm drill bit to T2 layer under the Ministry of drill completely main target; if ø311.1 mm drilled hole section can not be expected to horizon, then the well section reaming to ø444.5 mm, then the next ø339.7 mm casing, then ø311.1 mm drill bit to the design horizon, under ø244.5 mm casing; finally ø215.9 mm drill bit to the final design depth of 3 558 m drilled.
Bomu-l 580.O Bomu-l Well Drilling real body structure: ø762.O mm duct jet down to below the mud line ø108.6 m, with ø660.4 mm drill bit to the main target Tl layer on top 45.O m, with ø311. 1 mm drill bit to a depth of 3108.4 m, servant ø244.5 mm casing, then ø215.9 mm drill bit to a depth of 3 580.O m drilled. Visible, the design and implementation of the drilling hole structure body structure agrees well drilling process does not occur due to structural design of wellbore instability caused by an irrational wellhead and downhole failures. . 62 kg/L, In neighboring blocks of a well casing structure is not reasonable because, drilled to a depth of 4 489 m kick occurs, the job will be drilling fluid density to 1. 62 kg / L, resulting in a depth of 4 257 m and 4489 m occurs at more severe lost circulation, greatly increasing the cost of drilling.
4?the catheter injection into the next
Bomu-l?? Bomu-l wells using a combination of the catheter column in Table 1.
?1 Bomu-1?????? Table 1 Bomu-1 well composed catheter column
762.0 .3~25.4 mm,??6.25 L/68. 75 L/s? ø762.0 mm catheter column uses ø660.4 mm drill down into the jet, water hole size is 14.3 ~ 25.4 mm, first with 6.25 L / s, small-displacement drilling, and then slowly increased to 68. 75 L / s. ??? Through underwater robot (ROV) was observed to ensure cuttings ø762.O mm catheter back out, back out of the catheter, has no debris. ? WOB gradually increased from O to 454 kN, primarily through the drill pipe string below the mud line to control its own gravity WOB kept above the mud and drill pipe conduit is vertically stretched state, that is to maintain neutral point below the mud line . Site construction process, recommended WOB WOB is consistent with the actual construction process without duct bend, servant blocked, fluid outside back, wellhead instability and other downhole failures.
5? 5, fluid technology
Bomu-l? Bomu-l wells ø762.O mm and ø660.4 mm hole section using sea water and sea water / cleaning fluid viscous drilling, are directly discharged to the sea floor; due ø311.1 mm and ø215.9 mm hole section mudstone Yasumizu of expansion, causing collapse, tripping, etc. Difficult downhole failures, so the use of oil-water ratio of 76:24 of synthetic-based drilling fluid system. Bomu-l? Bomu-l wells drilling indicates that the system has good lubricity and inhibition, low and high temperature to maintain good rheological properties of drilling well, well diameter rules can satisfy the geologic and engineering requirements.
6, deepwater cementing
Bomu-l? Ø508.O mm Bomu-l well casing cementing method using internal pipe cementing collar pulp density of 1. 44 kg / L, an additional amount of 150% of the volume of the naked eye, the tail rotor density of 1.90 kg / L, additional amounts of to 50% of the volume of the naked eye, and brought back to the seafloor mud slurry line, tail rotor back to the shoe over 152.4 m, so that can ensure that the water mud returns to the sea, but also to ensure that the cementing casing shoe quality assurance follow-up work carried out smoothly. ø339.O ø339.O mm casing cementing plug cementing the underwater release. ø244.5 .5 mm casing cementing collar pulp density of 1.50 kg / L, an additional amount of 50% of the volume of the naked eye, the tail rotor density of 1. 90 kg / L, an additional amount of 50% of the volume of the naked eye, and brought back to the slurry T1 layer on top of 152.4 m (depth 2 279.9 m or so), the tail rotor back to the shoe above the 152.4 m, cementing touch pressure is 4 MPa, water, mud returns to a predetermined depth.
Conclusion:
Depending on the West African deepwater exploration and development needs of deepwater drilling and completion techniques to carry out research studies, initially forming a shallow hazard identification and control, structural optimization wellbore, deepwater drilling equipment preferred catheter injection into the next, deep wells control , deepwater drilling and deepwater cementing key technologies such as drilling and completion, and successfully applied to Nigeria, Angola and other West African deep waters, effectively promoting the overseas oil and gas exploration and development in the petrochemical project progress, resulting in a good economic and social benefits.
China Sinopec JDZ Block as an operator has successfully completed five deepwater well construction, where the operating water depth of 1 655m Bomu-l of oil wells is completed as the first port operator deep wells, oil drilling in our country history of great significance.
? This not only enhances the China Petrochemical deepwater oil and gas exploration and development to further increase the confidence of investors, but also for Chinese enterprises to participate in domestic and international deepwater oil and gas exploration and development has played an exemplary role in promoting.
deepwater drilling in China is still in its infancy, has formed the drilling and completion techniques need to be further improved and increased application of force.
Recommended depth deepwater drilling and completion key technology research, in particular to carry out the theory and key technology of deepwater completions, drilling and completion equipment and tools, research studies and standardization of the prior art to form a supporting deepwater drilling and completion techniques, and further reduce operating costs, so that our deepwater drilling and completion technology standards to meet and exceed the international advanced level, to promote deepwater fast, economical and effective exploration and development.
Lu Bao Ping / China Petrochemical Petroleum Engineering Technology Research Institute)
China Sinopec International Petroleum Exploration and Development Corporation
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