Deepwater Exploration Wells Research Articles

Analysis of the world oil and gas exploration situation in 2021

The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries; second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly; third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins; fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.

Depth Influencing Factors and Coping Techniques of Logging and Logging while Drilling in Deep Water

Aiming at the influence of tide, wave, ocean current and drilling engineering on logging and logging while drilling depth system and cuttings lag depth, the methods of equipment-related professional sensors, physical indicators, controlling drilling parameters and proofreading in drilling process are used to achieve the purpose of collecting all kinds of geological data in the harsh deep water environment. It is of guiding significance to ensure the accuracy of geological related data in deep-water exploration operation. At present, many deep-water exploration wells in the eastern South China Sea have achieved good results.

Petroleum geology controlled by extensive detachment thinning of continental margin crust: A case study of Baiyun sag in the deep-water area of northern South China Sea

Abstract The relationships between crustal stretching and thinning, basin structure and petroleum geology in Baiyun deep-water area were analyzed using large area 3D seismic, gravity, magnetic, ocean bottom seismic (OBS), deep-water exploration wells and integrated ocean drilling program (IODP). During the early syn-rifting period, deep-water area was a half-graben controlled by high angle faults influenced by the brittle extension of upper crust. In the mid syn-rifting period, this area was a broad-deep fault depression controlled by detachment faults undergone brittle-ductile deformation and differentiated extension in the crust. In the late syn-rifting period, this area experienced fault-sag transition due to saucer-shaped rheology change dominated by crustal ductile deformation. A broad-deep fault depression controlled by the large detachment faults penetrating through the crust is an important feature of deep-water basin. The study suggests that the broad-deep Baiyun sag provides great accommodation space for the development of massive deltaic-lacustrine deposition system and hydrocarbon source rocks. The differentiated lithospheric thinning also resulted in the different thermal subsidence during post-rifting period, and then controlled the development of continental shelf break and deep-water reservoir sedimentary environment. The high heat flow background caused by the strong thinning of lithosphere and the rise of mantle source resulted in particularities in the reservoir diagenesis, hydrocarbon generation process and accumulation of deep-water area in northern South China Sea.

Salt tectonics along the Atlantic margin of Morocco

Abstract The Moroccan salt basin appears to be very unique in the sense that it is not sedimentary loading but tectonic inversion which appears to drive the latest stages of salt-related deformation in the central part of the basin. The gravity potential to maintain salt tectonics is provided by the differential uplift of the Atlas Mountains, located adjacent and striking almost perpendicular to the margin. Along the offshore part of the Moroccan salt basin there are many play types, most of them related to the Triassic syn-rift salt. Toe-thrust anticlines at the basinwards edge of the salt basin form very large structures. Traps associated with salt tongues and diapirs define a more ‘classical’ salt-flank play. Numerous salt tongues, sheets and canopy complexes provide for a ‘Gulf of Mexico-style’ subsalt play. Despite the numerous untested play types, there have been only four deep-water exploration wells drilled in the entire Moroccan salt basin, none of them having subsalt penetrations.

Improving team effectiveness using tactical decision games

This paper addresses the development of training in team-level decision making to lead to improvements in safety and performance. A one-day Workshop was developed around tactical decision games (TDGs) for use by action teams, i.e. involving a team of multi-disciplinary experts, in the oil and gas drilling industry. Three TDGs were conducted to help team members to rehearse how they would respond to potential challenging situations, focusing in particular on team skills, such as decision making, situation awareness and communication. TDGs have previously been presented as a useful training technique to improve decision making and have been introduced in many high hazard industries [Crichton, M., Flin, R., Rattray, W.A., 2000. Training decision makers – tactical decision games. Journal of Contingencies and Crisis Management 8(4), 208–217]. Building on TDGs for individuals, in a team-based TDG, team members discuss the scenario and reach a team-based solution, allowing team members to recognise the potential differing perspectives brought to the solution by team members from different disciplines. Specific team skills aspects raised during the TDG scenario were then generalised to the wider project, and their impact on overall team performance, safety, and effectiveness. Members of a deepwater exploration wells team ( n = 30) attended the Workshop and reported that the use of TDGs in the Workshop was valuable in defining and illustrating team skills and their influence on team performance, and helping to prepare better for their forthcoming operations.

The prospectivity of the Vøring and Møre basins on the Norwegian Sea continental margin

The focus of exploration activity on the Norwegian Sea Continental Shelf has shifted westwards from the shallow water areas over the Trøndelag Platform and Halten Terrace to the deep water areas over the Cretaceous Vøring and Møre basins. The basins, especially the Vøring Basin, have been involved in a complex tectonic development since the main extensional phase in the late Middle Jurassic to Early Cretaceous, including Cenomanian–Campanian and Maastrichtian–Eocene extension and thermal uplift and intermittent phases of compression/transpression. While the Jurassic is the prospective interval in the Trøndelag Platform and Halten Terrace, the potential in the Vøring and Møre basins is seen mainly in the Cretaceous and Paleocene – the Jurassic is too deeply buried. The two first deep water exploration wells in these basins, 6707/10-1 and 6305/5-1, have already proven two effective plays, with excellent reservoir sands in the Upper Cretaceous and lower Paleocene charged with thermogenic gas in structural traps in rotated fault blocks and compressional domes. Palaeogeographical reconstructions indicate that these reservoir rocks may be widespread within the basin areas. No good oil-prone source rock at a suitable depth of burial is so far proven, but the palaeogeographical reconstructions linked to surrounding well data and regional analyses indicate a chance for the existence of Upper Cretaceous oil source intervals. The thermal history of the basins is as complex as their tectonic history, and is further complicated by the possible effects of the Paleocene–Eocene magmatic activity, making any basin modelling results at the present stage unreliable.

Hydrate Inhibition Design for Deepwater Completions

Summary This paper will review the design considerations for gas hydrate prevention in deepwater well completions. The influence of seafloor temperature, wellbore pressure, water production rate and composition of gas on hydrate inhibition system design will be discussed. The impact of various inhibitors will be discussed in relationship to the design of the system and potential handling problems. Examples will review design considerations for sizing of subsea inhibitor lines, selection of injection depth below the seafloor and hardware requirements. Case histories of inhibitor injection systems used in deepwater completions and during testing of deepwater exploration wells will be reviewed. The benefits of insulated tubing to enhance inhibition design will be discussed. Also, a method will be introduced that can be used to estimate the maximum inhibitor injection rate to avoid salt precipitation from completion fluid or produced water.