Shape Memory Polyurethane as a Drilling Fluid Lost Circulation Material

Abstract

Drilling fluid loss is a major problem with serious economic and environmental consequences. The use of traditional lost circulation materials (LCMs) to seal wide fractures increases the risk of bit nozzle plugging. In this work, smart LCMs based on shape memory polyurethane (SMPU) are proposed for the first time. SMPU can be programmed to recover at temperatures suited to a given well. As such, SMPU smoothly passes through the bit nozzles, while effectively seal wide fractures once activated. The SMPU is prepared by two step pre-polymerization and characterized by Fourier transform infrared spectra, X-ray diffraction, and differential scanning calorimeter. The SMPU is programmed by changing and fixing the original shape to a temporary shape through a thermo-mechanical process. The shape memory behavior of SMPU is analyzed by tensile apparatus. Compatibility of SMPU with WBMs is determined from mud rheology and filtration tests. Fracture sealing efficiency and shape recovery of SMPU are evaluated by a modified particle permeability apparatus fitted with a model fracture. The results confirm high sealing and shape recovery attributes of SMPU. The plug formed at 114 kg m -3 SMPU and 80 °C experiences a sealing pressure of 100 bar with 71.5 cm 3 cumulative fluid loss.

Research Progress of Elastomer Materials and Application of Elastomers in Drilling Fluid

“…Drilling fluid leakage into fractures is a challenging problem, which can lead to high-cost drilling and formation damage. Lashkari et al [ 80 ] used conventional LCM to seal wide fractures, which increased the risk of bit nozzle clogging. Thermoplastic SMPU LCMs with a molar ratio of 21: 20: 1 of HDI, BDO and PCL were synthesized by two-step repolymerization using PCL with a molecular weight of 22711 (g·mol −1 ) as a soft segment.…”

A temperature-sensitive plugging material composed of shape memory polymer and self-made gel

“…The problem of leakage is inevitable during the process of oilfield development. According to different rate of leakage, it can be divided into seepage loss(<1.6 m 3 h −1 ), partial loss(<1.6-80 m 3 h −1 ), and total loss (>80 m 3 h −1 ) [1,2]. When leakage occurs in the wellbore, it will lead to the continuous leakage of drilling fluid into the formation, resulting in a large amount of raw material cost loss, and serious leakage will directly cause construction interruption [3,4].…”

“…Gel could be a proper choice when dealing with the leakage of small fracture, since gel can fully enter the interior of fractures, and low pressure from fluid impact [27]. Therefore, we hope to apply the advantages of SMP and gel to seal the leakage [28,29]. The high temperature of formation can act on the SMP and pregel at the same time.…”

Novel smart plugging material for high‐temperature gas well

“…The complex formation brings severe challenges to conventional plugging materials and puts forward higher requirements for temperature resistance, compressive strength, and retention capacity of plugging materials 4–6 . For the development of lost circulation materials for high‐temperature gas wells, series of works have been developed, mainly focusing on gel and temperature‐sensitive shape memory materials 7–18 …”

“…[4][5][6] For the development of lost circulation materials for high-temperature gas wells, series of works have been developed, mainly focusing on gel and temperaturesensitive shape memory materials. [7][8][9][10][11][12][13][14][15][16][17][18] Bai et al [19][20][21] have developed a gel plugging material with temperature resistance up to 160 C based on the adhesive plugging characteristics. The storage modulus is up to 60 Pa. Mansour et al 22,23 first proposed the intelligent temperature-sensitive shape memory plugging material, which can expand under high-temperature environment, improve the plugging efficiency of fracture formation, and has a good wellbore strengthening effect.…”