CNPC's New Progress in Well Cementing Techniques

Well cementing is an important step in petroleum engineering territory. Through many years study and research, China Nation Petroleum Corporation(abbreviated as CNPC) has made many good progresses in cementing process, and a series of cementing materials, cementing tools, and associated cementing techniques to them have been developed. Over the recent years, there have been significant improvements in application of single slurry system to super deep well, horizontal well, large displacement well and wells with large temperature span between cementing top and well bottom. Favorable results have been gained in field application of super high density cement slurry system and super low density cement slurry system. Application of conventional cementing tools and accessories has been the matured techniques, and breakthroughs have been made in liner hanger and swellable material.

Influence of Characteristics of Alumina-silicate Raw Materials on the Formation Process of Clinker

The traditional alumina-silicate raw materials, for example, clays, in the precalcining technique of cement production, have been replaced by low grade and high silica content sandstones, shales, and industrial waste residues, including fly ashes, slag, and others. The results are the change of compositions and characteristics of raw materials applied and a great effect on cement calcination process and clinker formation. In this work, the cement clinker formation process of different alumina-silicate raw materials to replace clay raw material was studied by chemical analysis, X-ray diffraction, differential thermal analysis, and high temperature microscope based on the characteristics of the alumina-silicate raw materials. The formation heat of the clinker was determined by the acid dissolution method. Influence of different alumina-silicate raw materials on the clinker burnability and formation process was studied. The results show that the changing of alumina- silicate raw materials, especially using industrial waste residues, can reduce the formation temperature of high temperature liquid phases, improve the burnability of raw materials, reduce the formation temperature and formation heat of clinker. And this study also observed the formation temperature and transformation of high temperature liquid phases in the heating process of raw materials by high temperature microscope.

Loose Sand Particles Cemented by Chem/Bio-BaHPO_4 Powder

Bacillus subtilis was selected as the suitable microorganism,which could produce alkaline phosphatase and constantly hydrolyzed phosphate monoester in the mixture solution of bacteria with substrate,and then the PO4^3-was obtained.Bio-phosphate cement was prepared by alkaline earth element（Ba）ions reacting with PO4^3-in the mixture solution.Structure,size and thermal properties of the bio-phosphate cement were characterized by energy dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and particle size analysis.The average crystallite sizes of chem-BaHPO4 and bio-BaHPO4corresponded to 11.99 and 24.13μm,respectively.Chem-BaHPO4 and bio-BaHPO4 were then adopted to bind loose sand particles.The results indicated that loose sand particles can be well cemented by the bio-BaHPO4powder into a bio-sandstone with a certain mechanical properties,and the average compressive strength of the bio-sandstones can be up to 0.83 MPa when the curing time was 14 d.Along with the method in future studies,there will be multiple new opportunities for engineering applications,for instance,the treatment of sandy soil foundation,remediation of heavy metals in contaminated soil,and so on.