Abstract
In this paper, to solve the problems of low water absorption and weak pressure bearing capacity of current plugging materials, acrylic acid (AA), acrylamide (AM), and sodium allyl sulfonate (SAS) are used as monomers, and soluble starch is used as grafting. Material, the use of free radical aqueous solution method to synthesize the plugging agent SWL-1 with good water absorption and strong salt resistance. The monomer ratio is set as n (AA):n (AM):n (SAS) = 5:2:1, the experimental synthesis temperature is 70°C, and the orthogonal experiment is used to determine the experimental synthesis conditions as AA neutralization degree 80%, The amount of initiator is 0.60%, the amount of crosslinking agent is 0.50%, the ratio of monomer to starch is 7:1, and the amount of calcium carbonate is 13%. The comprehensive evaluation of the performance of the plugging agent SWL-1 shows that the water absorption performance at 60°C is the best 268.78 g/g, and the water absorption performance in 8% NaCl, 0.9% CaCl2 and composite brine is 21.5 g/g, 12.5 g/g and 24.9 g/g, indicating good resistance to sodium and calcium, the water retention rate is still higher than 30% after 15 days at 160°C. The sand bed plugging test found that the maximum pressure of SWL-1 was 7 MPa, and the crack plugging test found that when the crack width was 1 mm, 2 mm, and 3 mm, the maximum compressive strength of SWL-1 was 10 MPa. The acid solubility test showed that the maximum pressure was 10 MPa. The highest rate is 86.38%.
Highlights
The comprehensive evaluation of the performance of the plugging agent SWL-1 shows that the water absorption performance at 60 ̊C is the best 268.78 g/g, and the water absorption performance in 8% NaCl, 0.9% CaCl2 and composite brine is 21.5 g/g, 12.5 g/g and 24.9 g/g, indicating good resistance to sodium and calcium, the water retention rate is still higher than 30% after 15 days at 160 ̊C
Since the plugging agent is produced by the reaction of soluble starch, monomers, cross-linking agents, initiators and other substances, the development of the plugging agent requires many factors to consider [17] [18] [19] [20], and the monomer ratio is set as n (AA):n (AM):n (SAS) = 5:2:1, the experimental synthesis temperature is 70 ̊C, the dosage of initiator, monomer starch ratio, crosslinker and neutralization degree of acrylic acid (AA) were changed, the orthogonal experiment of the experiment is set to L9(34), to find an optimal experimental condition, Get the best performance plugging agent
M1 is the mass of the plugging agent before water absorption, and m2 is the mass of the plugging agent at a certain time at a certain temperature after water absorption
Summary
Loss damage to the oil layer is reflected in the damage to the oil layer and the decline in oil production, and the prolonged drilling cycle, the loss of drilling fluid, completion fluid and other working fluids, loss of plugging materials, interference with geological logging, etc. It will cause well collapse, sticking, and in severe cases, the wellbore will be scrapped [6] [7] [8] [9] [10]. A water-swelling plugging material SWL-1 was prepared indoors, and its performance was evaluated
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