Lithoselatium tantichodoki, a new species of intertidal crab (Crustacea:Brachyura: Sesarmidae) from southern Thailand

A new species of intertidal sesarmid crab, Lithoselatium tantichodoki new species, is described from the Gulf of Thailand. The species is superficially similar to L. kusu Schubart, Liu & Ng, 2009, from Singapore and Malaysia, but differs in the proportions of the ambulatory legs and the structure of the male first gonopod.

Three new species of Sternaspidae (Annelida: Sedentaria) from Thailand

In this contribution, three new species of sternaspids collected from sediments along the coast of southern Thailand are described: Petersenaspis apinyae sp. nov. from a depth of 50–80 m offshore in the Gulf of Thailand; P. narisarae sp. nov. from 9 m depth in the Songkhla Sea, Gulf of Thailand; and P. pakbaraensis sp. nov. from tidal mudflats on the Andaman Coast. All three species resemble P. palpallatoci Sendall & Salazar-Vallejo, 2013. They differ mainly in the pigmentation and shape of the shield, the number of ventral chaetae and chaetae at the posterior shield, body papillae, and size of the abdomen. Further, P. apinyae sp. nov. is clearly distinguished from other species of the genus by having dark orange to red butterfly wing-shaped shields, with strongly curved anterior margins. P. narisarae sp. nov. differs from other species by having concentric colored bands over shields and an expanded oval abdomen. P. pakbaraensis sp. nov. can be distinguished from other species by its dark brown-purple shield and laterally expanded fan. These three species have a unique character in their branchial plates: long brownish filaments. A key to the identification of all species of Petersenaspis is included.

Enabling Extended Reach Wells with the Aid of an Ultra-High Speed Rotational Reamer Shoe

Well X is an infill horizontal well designed for the Gulf of Thailand. It is challenging due to the following factors - A long 8 ½ inch open hole section, An extended reach section at horizontal or near horizontal, the presence of loss circulation zones, an Extended Reach Drilling (ERD) ratio of 2.725 and a Drilling Difficulty Index (DDI) of 6.762. The key challenge was to successfully deploy the 7 inch casing across 12,350 ftMD of open hole, with potential loss circulation zones. In spite of these difficulties, the 7 inch casing was successfully landed with the use of an Ultra-High Speed Rotational Reamer Shoe. Historically, losses of circulation have posed significant challenges to well delivery in the Gulf of Thailand wells. In Well X, this is further complicated by a long open-hole section with a step-out of over 10,000 ftMD. It was determined that the successful deployment of the 7 inch casing would require some degree of agitation at the nose, and such a device must be tolerant to the Lost Circulation Materials (LCM) type and the composition of the drilling fluid and the cement. An ultra-high speed rotational reamer shoe was specially configured to meet the LCM requirements in the displaced fluid, for use in deploying the casing. While deploying the 7 inch casing, losses of up to 20 bbls/hr occurred from 7,043 ftMD while running at 15 joints/hr. A loss circulation recipe comprising of 60 bbls of 30 ppb Tiger LCM was mixed and successfully displaced through the customized ultra-high speed reamer shoe to cure losses. The casing was washed down from 10,569 to 11,610 ftMD, filling casing each stand. The 7 inch casing was successfully landed at the target depth of 12,353 feet and subsequently cemented. Drill out operations took 1.5 hours to complete. A formation integrity test (FIT) showed good shoe strength which was later confirmed by the cement evaluation logs. The comprehensive Ultra-High Speed Reamer Shoe was configured with a minimum restriction of 15mm, which is 5 times the diameter of the maximum particle size in the LCM of 3 mm. The tool was designed to tolerate the prescribed loss circulation materials, making it possible to cure the losses while running the casing string. The innovative Ultra-High Speed Reamer Shoe has demonstrated its usefulness by providing a higher probability for successfully deploying the 7 inch production casing over the extended reach section of Well X. The application of this technology can mitigate against non-productive time such as wiper trips or excessive washing down or casing rotation. It has proven to be a reliable technology that can be used in the industry in challenging well designs.

Sedimentary History of Trace Metals Over the Past Half-Century in Songkhla Lake, Western Coast of the Gulf of Thailand: Anthropogenic Impacts and Contamination Assessment

Coastal lagoons are among the most vulnerable and economically significant ecosystems on Earth. Songkhla Lake, connected with the Gulf of Thailand, is the second largest lake in Southeast Asia and supports the development of the fishery, transportation, and tourism industries in southern Thailand. With increasing anthropogenic disturbances, the lake is facing acute ecological problems and further research is needed. Here, we provide 55-year record of grain size, color reflectance, magnetic susceptibility, total organic carbon, total nitrogen, and trace element (As, Hg, Pb, Cr, Ni, Cu, and Zn) concentrations of sediment core SKL8-2 collected from Songkhla Lake. These records reveal a three-stage sedimentary and input history of trace metals under anthropogenic effects: 1) From 1964 to 1982, it was a natural terrigenous input period with a relative reduction environment when the channel connecting Songkhla Lake and the Gulf of Thailand was closed. 2) Trace metal concentrations, organic carbon content, b* value, and magnetic susceptibility changed abruptly in 1982. During 1982–2000, the sources of trace metals were more complex than during 1964–1982 and mainly came from urban wastewater, industrial effluent, and fishery discharge. 3) From 2000 to 2019, contamination signals of Pb, Hg, As, Zn, and Ni emerged in the first decade because of the rapid development and poor sewage treatment around nearby cities.

Pipeline Decommissioning: Comparative Study of Pipeline Corrosion in the North Sea and the Gulf of Thailand

The long-term degradation of decommissioned pipelines left in situ is an important topic in decommissioning projects. These constitute a long-term health and safety challenge in the form of snagging risk to other users of the sea. An accurate forecast of the long-term behavior of the pipelines in the marine environment would allow to make an informed decision regarding the feasibility of leave in place option for pipeline decommissioning. This paper aims to summarize the effect that individual environmental factors in marine corrosion have on the corrosion rate and to discuss in detail a chosen corrosion model that could be used to predict the long-term corrosion of in situ decommissioned subsea carbon steel pipelines in the marine environment. In addition, the long-term degradation will be predicted with the chosen corrosion model and the results will be compared for a range of subsea pipelines to be decommissioned in the North Sea and the Gulf of Thailand. With the chosen corrosion loss model, considering the higher average annual seabed temperature in the Gulf of Thailand in comparison with the North Sea, the predicted long-term corrosion rate of unprotected carbon steel is 0.053 mm/y for the North Sea and 0.069 mm/y for the Gulf of Thailand.

Four new species of Pilargidae (Annelida: Pilarginae) from the Gulf of Thailand

Four new species belonging to the Family Pilargidae, Ancistrosyllis kornkanokae sp. nov., A. nakkaritae sp. nov., Cabira saithipae sp. nov., and C. thailandica sp. nov. were collected from 9–27 m depth in soft sediments in the Songkhla Sea, Gulf of Thailand. Ancistrosyllis kornkanokae sp. nov. can be distinguished from other species in the genus by the presence of a small median antenna on the prostomium; two pairs of elongate tentacular cirri; and short limbate neurochaetae with unidentate curved pointed tips. Ancistrosyllis nakkaritae sp. nov. is characterized by having a conspicuous median antenna and elongate lateral antennae longer than palps; and short limbate neurochaetae with bifid tips. While Cabira saithipae sp. nov. is characterized by the presence of the first notopodial hook at chaetiger eight, large, conical papillae ont chaetigers 7–17 and the presence of both short, recurved tipped and short, curved tip chaetae in anterior chaetigers. Cabira thailandica sp. nov. is distinguished from other species in the genus by the first notopodial hooks occurring at chaetiger seven and the presence of long, non-limbate capillary neurochaetae with bidentate tips. Updated keys to the genera Ancistrosyllis and Cabira are also provided.