Research On Plant Glue Drilling Fluid Medium Application In Fracture And Karst Strata

Foam fluid drilling technology had been applied widely, especially in the arid areas or broken formation during drilling, it was becoming a common construction technology, the application of those study were also carried out many. The overall train of thought about this paper was in Hunan water or rich water karst fissure formation region, combined with foam fluid drilling technology characteristic, the paper proposed plant glue drilling fluid medium concept, the plant gum foam medium preparation and drilling technology had studied, and the applications in engineering aspects of the site practice, and achieved good results.After studying on the basic characteristics of the fracture karst stratum in Hunan and analysising its formation mechanism, the paper summarized the fractured formation, cave formation and fragmentation and collapse type formation in three categories, and the influence of stratum leakage channel was formed in the opening, spacing, roughness, connectivity and filling five main factors elaborating, of the formation is easy to produce the loose, swelling, peeling, erosion and borehole wall instability and missing of the well drilling liquid drilling features were described. In the karst developing features of karst growth process that has level sex, synchronization, persistence, periodic and repeatability characteristics, its formation mechanism main performance is: mechanical creep collapse, gravity collapse, vacuum suction erosion effect collapse, collapse and chemical gas explosion dissolution collapse.Its drilling was characterized mainly by the drilling fluid leakage or diluted, Kong Biyi collapsed, prone to hole drilling accident. This paper comprehensively discussed the karst fissure formation drilling technology and wall protection and leaking stoppage technology. Combined with the formation characteristics, the" card, bury, burn drill"," drill, drill break off and run" and" sleeve" and other accident prevention and disposal technology were described.By the indoor experiment and field practice, the paper had established a plant plastic foam liquid medium in the basic model, and obtained the formula as:vegetable gum content by volume ratio is2.5%～3%, foaming agent twelve benzene sulfonate (ABS) volume fraction ratio of0.2%, degradable polyacrylamide content by volume ratio of0.05%～0.08%, gaseous phase and liquid phase volume ratio control in20:1range. Through the practice of inspection and analysis, the paper thank that its wall protection and leaking stoppage characteristics mainly were: plant plastic foam mud anti-sloughing, network structure, low loss of water leakage, viscoelastic and low density and low leakage plug flow and debris coalescence plugging.(1) Plant gum foam mud preventing collapse characteristics were mainly shown in two aspects:on the one hand, the foam fluid itself had a stronger hydrophobic characteristics, it was easy to be adsorbed on the drilling wall forming the hydrophobic foam wall; on the other hand, the drilling fluid in the polymer with a long chain of bridge structure, the drilling fluid medium formed a dense population space netted structure, and had strong structural viscosity, on the wall surface medium hydration plays an obvious inhibition.(2) Network structure of leakproof effect was mainly manifested as:when drilling to leakage formation period, during the drilling pressure, vegetable gum foam drilling fluid medium into the wall around the leakage crack, and drilling waste slag or cracks in the residues were bonded to each other and quickly gathered to form groups of coalescence state. First of all, it was in a leakage passage to maintain a low shear rate, better reduces the drilling fluid in the channel within the energy flow; secondly, as the mesh structure of stacked superposition, that had been gathered into the foam fluid mesh structure to surface elastic deformation way bonding adsorption later drilling fluid medium three-phase body, better to retard the flow of the drilling fluid impact, further slowing its shear rate, accompanied by a sidewall leakage slit channel had been the foam fluid filled pile net structure, plug, gradually formed a good hydrophobic foam fluid barrier, to weaken or even hinder the drilling fluid leakage effect.(3) Low water loss characteristics mainly as follows: first, vegetable gum drilling fluid structure of medium viscosity than the general low solid drilling fluid was much higher, more conducive to groups of reticular formation, and had compact structure, effectively inhibit the free flow of water, the solid particle fractions increase plant foam drilling fluid flow resistance, effectively reducing the drilling fluid medium water loss; two, vegetable gum drilling fluid medium surface was a mixture of membrane structure, because of the viscosity ratio of free water in drilling fluids of high viscosity, in drilling fluid flow process on the one hand the molecular form a mutual attraction traction, the traction force could inhibit the free flow of water, the other side at the same time in the low hydrostatic fluid column pressure, density and borehole wall under the action of internal pressure in the wellbore formation, a layer of relatively rigid waterproof film layer, well stop the water medium and the wall between the contact, slowing the stratum hydration, played a role in prevention of borehole collapse.(4) Viscoelastic and low density leak-proof characteristics mainly were:in plant gum foam drilling fluid medium, lignin and hemicellulose by hydrogen bonding, ester or ether bond chemical reaction, not only enhanced the drilling fluid medium structural strength, but also maked the drilling fluid medium have certain compressible and expandable, viscoelastic characteristics, effectively slowing the drilling fluid suction pressure and drilling stamping on the sidewall of the scouring action, played a better role in preventing the collapse of.(5) Low speed plug flow and debris coalescence plugging characteristics mainly were:plant plastic foam fluid suspension and adsorption capacity was not dependent on the drilling process itself a higher rate of return, but depended on the plant gum foam fluid formed by the mutual superposition of the reticular structure itself, drilling fluid medium for low-speed slug flow characteristics, effectively weakening the drilling fluid itself against the sidewall of the disturbance and erosion.On the basis of this, the paper designed, optimized and improved the plant gum foam application technology, its inspection and assessment shown those application value and popularization meaning.Finally, based on the field test was found in a restricted technology popularization and application of technical problems, the paper, by the repeated tests and research, proposed solutions, and had obtained the very good application effect.