A kind of lower teletype command coding/decoding method of rotary steerable drilling system
Technical field
The present invention relates to for oil exploration and development fields, relate in particular to a kind ofly when passing under surface instruction, downhole system is to the reception of surface instruction and coding/decoding method.
Background technology
In petroleum drilling operation, can realize the rotary steerable drilling system of drilling process closed-loop control is applied in petroleum exploration and development operation gradually.At present, in rotary steerable drilling field, most of key technology all rests in Shou Zhong, domestic corporation of external Ji Jia oil and gas development service company and is in the early stage of development in this field.Along with the fast development of Chinese national economy, increasingly urgent to the exploration and development demand of petroleum resources, more and more higher to the requirement of efficient oil drilling system.Therefore, develop own ripe rotary steerable drilling system, become the vital task of domestic petroleum drilling well industry.
With respect to oil drilling system in the past, a key character of rotary steerable drilling system is exactly the closed-loop control that has realized drilling process, both in drilling process, downhole system is without stop boring in the situation that, can receive the surface instruction transmitting by mud and adjust the running status of drilling tool, wherein a crucial step is exactly that downhole system is to the accurate reception of lower teletype command and resolve.
Existing decoding method, such as referenced patent number: ZL201210113132, generally by control impuls valve, according to the sequential of appointment, open or close, in shaft bottom, produce the transmission that four mud pressure negative pulses complete teletype command under a rotary steering, two command areas and a check field are set in four mud pressure negative pulses, pulse interval permutation and combination in two command areas is got up to characterize the lower teletype command sending, the pulse interval of check field is used as to teletype command under verification; Corresponding with coding method, coding/decoding method detects the trailing edge of four the mud pressure negative pulses in shaft bottom by shaft bottom mud device for pressure measurement, obtain the time parameter corresponding with command area and check field in actual measurement pulse, then by calculating, parse the lower teletype command that shaft bottom receives, and its correctness of verification.The method instruction decoding method more complicated, and because subsurface environment is very complicated, there is the disturbing factors such as various high-intensity vibrations, impact, electromagnetic interference, downhole system can be subject to impact in various degree to the reception of the mud pulse signal passing down and correct identification, even can cause under information and pass failure.
Therefore, how to receive and the breath of correctly delivering a letter under identification is the essential problem solving in rotary steerable drilling system development process.
Summary of the invention
The object of this invention be to provide a kind of can be to the underground processing method that breath accurately receives and identifies of delivering a letter, solved the breath of time delivering a letter because of decay, disturb the reception and the high difficult problem of identification error rate that cause.
Technical scheme of the present invention is:
A lower teletype command coding/decoding method, the steps include:
1) rotary steering system is converted to lower teletype command by instruction converting unit the mud flow rate information of setting pulsewidth, sends to the downhole control system of rotary steering system;
2) downhole control system Real-time Collection mud flow rate information, and the data on flows collecting within the scope of certain hour is carried out to filtering processing, if the data peaks after processing reaches setting value H, is determined with command information and passes under starting, and carries out step 3); Otherwise do not have to pass under command information;
3) downhole control system Real-time Collection mud flow rate information carry out matched filtering processing, the pulse position information that obtains down passing;
4) downhole control system calculates the Grad of each pulse according to the pulse position information of determining, if Signal gradient changes, surpasses setting value h1 and for just, judges and occur rising edge of a pulse; If Signal gradient changes, surpass setting value h2 and for negative, judge and occur pulse trailing edge;
5) command information that downhole control system obtains down passing according to the pulse signal information of determining.
Further, described pulse signal information comprises position and the pulse width of pulse signal.
Further, when being determined with command information and passing under starting, described downhole control system sends instruction immediately to the uploading tools of downhole control system, stops the work of this uploading tools.
Further, described setting value H is greater than setting value h1, setting value h2.
Further, described setting value h1>h2.
Compared with prior art, good effect of the present invention is:
Complex environment due to down-hole; often can produce high-intensity vibration, impact; produce either large or small pulse; the time that these interfering signals produce and size are difficult to control; and then the transmission severe jamming to mud-pulse information; the present invention utilizes matched filtering algorithm, by passing down the suitable adjustment of pulse width, improve under the deliver a letter accuracy rate of breath identification.By the rate of change along near Signal gradient to mud-pulse rising (decline), determine mud-pulse position, thereby the command information that obtains down passing according to the pulse information decoding has improved the accuracy rate of decoding greatly.
For the ease of downhole system, accurately identify will have under information and pass, the present invention spreads while beginning under information, first produce a stronger pulse information, peak value H is greater than the peak value of information pulse, so that downhole system is accurately judged, by having under information, passes and preparation for acquiring, identification and decoding.
Consider that pulse is in actual propagation process, the general meeting of trailing edge is lower than the height of rising edge, so the present invention is set as h1<h2 by the detected value in pulse detection process.
Accompanying drawing explanation
Accompanying drawing is method flow diagram of the present invention.
The specific embodiment
Algorithm structure of the present invention is divided into two parts, utilizes matched filtering algorithm pulse signals to process, and passes having judged whether under information; After defining and passing under information, utilize the change of gradient information of mud-pulse, determine rising edge and the trailing edge of mud-pulse, determine the position of mud-pulse, thus realize under the deliver a letter accurate reception of breath.Algorithm flow chart as shown in drawings.
One. under information, pass evaluation algorithm
Rotary steering system is in drilling process, and aboveground control system is converted to mud flow rate information by instruction converting unit by lower teletype command and sends to downhole control system; Downhole control system constantly gathers mud flow rate information, and utilizes matched filtering algorithm to process to the data on flows collecting within the scope of certain hour.Data after matched filtering are judged, if the data peaks after processing reaches some setting value H, think and have information to pass under starting, otherwise think do not have to pass under information.
Two. under information, pass pulse recognition algorithm
Owing to judging to have under information, pass, downhole control system can send instruction immediately, stop down-hole uploading tools work (with reduce under the deliver a letter interference of breath), and pass pulse information under gathering.Pulse information to gathering, calculates its Grad, if Signal gradient changes, surpasses a certain setting value h1 and for just, thinks and occur rising edge of a pulse; If Signal gradient changes, surpass a certain setting value h2 and for negative, think to occur pulse trailing edge; Last downhole control system obtains according to decoded pulse signal the command information that underground passes.