A Research On Technology For Increasing Rate Of Penetration In Halahatang Region

With the rapidly developing of our country economic,The requirements of oil source increases with each passing day.It is no time to delay to explorate and develop oil source accelerately. As most of other oilfield, The Tarim oilfield has turned the strategic objective of exploration and development to oil-gas reservoir with complex geology, difficulty exploit and deep reservoir.With the exploration turn to complex and deep oil-gas reservoir, the geological conditions of drilling more and more complexed and the challenge of drilling technology appeared more and more prominently.the problems of low ROP, complex conditions under the well exist in exploration is widespread, lead to the low composite economic results.the aim of exploration in complex and deep reservoir is seriously restricted.The down hole problem happen occasionally in Hlahatang area with deep reservoir and lowe ROP in some interval,then the well drilling cycle lengthened and the well drilling investment accrescented.so it is necessary to adopt a new technology, new method and new tools to improve the ROP.so as to accelerate the exploration and save the cost of exploration in Tarim oilfield Halahatang area. Obviously improving the ROP is significant development to Tarim oilfield.This article is on the basis of research about Speed technology in Halahatang region, and we can draw these conclusions as follows:(1) According to the analysis on the drilling situation in Halahatang, we notice that the average straight section of drilled well is quite deep, which is up to6594.25meters; comparing the relatively penetration rate of different layers, we find drilling speed in tertiary stratum is the fastest, which would begin to decrease in cretaceous stratum and reach the slowest one in Ordovician.(2) The reasons which will typically influence the drilling speed in Halahatang region are geo-factors and engineering-factors.①Geo-factors contain:Jurassic stratum and the following are composed of Glutenite. Breccia and sand shale inter-bed, which will increase the consolidation strength and so as to manifest the features of good hardness and abradibility, where the drillability is range from medium to bad; Meanwhile, the layers are easy to swap blocks so as to make the hole irregular; Ordovician stratum and the above belongs to different pressure systems and there exist to be plenty of vertical fractures and caverns which will increase the probability of large leakage in the process of drilling,②engineering-factors include:sidewall stability is poor and lower borehole is seriously expanding:the drills in the lower stratum are easy to be frayed for its poor adaptability.(3) With the help of data of completed wells in Hahalatang region, the drilled wells could be divided into vertical well, horizontal well and directional well. Most of the drills is16"+91/2"+6" and the main type of casing pipe is103/4"+7",which account for50%of the bore frame. (4) We analysis the drills used in Halahatang region with antitheses and find out: the layer above tertiary stratum owns a lower formation specific energy and a faster drilling speed; the deeper the layer is, the higher the specific energy of the driller is and the faster the drilling speed is.(5) After the analysis of well deviation of46wells in Halahatang, we notice that: the well deviation is controlled well between0to5000meters, and the average hole angle is less than1°,in which the maximum one is within3°,but some of these wells have a occasional large well deviation. When the depth is over6000meters,the well deviation are larger and the average hole angle is within3.96°,and the largest hole angle is17.76°in Ordovician.(6) In Halahatang region,71.7percent of the oil wells use combination drilling technology with "PDC and Direct Screw". We discuss drilling speed analysis between5000to6000meters with or without screw-drill..(7) We do some statistic analysis about drilling mud in Halahatang region and learn that:the well depths of all in Halahatang is bellow6000meters, and the main materials in drilling fluid are polymer, poly-sulfur mud and CP pure cationic; polymer with low-solid, KCL-poly-sulfur mud, amargosite-polymer. The density of drilling mud is range from1.01to1.30g/cm3.This article can remand us some conclusions which are as follows:(1) we can gain the factors which may influence the drilling speed through some statistic analysis about geological conditions, formation characteristic and clay mineral components and through some materials about well history, logging, mud and drills of the drilled wells;(2) we gain the optimum proposal of hole geometry through the analysis on straight hole of the drilled wells;(3) Analyzing the bit repairs, we select the reasonable bit type;(4) We appraise the changing rule of different well diameter and dog leg degree so as to provide some reference on controlling the well-bore quality and enhancing the drilling speed.(5) We try to recommend reasonable mud density to different hole section according to the drilling fluid density analysis curves.(6) All the Achievement in this article are used in well12-3, and the drilling speed of that is11percent faster than well12-1(the well adjacent to12-3),where the improvement is remarkable.