Tarim Kuqa tight sandstone reservoir is overlaid with extreme thick conglomerate, which has high compressive strength, strong heterogeneity and poor drill ability, resulting in low drilling ROP and less bit drilling footage. Through research study and analysis of PDC bit failure and wear modes, this paper described the development of an innovative non-planar PDC bit through cutting mechanism study and lab testing verification. When drilling through the strong homogeneity formation, it will still be surface contact between the non-planar cutter and the rock and therefore the rock-breaking mechanism is still the conventional shearing fracturing; When drilling through the heterogeneity formation, the convex ridges will generate the linear contact with the hard rock and the mechanical stress will be accumulated at the conglomerate surface to initially create the cracking and then break the rock with composite cutting mechanism of shearing and crushing to improve the rock breaking efficiency. Experimental results also showed that the non-planar cutter delivers several folds of impact resistance improvement over conventional cutter. The bit was successfully field tested in ultra-thick conglomerate layer in the Kuqa foreland thrust belt of the Tarim basin. The field test tripled bit footage and doubled ROP comparing to same intervals and formation in offset wells. It demonstrated the broader prospect of the non-planar PDC technology in conglomerate and highly heterogeneous applications.
Along with the development of ocean oil and gas exploration to the deep-water, the down-hole temperature is more and more higher with the drilling depth increasing. The down-hole hydraulic dynamic drilling tool does not adapt to the needs of the offshore deep-water drilling. Therefore, development of high resistant temperature, excellent oriented performance down-hole motor is imminent. The author designed a new type rigid blade down-hole power drilling tool, its slipping blade belongs to the rigid blade, which has the advantages of large output torque and high reliability compared with the domestic and foreign down-hole dynamic drilling tool. This paper mainly carried on the numerical simulation calculation to the 178mm down-hole motor. The calculation model was established based on characteristics of the new type blade dynamic drilling tool. The fluent software was used to calculate different pressure and velocity distribution at the different flow rate and different speed of rotator. The calculation results show that when the drilling fluid flow rate from 30 to 35L/s and the rotator speed is 180rpm, the dynamic drilling tool can achieve the best efficiency, and the abrasion of the motor blade and other parts is minimum. The results can provide the basis for the optimization of the structure parameters and working parameters of the new type down-hole dynamic drilling tool.
Abstract Upward trends in oil prices and the proliferation of new technology enable operators to capitalize on new opportunities. This trend is not limited to previously undeveloped fields or by lithology. Operators are also able to gain higher recovery from old fields where production has declined over time, making new opportunities for matching technology to economies of scale for such marginal projects. This paper outlines the recompletion of an old field using radial jet drilling, RJD. The reservoir in K-block, Tarim oilfield of China is a siltstone formation with low permeability and was damaged by the mud. The combination of low permeability, low productivity from traditional vertical completions in a thin net pay, and lack of low cost techniques to improve well productivity caused the production to dwindle. In 2012, the operator implemented a program of radial jet drilling to enhance field production. Radial jet drilling is a low-cost, environmentally-friendly method to drill numerous small diameter horizontal laterals from a vertical or near-vertical wellbore. It works in both new and old wells that already have a production history. The present paper outlines the completion and production history of the field, summarizes the workover effort and the production data before and after the workovers. The results show that nearly a 300% production increase was obtained. It can be clearly seen that radial jet drilling can be a viable alternative to improve productivity of shallow reservoirs that still have significant oil in place that can’t be produced with the existing conventional completions.
The unusually ultra-deep and ultra-high-pressure gas reservoirs in the Keshen 8 Block on the Kelasu structural belt of the Tarim Basin are also featured by high temperature, well-developed fault fissures, huge thickness, tight matrix, complex oil–water distribution, etc., which brings about great difficulties to reserves evaluation and further development. In view of this, an overall study was made on the fine description of reservoir fractures and their seepage mechanism, technical problems were being tackled on seismic data processing and interpretation of complex and high & steep structural zones, optimal development design, safe & rapid drilling and completion wells, reservoir stimulation, dynamic monitoring, etc. to promote the development level of such ultra-deep tight gas reservoirs, and 22 complete sets of specific techniques were formulated in the fields of high-efficiency well spacing, safe and fast drilling, recovery enhancement by well completion transformation, efficient development of optimization design, and so on. Through the technical progress and innovative management of integrated exploration & development, reserves evaluation and productivity construction have been completed on the Keshen 8 Block in the last three years of the 12th Five-Year Plan period (2011–2015), as a result, rapid and high-efficiency productivity construction is realized, and a new area is explored in the development of ultra-deep and ultra-high-pressure fractured tight sand gas reservoirs. This study is of great reference to the development of similar gas reservoirs at home and abroad.
Abstract The implementation of drilling technique for multiple lithology interbeds and high-pressure anhydrite-salt in the complex Mountain Front area has been completed. The plastic creep of the anhydrite-salt layers, the losses of the low-pressure sandstone, the overflow of the high-pressure salt-water, the narrow mud density window and frequent pipe-stuck occurrence are significant issues, which trigger significant engineering challenges downhole. This study presents the application of the reaming-while-drilling (RWD) technology which has led to minimize the downhole non-productive time (NPT) and achieve successful results. The RWD technique was applied in the composite anhydrite-salt formation of the Kumugeliemu group. Through optimized combination of the RWD tools, bits, reaming blades, and the mechanical analysis the drill string with shock-absorbing design and hydraulics optimization to guarantee the bit and the reamer blades have the proper pressure drop, hydraulic horsepower and flow-field distribution, the RWD was used with the vertical seeking tool drilling technology, resulting in minimum vibration and/or stick-slip, and achieving the expected rate of penetration (ROP) as well as target inclination. It improved the operation efficiency significantly while avoiding the downhole complexities at the same time. Since the geological structure of the offset well Keshen X (no RWD) is similar to Keshen XX (RWD technology was applied), a comparison between the two wells was performed. The reaming meterage in the composite anhydrite-salt layers in Keshen XX was 791 m, spending 15 days, average ROP is 3.73 m/hr. There was no overflew or loss during the drilling. It was smooth, no pipe sticking when checking the reaming effect during the wiper trip and the tripping out. On the other hand, Keshen X spent 29 days with average ROP of 1.35 m/hr to drill the 449 m composite anhydrite-salt rock. Moreover, it was difficult to trip in and trip out during the drilling, and the pipe sticking happened frequently, back-reaming frequently as well. There were losses during both the drilling and the casing running. Due to the unsmooth wellbore, this well increased additional 3 runs of reaming after drilling operation and 4 clean-out runs. 13 days later after the reaming operation, the anhydrite-salt rock creep was checked and found that the hole was still smooth, no pipe sticking existing. Hence, RWD technology has accomplished both goals of preventing the downhole complexities and speeding up drilling. The novel RWD technology can be well illustrated by presenting all the details of its application in salt-base formations.
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