Research On The Igneous Rock Crushing Mechanism And Efficiency In Deep Reservoir Of Songliao Basin

Deep igneous rocks are widely distributed in the Songliao Basin, including a largesegment of intermediate-acid volcanic eruptive rock, rhyolite, glutenite, tuff, basalt, brecciaand andesite, and so on. These igneous rock formations has many characteristics such as highhardness, strong abrasive, high drillability, strong longitudinal and transverse heterogeneity,which bring drilling operation a lot of difficult, resulting in existing drill bit with pooradaptability, rock-breaking efficiency not high, drill bit accidents frequent, single bit footagesmall, and service life short. For example, as nearly two years, in northern Songliao BasinXujiaweizi Gas-field the gas-wells drilled are affected, with the average depth of3725m, theaverage drilling cycle of120.1d, the average thickness of Yingcheng Group and belowformations of400~700m, the average single bit footage only56.21m, needing cone drill9~13, the trip ROP only0.92m/h, severely restricting and impacting on the exploration anddevelopment of deep oil and gas.In response to the above problem, this paper carry out a thorough study on the igneousrock crushing mechanism in deep reservoir, the main work and results are as follows:(1) It is carried out to study the basic physical and mechanical properties of differentlithologic igneous rock, which is with different logging response characteristics. In this paper,by using well logging data, log data and core data, and applying the theory of neural network,a method to identify the lithology of igneous rock is established. Through the indoorexperiment, the density characteristics of igneous rock, thermodynamic properties, Biotparameters and full stress-strain curve are analyzed, and many deformation parameters andstrength parameters such as the compressive strength, elastic modulus, Poisson's ratio,cohesion, internal friction angle and tensile strength are calculated. Combined with thelaboratory test and well logging data, the log interpretation model of physical and mechanicalparameters of igneous rock is established, and the rock mechanics parameters profile of somewells such as Xushen44in northern Songliao Basin is calculated.(2) The anti-drilling characteristics of different lithologic igneous rock are studied. Theanti-drilling parameters of the deep igneous rock in Songliao Basin are tested, including thehardness, plasticity coefficient, drillability level values and abrasive property. The predictionmodel of anti-drilling parameters based on log interpretation is set up to calculate theanti-drilling characteristics profile of Xushen41,44and other wells. Using fuzzy clusteringmethod, according to the drillability an approach of formation layered is built. For theprediction problem before drilling, an prediction method of anti-drilling characteristics uponthe finite element interpolation method is established, and it has been applied in YingchengGroup of Xingcheng Gas-field in northern Songliao Basin.(3) The research on regional ground stress characteristics is conducted. Coring theigneous rock of Xingcheng Gas-field in Songliao Basin and applying the paleomagnetic experiment and differential strain experiment, the ground stress size and direction of thesingle well point is tested. Combined with the ground stress log interpretation information andregional geological features, and using the ground stress field inversion method ofmulti-source information integration and fusion, present three-dimensional ground stress fieldof Yingcheng Group in Xingcheng Gas-field of Songliao Basin is calculated.(4) The bit suitability of igneous rock formation is studied. This paper analysesstatistically the bit usage of deep igneous rock formation in northern Songliao Basin, andstandardized processing, forming the database of drill bit use. Then through comparing thedrilling rate, drilling time, footage and other technical indicators, the suitability of the existingbit and formation is analyzed. Applying the improved main component algorithm, the existingbit is analyzed and optimized. And according to the failure situation and reason of the bit, thecorresponding improvement program is put forward.(5) The contact coupling mechanism of igneous rock formation and bit teeth is analyzed.According to the elasticity mechanics and contact mechanics, in the process of the teeth withdifferent tooth profile contacting formation rock, the elastic stress state, invasion process androck crushing mechanism are analyzed, and the generating conditions and discriminant modelunder different stage including elastic-plastic deformation, formation of compaction andvolumetric crushing are established. Combined with the simulation experiment of the singletooth crushing rock, the influence factor and law of rock fragmentation efficiency areobtained.(6) Based on the coupling model of bit teeth and formation, the rock fragmentationefficiency and wear evaluation theory of the impregnated diamond bit are built, and the designmethod of some parameters of diamond such as particle size, concentration and tire bodystrength is formed. According to the formation characteristics of igneous rock, a kind ofcutting-abrasive drill is designed and developed, which has been applied in field of Gushen3well and Dashen15well, achieving good accelerated effect.The above research results further reveal the basic physical and mechanical properties ofthe deep igneous rock in Songliao Basin, anti-drilling characteristics, ground stresscharacteristics and basic crushing rule. It provides a technical support for the effectivedevelopment of igneous gas reservoirs, which is conducive to increasing drilling speed andreducing operating costs.