Yi Hua Dou

Development of the Ring Block Drill Pipe Casing Wear Tester and Experimental Research

In deep wells and ultra-deep wells the complex geological conditions often result in serious casing wear. In order to be able to accurately measure the wear efficiency and friction coefficient required in the process of the prediction of casing wear, a ring-block drill pipe and casing wear tester is specifically designed and produced, the scheme of tester is proposed, and the design of structure, driving device, and the detecting system of the friction and contact forces of tester is completed. Adopting the ring block drill pipe casing wear tester and simulating down hole conditions P110 casing wear experiments are finished. The results show that the ring block drill pipe casing wear tester meets the requirement of down hole casing wear experiment. P110 casing wear efficiency decreased with the increasing of wear time. The friction coefficient between the P110 casing and the drill pipe sample is about 0.25.

Analysis of Interaction between HTHP Completion Packer's Slip and the Casing Wall

The HTHP completion packers slip is a key element in ensuring the reliability of the packer. It plays an important part in supporting and locking the seal bore after anchoring in the casing wall. When the slip in touch with the casing, the interaction force between them occurs, and the supporting function of slip relies mainly on the interaction with the casing. This article analyzes the depth of slip into the casing based on the theory analysis and ANSYS finite element analysis. It approves that the biting depth of the slip increases with the load, and with the increase of tooth number, biting depth is gradually reduced. At last, we get the biting depth of the slip when the packer seated, which is 0.5mm~0.7mm. Besides this, we also analyze the VONMISES stress of the slip and the casing system and find that with the increase of tooth number the tooth stress gradually reduced, and that the slip biting depth and tooth stress gradually increase with the load.

Study of the Erosion-Corrosion Behavior of P110, N80 and VM140 Steel in 3.5wt.%NaCl Solutions with Sand

With the development of hydraulic fracturing technology, the failure of the equipments during production test and completion well becomes more and more severe due to the behaviors of erosion-corrosion. In this paper, the erosion-corrosion behaviors of N80, P110 and VM140 materials were investigated with the jet impingement experimental device. The corrosive rate of these materials by the weight loss method was carried out under different flow velocities and jet angles. It was observed that the weight loss of the three materials is increased by the rising of the impact velocity. The relation of erosion-corrosion weight loss to impact velocity is well described as the equation E=KVn (E is the speed, V is fluid velocity, k and n are the fitting parameters). As a results, the resistance ability for corrosion-erosion under experimental conditions is P110>N80>VM140.

Study on the Large Range Torque Transmitter Quickly Assembled Used for the Calibration of Hydraulic Tongs

For oil field, Square surface connection embedded in our torque transmitter are designed to connect 2 torsion rods instead of flanges, which can shorten the radial dimension of the large range torque transmitter, and realizes the rapid assembly in oil field. It is the chemical composition of elastomer that determines the mechanical properties of the elastomer; the paste process of strain gages will affect the parameters of the torque transmitter, such as linearity, measurement accuracy, hysteresis, repeatability etc.

Collapsing Strength Analysis of Bending Part Casing in Horizontal Wells under Three-Point Bending

According to the mechanical characteristics of bending part casing in horizontal well, established the three-point bending casing mechanical model. By analyzing the stress distribution of casing under three-point bending, considering the effects of shear, extrusion, and bending, using the fourth strength theory and Lame formula, collapsing strength formula of bending part casing in horizontal wells under the three-point bending are derived. Effect of built-up rate on the casing collapsing strength was investigated and evaluated using analytical approach as well as FEM. The results show that built-up rate has a significant impact on casing collapsing strength, and collapsing strength of casing decreases significantly as the increasing of the built-up rate. When built-up rate is large, collapsing strength of thick-walled, large diameter casing decreases faster as the increasing of built-up rate; the casing with bigger wall thickness has bigger collapsing strength under the same borehole curvature and steel grade.

Study of Resistance to Wear of P110 Casing Down-Hole in Water Based Mud

The operation of drilling well leads to casing wear to some degree in cased well. The reduced strength of worn casing threats to the safety of well test and completion. In order to calculate casing wear depth and prevent the casing wear, the wear efficiency and friction coefficient is measured in the different wear time, the contact force and the rotating speed. The wear efficiency increases with the contact force and the rotating speed. And the bigger the rotating speed, the bigger the friction coefficient. The wear efficiency of P110 casing is change from 2 to 8×10-13 1/Pa. The rotating speed has less influence on the wear efficient. So it is reasonable that the wear efficiency model is adopted to calculate the wear degree of P110 casing.

Casing Wear Influence Factors and Range Analysis

In the deep and ultra deep well casing wear is serious. The decrease of strength leads to casing damage, affects the follow-up well test and completion. In order to analyze the influence of the contact force, rotating speed, steel grade and muds on casing wear, determine the optimized level collocation scheme which makes casing wear minimum, optimize drilling parameters and casing programs, reduce casing wear, four factors and three levels orthogonal experiment of casing wear was carried out, and the range analysis of the experiment results is made. The results show that the best match of factors is A1B1C1D3, namely when the contact force is 200 N(A1), rotating speed 60 r/min (B1), steel grade N80(C1), oil-based mud (D3) casing wear is minimal. The influence of muds on casing wear is the largest, the next is casing steel grade, and then rotating speed, the effect of the contact force minimal. The improvement of mud performance is best method to reduce casing wear.

Stress Distribution of Wellbore under Non-Uniform In Situ Stress

The distribution of the non-uniform in situ stress around wellbore will impair the stability of the rock of wellbore wall. Drilling the underbalanced wells and depleted formations, the instability of the wellbore can result in the drilling failure. Mechanics model of the wellbore wall rock is developed. According to the relationship between the stress function and components of stresses, the superposition principle is adopted to develop the formulas of the radial, hoop, and shear stresses of the wellbore wall under the non-uniform in situ stress. The formula of the mud density which do not crash the rock of wellbore wall is derived. The error of the mud density between fitting formula developed in the paper and theoretical method is less than 2.5%. The mud density that ensure the stability of wellbore is determined.

The Mechanics Analysis of the Perforated Casing on Reservoir Sanding Finite Tunneling Section

Perforated casing eyehole stress concentration and sanding and compaction are the main reasons of casing abnormal damage during the exploitation. To understand the impact of reservoir sanding on perforated casing strength, fracture mechanics is applied to analyze the stress concentration of casing caused by perforating, while rock mechanics is applied to analyze the load of perforated casing of reservoir sanding limited bailed section, and on this basis, the impact of reservoir sanding on perforated casing strength is analyzed by the three-dimensional finite element model building. The analysis results show that the finite element solution and the theoretical solution of stresses of the perforated casing of reservoir sanding limited bailed section can be verified with each other. Under the same condition, the theoretical solution is bigger than the finite element solution, this is mainly due to the perforated casing additional bending stress effect is considered in the fracture mechanics theoretical analysis. It is conservative to estimate the perforated casing safety by finite element solution, while the theoretical solution is economical.

Erosion-Corrosion Behavior of Hydraulic Perforating Equipment during Fracturing

Erosion-corrosion behavior in downhole tubulars and oilfield ground gathering transferring system is interesting in optimum design. This work is addressed to investigate erosion-corrosion behavior of hydraulic perforating equipment during fracturing. The typical fracturing fluid of 0.2% hydroxypropyl guar gum solution mixed with quartz grain was selected. The relationship between erosion-corrosion rate and flow displacement, the effect of the flow impact angle on erosion-corrosion rate is performed on a jet impingement experimental apparatus. In the experiment situation, the erosion-corrosion rate reaches highest at the impact angle of 45°. The erosion-corrosion rate increased exponentially with the increase of flow displacement. The surface morphology of specimen suffer from erosion-corrosion is analyzed by scanning electron microscopy (SEM) to characterize the erosion-corrosion damage mechanisms.