Research On Foam Fluid Properties And Effect Of Cuttings On Foam Drilling Fluid Stability

Foam fluid is widely used in some special stratum such as Low-pressure, leakage and water-sensitive stratum for drilling, completion, workover and production of oil and gas wells (such as foam drainage, vacuum sand washing, etc.), due to its low static fluid column pressure, small amount of fluid loss, good carrying sand performance, strong ability to drainage and small damage to stratum. Just because foam fluid has these advantages, domestic and international drilling workers are increasingly attached great importance to it. The theory and the technology of foam drilling get a rapid development. The history of researching on foam fluid is about 30 years; it was used in practice and has achieved some results.Foam fluid is a special kind of colloidal dispersion system; it is formed by soluble or insoluble gas dispersed in the liquid. Foam fluid can widely used in drilling engineering and other geological engineering, its stability as a prerequisite for application by the attention of the people.This text investigates the domestic and international foam fluid theory, following and absorbing domestic's latest research result of the theories concerning the foam. Foundation investigate in a great deal of cultural heritage up, expatiate the definition, configuration formation process and the main performance. Introduce some familiar vesicants and their mechanism of foaming. From three aspects: the molecular structure of vesicant, the concentration of vesicant and other additive in vesicant, discussing the effect on the foaming ability of vesicant. Analyze theoretically in two mechanisms on foam breaking: the loss of liquid in foam fluid and the diffuseness of gas through the liquid membrane, in the basis of these mechanisms, some main factors which effect on the stability of foam drilling fluid are discussed.The Waring Blender mixing method was used as the evaluation method in the experiment which about properties of foam drilling fluid in this test. This method is simple and feasible, less drugs dosage, short test cycle and the use conditions is unrestricted (indoor and the field can be).First or all, making use Waring Blender mixing method to research the effect on foaming ability and stability under the condition of different temperature, concentration and time length.Based on the experimental results, we can observe the relationship between foam volume, the half-life and these factors, at the same time, make some analysis on this relationship in theory. Finally, some laws are summarized as follows:(1)As the temperature increases, the foam volume gradually increase, when the temperature rises to 140oC, the foaming ability begins to decline. The half-life decrease with the rising of temperature, that is, with the increase of temperature, the stability of foam fluid is getting worse.(2)The concentration of vesicant has a greatly impact on the foaming ability and half-life. With increasing concentration of vesicant, the expanding property and half-life increase to the maximum, then begin to reduce or stabilize.(3)The longer time foam fluid is deposited, the smaller foaming volume and half-life of foam drilling fluid, and the worse property of foam drilling fluid become.With the same method, we can measure the foaming volume and the stability time (half-life) of foam drilling fluid under the conditions of different diameter of cuttings and different concentration of cuttings. According to the results of experiment, we can get the evaluation and summary, educing the relation between cutting diameter, cutting concentration and the properties of foam drilling fluid. In addition, the reasons for these results were discussed.In the experiment of the foaming volume and half-life about cuttings diameter, AES is vesicant and sandstone cuttings as an example. The diameters of cuttings are separately 5 mesh, 10 mesh, 50 mesh, 100 mesh, 150 mesh and 200 mesh. The results of experiment indicate that the larger cutting diameter is, the larger the foaming volume and half-life become, But if the diameter is too large, cuttings will not be carried by the foam drilling fluid, and the foam drilling fluid will be lost its own action.In the experiment of the foaming volume and half-life about cuttings concentration, the cutting of limestone, sandstone and shale were used, an effective solution is used which provided by a company, its ingredient is H2O+0.4%CMC+0.1%clay+0.5%SDS(or AES), The results of experiment indicate that for SDS vesicant, when the cuttings concentration of limestone, sandstone and shale is separately 0.4%,0.8%and 0.6%, the foaming volume and half-life were reached maximum; for AES vesicant, when the cuttings concentration of limestone, sandstone and shale is separately 0.4%,0.8%and 1.0%, the foaming volume and half-life were reached maximum.In addition, do some research to antifoaming and the recycling and reuse. On antifoaming, introduce a physical method, including its equipment and structure of Principle. Test the antifoaming effects under different pressure and different air velocity with antifoaming equipment, at the same time, evaluating the effect of antifoaming. The experimental results show that antifoaming efficiency can be up to 70 percent using this equipment, and meet the basic requirements of antifoaming in actual production. However, in order to promote this technology and equipment applications better, we need do the further study to this equipment, so that getting a better effect. Because the foam drilling fluid is hard to recycle and reuse, a kind of technology for recycling and reuse is introduced, Through the use of this technology, solve the repeated use of one-time foam drilling fluid and save the cost.