A Research Of Drilling And Completion Technique In Dagang Oilfield Deep Well

For building great oilfield, PetroChina Dagang Oilfield Company (hereinafter referred to as PDOC) speeds up arranging exploratory well steps. PDOC planed to drill several deep exploratory wells in2012.To finish PDOC exploration plan successfully, the author carry out the project as a research of drilling and completion Technique in Dagang Oilfield deep well. After research, drilling and completion technique adapt for dagang oilfield formation comes into being and it will promote whole drilling technical level and service capacity.The project is focus on improving drilling rate on penetration(hereinafter referred to as ROP) in large well bore, increasing ROP in deep explotoray well By using combination drilling technique, boosting ROP through enhancing suit for formation lithology bit, studing downhole problem precaution and solving measures and applying under balanced drilling(hereinafter referred to as UBD) technique on location.The Project is to find drilling and completion mating techniques adapt to dagang oilfield formation by available anvance and mature technique integration application and effective technical measures. The anticipate well construction period will be cut down10percent, rate per month will increase10percent, ROP will be up to5percent and nonproductive time will drop30percent. The deep well will be carried out with safety, quickness and high quality.The project is based on drilling deep well in the dagang oilfield and the contractor is No.1Drilling Engineering Company, BHDC(CNPC Bohai Drilling Engineering Company Limited.).According to the research schedule, the project is devided into four steps. The first step is start-up and document collection. The second step is investigation on location. The third step is optimization proposal and test on location. The fourth is accomplish test and writing report.Summarize drilling deep well experience in2011, then apply bit enhance selection, improving ROP in large hole, promotion speed by MWD compound drilling equipment, accident precaution and UBD drilling techniques to drill deep well in dagang oilfield in2012.Finish the research of promotion ROP in large wellbore. The author analyzed the reasons that it will be very slow when drill large hole size in dagang oilfield deep wild cat well and made further effort research on large size bit selection, hydraulic perameters enhancement, increasement broken rock energy on the well bottom and clean-up capacity. After the research, the ROP is increased.Finish the research of promotion ROP by appliance compound drilling technique. The hole section is drilled by mud motor with high quality PDC and the ROP is increased in the deep well.Finish the research of formation lythology fit bit selection. The mud shale and argillaceous sandstone become high densification under the overburden pressure in the dagang oilfield deep section. Not only the hardness and density increase, but also the mechanic property change from brittle rock under nomal pressure to plastic and brittle rock or plastic rock. By formation drillability research, the author caculated formation drillability extreme value and selected bit type fit for different formation.Finish the research of downhole accident and problem precaution and solving measures. The main reasons cause accident and problem are drilling fluid property mismatching to the formation lithlogy and poor quality mud lead to bad mud cake, over sand and wellbore losing steability. Under this circumstance, maintain the high quality drilling fluid property to satisfy the solid-carrying behavior, lubricating and anticaving demanding and to make sure the steable and clear wellbore.Finish the UBD technique on the location. Total drilled four wells with UBD and the formation is Shahejie. Among the four wells, Three wells reached to the UBD aim ignition successfully during drilling and realized drilling with blow out. One well realized aftereffect ignition and reduced mud density effectively and achieved managed pressure drilling.One bit, the type as P13531JG finished drilling design depth during4912-5173m in the fourth section Haigu101well. The drilling perameters as follows:WOB,30KN RPM,70rpm Flow Rate,22L/s Standpipe Pressure,14Mpa. Footage,261m Actual drilling time,48.5h ROP,5.38m/h. Realized to finish the fourth section with only one bit and reduce the tripping time. The bit, type as M1655SS achieved good effection during section2904m to3829m in the well Bin27. The ROP reached to11.42m/h and increased41.6percent contrast with Well Bin85.By the research of accident and problem precaution, the rate of accident and problem reduce56percent contrast with2011.By the research of increasing ROP in the large hole size, the average ROP of the Φ444.5mm wellbore improved60.77percent and the Φ311.1mm wellbore up-to30.27percent in the four sections well and the Φ311.1mm wellbore increased18.56percent in the three sections well.Putting assemble technique of the project research into practice, on the condition of average depth adds up6.09percent in the eleven wells, the average construction cycle reduced15.24percent, the average ROP increased28.59percent, the average footage per month increased22.85percent and the project got satisfied anticipate effection.By optimizing well profile, reducing footage in the large hole, modifying drilling perameter, increasing breaking rock energy in the bottom, improving hydraulic perameter and raising borehole purified capacity, the ROP of the large holesize increased substantially.Applicance compound drilling technique to increase ROP. Started from oprientation, The BHA was run in the hole (RIH) changed to mud motor with MWD and using slipping and steering technique in the∮311. lmm borehole. This proposal increased ROP. For the vertical hole, we used directional mud motor to increased ROP and controlled well trajectory.Focus on the poor drillability in the dagang oilfield deep well, we optimized bit type and got satisfied qualification and increased ROP.By the research of the drilling and completion in the dagang oilfield deep well, we summarized and analysed document of drilling deep well experience in recent, we made research on improving ROP in the large size hole, application compound drilling technique to increase ROP in the deeo well, enhancing formation lithlogy fit bit to increase ROP, downhole accident and problem precaution and sovling technique and UBD drilling techniques to drill deep well in dagang oilfield in2012. From the project, we got some inclusions as follows.From summarized finished well document in the2011deep well, we got the reason that restrict the drilling and completion cycles and ROP. By optimizing well profile, reducing footage in the large hole, modifying drilling perameter, increasing breaking rock energy in the bottom, improving hydraulic perameter and raising borehole purified capacity,the ROP of the large holesize increased substantially.By used compound drilling technique and spread high quality PDC bit, the wells construction cycle was reduced and ROP was increased.Focus on the low ROP in the dagang oilfield deep well, we analyzed rock drillability and optimized bit selection in the different formation and drawed rock drillability extreme value chart, then made optimized bit type in the formation of minghuazheng, guantou, dongying and shahejie formation.By application UBD(MPD)technique in the deep explotory well, we protected reservoir effectively and increased ROP.By the applicance the assemble technique to the lication, the average construction cycle reduced15.24percent, the average ROP increased28.59percent and the footage per month added up22.85percent in the eleven wells under the condition of average depth deepen6.09percent. The project got anticipated aim.