Non-Toxic High Temperature Polymer Drilling Fluid Significantly Improving Marine Environmental AcceptabiIity and Reducing Cost for Offshore Drilling

Abstract

Oil based drilling fluids, polysulfonate and other toxic drilling fluids have been restricted to use by strict environmental protection laws and regulations, when drilling in high temperature well in environmentally sensitive sea areas. Meanwhile, the environmental requirements of drilling fluid biological toxicity value LC50 greater than 30,000mg/L, Hg content of barite less than 1mg/L and Cd content less than 3 mg/L, which brings severe challenges for high temperature drilling fluids and offshore environmental protection. A kind of new non-toxic and high temperature polymer drilling fluid with the temperature resistance for 200°C and the biotoxicity value satisfied the discharge standard of the first class sea area has been developed in order to meet the requirements of high temperature deep well drilling operation and environmental protection. It can also drastically reduce the costs of waste disposal that is due to the drilling fluid and drilling cuttings can be discharged directly to the sea. A high temperature polymer filtrate reducer with temperature resistance for 200°Cand viscosifier with temperature resistance for 180°C both have been developed, which are used for high temperature filtration control and rheology regulation. This new system consists of these two high-temperature synthetic polymer materials, along with a special nano-plugging agent, glycol shale inhibitor, extreme pressure lubricant, and barite or formate weight materials. The formula and performance of drilling fluid are studied which suitable for drilling under different formation pressure coefficients, and the performance of drilling fluids at different bottom hole temperatures are also reviewed, so as to prove it can provide superior fluid performance for various harsh drilling conditions. The test results showed that the drilling fluid has the following main technical features: temperature resistance for 200°C, 200°C thermal stability time more than 72h, HTHP water loss 15~25mL, aquatic biological toxicity LC50 value higher than 100,000mg/L, luminescent bacteria EC50 higher than 300,000 mg/L. The test results from a high temperature deep well in Bohai offshore oil field, with depth of the bottom well 6066m, and the bottom temperature 204°C, are also presented. This drilling fluid is environmentally friendly and meets the discharge requirements of offshore, which can greatly improve the HSE operation level and eliminate the rig costs associating with drilling and waste management, especially in remote sea and deep sea drilling, that the disposal cost of waste drilling fluid accounts for more than 30% of the total drilling fluid cost.

Microplastic Extraction from the Sediment Using Potassium Formate Water Solution (H2O/KCOOH)

“…The other important reason to use them, apart from their good performance in a wide range of conditions, comes from the positive parameters in terms of the toxicological and ecotoxicological properties of KCOOH [37]. Drilling fluids based on (H 2 O/KCOOH) and containing synthetic polymers, have been classified as temperature resistant (up to 200 • C) and meeting biological toxicity discharge requirements/criteria for the first level sea area [38] KCOOH is also being used in the design of water harvesters as a non-corrosive and more environmentally friendly alternative [39] (Ayyagar et al, 2021). The non-corrosivity is additionally important because in plastic research all the equipment used for experimental needs to be plastic free and is thus often made of steel.…”

Nanomaterial-Based Drilling Fluids for Exploitation of Unconventional Reservoirs: A Review

“…Drilling fluid engineers are required to resolve these challenges and provide solutions by finding adequate fluid formulations of good continuous performance in all adverse condition [39]. The drilling fluid system not only preserves favorable rheological properties at high temperature, but also balances drilling fluid weight to contain formation pressure with minimum invasion.…”

“…Some natural polymers, in particular guar gum, starch, and cellulose, have been successfully used alongside bentonite to achieve adequate drilling fluid properties [37]. Naturally available polymers have been widely used due to their low cost [38], and environmentally friendly nature [39]. Nonetheless, natural polymers have low temperature stability [40][41][42].…”

Preparation of Ultra-High Temperature Resistant Cyclodextrin-Based Filtration Loss Reducer for Water-Based Drilling Fluids

“…These groups allow the polymers to chemisorb onto clay particles, independent of temperature. Ban et al [ 45 , 46 ] prepared an organosilicon filtration loss reduction agent (AATN) that can withstand high temperatures up to 180 °C. This agent effectively wraps around the bentonite and reduces the filtration loss of drilling fluids by forming a chemisorption layer.…”